PostgreSQL 7.3.2 Administrator’s
Guide
The PostgreSQL Global Development Group
PostgreSQL 7.3.2 Administrator’s Guide
by The PostgreSQL Global Development Group
Copyright © 1996-2002 by The PostgreSQL Global Development Group
Legal Notice
PostgreSQL is Copyright © 1996-2002 by the PostgreSQL Global Development Group and is distributed under the terms of the license of the
University of California below.
Postgres95 is Copyright © 1994-5 by the Regents of the University of California.
Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a written agreement
is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in all copies.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCI-
DENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IM-
PLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HERE-
UNDER IS ON AN “AS-IS” BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
Table of Contents
Preface .........................................................................................................................................................i
1. What is PostgreSQL?......................................................................................................................i
2. A Short History of PostgreSQL ......................................................................................................i
2.1. The Berkeley POSTGRES Project ................................................................................... ii
2.2. Postgres95......................................................................................................................... ii
2.3. PostgreSQL...................................................................................................................... iii
3. What’s In This Book .....................................................................................................................iv
4. Overview of Documentation Resources........................................................................................iv
5. Terminology and Notation .............................................................................................................v
6. Bug Reporting Guidelines.............................................................................................................vi
6.1. Identifying Bugs...............................................................................................................vi
6.2. What to report................................................................................................................. vii
6.3. Where to report bugs ..................................................................................................... viii
1. Installation Instructions........................................................................................................................1
1.1. Short Version...............................................................................................................................1
1.2. Requirements ..............................................................................................................................1
1.3. Getting The Source .....................................................................................................................3
1.4. If You Are Upgrading .................................................................................................................4
1.5. Installation Procedure .................................................................................................................5
1.6. Post-Installation Setup ..............................................................................................................10
1.6.1. Shared Libraries............................................................................................................11
1.6.2. Environment Variables .................................................................................................11
1.7. Supported Platforms..................................................................................................................12
2. Installation on Windows......................................................................................................................18
3. Server Run-time Environment ...........................................................................................................19
3.1. The PostgreSQL User Account.................................................................................................19
3.2. Creating a Database Cluster......................................................................................................19
3.3. Starting the Database Server.....................................................................................................20
3.3.1. Server Start-up Failures................................................................................................21
3.3.2. Client Connection Problems.........................................................................................22
3.4. Run-time Configuration ............................................................................................................23
3.4.1. pg_settings....................................................................................................................24
3.4.2. Planner and Optimizer Tuning......................................................................................24
3.4.3. Logging and Debugging...............................................................................................26
3.4.4. General Operation ........................................................................................................29
3.4.5. WAL .............................................................................................................................36
3.4.6. Short Options................................................................................................................37
3.5. Managing Kernel Resources .....................................................................................................38
3.5.1. Shared Memory and Semaphores.................................................................................38
3.5.2. Resource Limits............................................................................................................42
3.6. Shutting Down the Server.........................................................................................................43
3.7. Secure TCP/IP Connections with SSL......................................................................................44
3.8. Secure TCP/IP Connections with SSH Tunnels........................................................................45
iii
4. Database Users and Privileges............................................................................................................47
4.1. Database Users..........................................................................................................................47
4.2. User Attributes..........................................................................................................................47
4.3. Groups.......................................................................................................................................48
4.4. Privileges...................................................................................................................................48
4.5. Functions and Triggers..............................................................................................................49
5. Managing Databases............................................................................................................................50
5.1. Overview...................................................................................................................................50
5.2. Creating a Database ..................................................................................................................50
5.3. Template Databases...................................................................................................................51
5.4. Database Configuration.............................................................................................................52
5.5. Alternative Locations................................................................................................................53
5.6. Destroying a Database...............................................................................................................54
6. Client Authentication...........................................................................................................................55
6.1. The pg_hba.conf file..............................................................................................................55
6.2. Authentication methods ............................................................................................................59
6.2.1. Trust authentication......................................................................................................59
6.2.2. Password authentication...............................................................................................60
6.2.3. Kerberos authentication................................................................................................60
6.2.4. Ident-based authentication............................................................................................61
6.2.4.1. Ident Authentication over TCP/IP....................................................................61
6.2.4.2. Ident Authentication over Local Sockets.........................................................62
6.2.4.3. Ident Maps .......................................................................................................62
6.2.5. PAM Authentication.....................................................................................................63
6.3. Authentication problems...........................................................................................................63
7. Localization..........................................................................................................................................65
7.1. Locale Support..........................................................................................................................65
7.1.1. Overview ......................................................................................................................65
7.1.2. Benefits.........................................................................................................................66
7.1.3. Problems.......................................................................................................................67
7.2. Multibyte Support .....................................................................................................................68
7.2.1. Supported character set encodings ...............................................................................68
7.2.2. Setting the Encoding.....................................................................................................69
7.2.3. Automatic encoding conversion between server and client..........................................70
7.2.4. What happens if the translation is not possible? ..........................................................72
7.2.5. References ....................................................................................................................72
7.2.6. History..........................................................................................................................72
7.2.7. WIN1250 on Windows/ODBC.....................................................................................74
7.3. Single-byte character set recoding............................................................................................75
8. Routine Database Maintenance Tasks...............................................................................................77
8.1. General Discussion ...................................................................................................................77
8.2. Routine Vacuuming...................................................................................................................77
8.2.1. Recovering disk space ..................................................................................................77
8.2.2. Updating planner statistics ...........................................................................................78
8.2.3. Preventing transaction ID wraparound failures............................................................79
8.3. Routine Reindexing...................................................................................................................80
iv
8.4. Log File Maintenance ...............................................................................................................81
9. Backup and Restore.............................................................................................................................82
9.1. SQL Dump................................................................................................................................82
9.1.1. Restoring the dump.......................................................................................................82
9.1.2. Using pg_dumpall......................................................................................................83
9.1.3. Large Databases............................................................................................................83
9.1.4. Caveats..........................................................................................................................84
9.2. File system level backup...........................................................................................................85
9.3. Migration between releases.......................................................................................................85
10. Monitoring Database Activity ..........................................................................................................87
10.1. Standard Unix Tools................................................................................................................87
10.2. Statistics Collector ..................................................................................................................88
10.2.1. Statistics Collection Configuration.............................................................................88
10.2.2. Viewing Collected Statistics.......................................................................................88
10.3. Viewing Locks ........................................................................................................................92
11. Monitoring Disk Usage......................................................................................................................95
11.1. Determining Disk Usage.........................................................................................................95
11.2. Disk Full Failure .....................................................................................................................96
12. Write-Ahead Logging (WAL)...........................................................................................................97
12.1. General Description ................................................................................................................97
12.1.1. Immediate Benefits of WAL.......................................................................................97
12.1.2. Future Benefits............................................................................................................97
12.2. Implementation .......................................................................................................................98
12.2.1. Database Recovery with WAL ...................................................................................98
12.3. WAL Configuration.................................................................................................................99
13. Regression Tests...............................................................................................................................101
13.1. Introduction...........................................................................................................................101
13.2. Running the Tests..................................................................................................................101
13.3. Test Evaluation......................................................................................................................102
13.3.1. Error message differences ........................................................................................102
13.3.2. Locale differences.....................................................................................................103
13.3.3. Date and time differences.........................................................................................103
13.3.4. Floating-point differences.........................................................................................103
13.3.5. Polygon differences..................................................................................................104
13.3.6. Row ordering differences .........................................................................................104
13.3.7. The “random” test.....................................................................................................104
13.4. Platform-specific comparison files........................................................................................105
A. Release Notes.....................................................................................................................................106
A.1. Release 7.3.2 ..........................................................................................................................106
A.1.1. Migration to version 7.3.2 .........................................................................................106
A.1.2. Changes .....................................................................................................................106
A.2. Release 7.3.1 ..........................................................................................................................107
A.2.1. Migration to version 7.3.1 .........................................................................................107
A.2.2. Changes .....................................................................................................................107
A.3. Release 7.3 .............................................................................................................................107
A.3.1. Overview....................................................................................................................108
v
A.3.2. Migration to version 7.3 ............................................................................................109
A.3.3. Changes .....................................................................................................................109
A.3.3.1. Server Operation ...........................................................................................109
A.3.3.2. Performance ..................................................................................................110
A.3.3.3. Privileges.......................................................................................................110
A.3.3.4. Server Configuration.....................................................................................110
A.3.3.5. Queries..........................................................................................................111
A.3.3.6. Object Manipulation .....................................................................................112
A.3.3.7. Utility Commands.........................................................................................112
A.3.3.8. Data Types and Functions.............................................................................113
A.3.3.9. Internationalization .......................................................................................115
A.3.3.10. Server-side Languages................................................................................115
A.3.3.11. Psql..............................................................................................................115
A.3.3.12. Libpq...........................................................................................................116
A.3.3.13. JDBC...........................................................................................................116
A.3.3.14. Miscellaneous Interfaces.............................................................................116
A.3.3.15. Source Code................................................................................................117
A.3.3.16. Contrib ........................................................................................................118
A.4. Release 7.2.4 ..........................................................................................................................119
A.4.1. Migration to version 7.2.4 .........................................................................................119
A.4.2. Changes .....................................................................................................................119
A.5. Release 7.2.3 ..........................................................................................................................119
A.5.1. Migration to version 7.2.3 .........................................................................................119
A.5.2. Changes .....................................................................................................................120
A.6. Release 7.2.2 ..........................................................................................................................120
A.6.1. Migration to version 7.2.2 .........................................................................................120
A.6.2. Changes .....................................................................................................................120
A.7. Release 7.2.1 ..........................................................................................................................121
A.7.1. Migration to version 7.2.1 .........................................................................................121
A.7.2. Changes .....................................................................................................................121
A.8. Release 7.2 .............................................................................................................................121
A.8.1. Overview....................................................................................................................121
A.8.2. Migration to version 7.2 ............................................................................................122
A.8.3. Changes .....................................................................................................................123
A.8.3.1. Server Operation ...........................................................................................123
A.8.3.2. Performance ..................................................................................................123
A.8.3.3. Privileges.......................................................................................................124
A.8.3.4. Client Authentication....................................................................................124
A.8.3.5. Server Configuration.....................................................................................124
A.8.3.6. Queries..........................................................................................................124
A.8.3.7. Schema Manipulation ...................................................................................124
A.8.3.8. Utility Commands.........................................................................................125
A.8.3.9. Data Types and Functions.............................................................................125
A.8.3.10. Internationalization .....................................................................................126
A.8.3.11. PL/pgSQL ...................................................................................................126
A.8.3.12. PL/Perl ........................................................................................................127
A.8.3.13. PL/Tcl..........................................................................................................127
A.8.3.14. PL/Python ...................................................................................................127
vi
A.8.3.15. Psql..............................................................................................................127
A.8.3.16. Libpq...........................................................................................................127
A.8.3.17. JDBC...........................................................................................................127
A.8.3.18. ODBC..........................................................................................................128
A.8.3.19. ECPG ..........................................................................................................128
A.8.3.20. Misc. Interfaces...........................................................................................129
A.8.3.21. Build and Install..........................................................................................129
A.8.3.22. Source Code................................................................................................129
A.8.3.23. Contrib ........................................................................................................130
A.9. Release 7.1.3 ..........................................................................................................................130
A.9.1. Migration to version 7.1.3 .........................................................................................130
A.9.2. Changes .....................................................................................................................130
A.10. Release 7.1.2 ........................................................................................................................131
A.10.1. Migration to version 7.1.2 .......................................................................................131
A.10.2. Changes ...................................................................................................................131
A.11. Release 7.1.1 ........................................................................................................................131
A.11.1. Migration to version 7.1.1 .......................................................................................131
A.11.2. Changes ...................................................................................................................131
A.12. Release 7.1 ...........................................................................................................................132
A.12.1. Migration to version 7.1 ..........................................................................................132
A.12.2. Changes ...................................................................................................................133
A.13. Release 7.0.3 ........................................................................................................................136
A.13.1. Migration to version 7.0.3 .......................................................................................136
A.13.2. Changes ...................................................................................................................136
A.14. Release 7.0.2 ........................................................................................................................137
A.14.1. Migration to version 7.0.2 .......................................................................................138
A.14.2. Changes ...................................................................................................................138
A.15. Release 7.0.1 ........................................................................................................................138
A.15.1. Migration to version 7.0.1 .......................................................................................138
A.15.2. Changes ...................................................................................................................138
A.16. Release 7.0 ...........................................................................................................................139
A.16.1. Migration to version 7.0 ..........................................................................................139
A.16.2. Changes ...................................................................................................................140
A.17. Release 6.5.3 ........................................................................................................................146
A.17.1. Migration to version 6.5.3 .......................................................................................146
A.17.2. Changes ...................................................................................................................146
A.18. Release 6.5.2 ........................................................................................................................147
A.18.1. Migration to version 6.5.2 .......................................................................................147
A.18.2. Changes ...................................................................................................................147
A.19. Release 6.5.1 ........................................................................................................................147
A.19.1. Migration to version 6.5.1 .......................................................................................148
A.19.2. Changes ...................................................................................................................148
A.20. Release 6.5 ...........................................................................................................................148
A.20.1. Migration to version 6.5 ..........................................................................................149
A.20.1.1. Multiversion Concurrency Control .............................................................150
A.20.2. Changes ...................................................................................................................150
A.21. Release 6.4.2 ........................................................................................................................153
A.21.1. Migration to version 6.4.2 .......................................................................................154
vii
A.21.2. Changes ...................................................................................................................154
A.22. Release 6.4.1 ........................................................................................................................154
A.22.1. Migration to version 6.4.1 .......................................................................................154
A.22.2. Changes ...................................................................................................................154
A.23. Release 6.4 ...........................................................................................................................155
A.23.1. Migration to version 6.4 ..........................................................................................156
A.23.2. Changes ...................................................................................................................156
A.24. Release 6.3.2 ........................................................................................................................159
A.24.1. Changes ...................................................................................................................160
A.25. Release 6.3.1 ........................................................................................................................160
A.25.1. Changes ...................................................................................................................161
A.26. Release 6.3 ...........................................................................................................................162
A.26.1. Migration to version 6.3 ..........................................................................................163
A.26.2. Changes ...................................................................................................................163
A.27. Release 6.2.1 ........................................................................................................................166
A.27.1. Migration from version 6.2 to version 6.2.1............................................................167
A.27.2. Changes ...................................................................................................................167
A.28. Release 6.2 ...........................................................................................................................167
A.28.1. Migration from version 6.1 to version 6.2...............................................................167
A.28.2. Migration from version 1.x to version 6.2 ..............................................................168
A.28.3. Changes ...................................................................................................................168
A.29. Release 6.1.1 ........................................................................................................................170
A.29.1. Migration from version 6.1 to version 6.1.1............................................................170
A.29.2. Changes ...................................................................................................................170
A.30. Release 6.1 ...........................................................................................................................171
A.30.1. Migration to version 6.1 ..........................................................................................171
A.30.2. Changes ...................................................................................................................171
A.31. Release 6.0 ...........................................................................................................................173
A.31.1. Migration from version 1.09 to version 6.0.............................................................173
A.31.2. Migration from pre-1.09 to version 6.0...................................................................174
A.31.3. Changes ...................................................................................................................174
A.32. Release 1.09 .........................................................................................................................176
A.33. Release 1.02 .........................................................................................................................176
A.33.1. Migration from version 1.02 to version 1.02.1........................................................176
A.33.2. Dump/Reload Procedure..........................................................................................177
A.33.3. Changes ...................................................................................................................177
A.34. Release 1.01 .........................................................................................................................178
A.34.1. Migration from version 1.0 to version 1.01.............................................................178
A.34.2. Changes ...................................................................................................................180
A.35. Release 1.0 ...........................................................................................................................180
A.35.1. Changes ...................................................................................................................180
A.36. Postgres95 Release 0.03.......................................................................................................181
A.36.1. Changes ...................................................................................................................181
A.37. Postgres95 Release 0.02.......................................................................................................183
A.37.1. Changes ...................................................................................................................184
A.38. Postgres95 Release 0.01.......................................................................................................184
viii
Bibliography...........................................................................................................................................186
Index........................................................................................................................................................188
ix
List of Tables
3-1. pg_settings Columns ..........................................................................................................................24
3-2. Short option key .................................................................................................................................37
3-3. System V IPC parameters...................................................................................................................38
7-1. Character Set Encodings ....................................................................................................................68
7-2. Client/Server Character Set Encodings..............................................................................................70
10-1. Standard Statistics Views .................................................................................................................89
10-2. Statistics Access Functions ..............................................................................................................90
10-3. Lock Status System View.................................................................................................................93
List of Examples
6-1. An example pg_hba.conf file..........................................................................................................58
6-2. An example pg_ident.conf file .....................................................................................................63
x
Preface
1. What is PostgreSQL?
PostgreSQL is an object-relational database management system (ORDBMS) based on POSTGRES,
Version 4.2
1
, developed at the University of California at Berkeley Computer Science Department. The
POSTGRES project, led by Professor Michael Stonebraker, was sponsored by the Defense Advanced
Research Projects Agency (DARPA), the Army Research Office (ARO), the National Science Foundation
(NSF), and ESL, Inc.
PostgreSQL is an open-source descendant of this original Berkeley code. It provides SQL92/SQL99 lan-
guage support and other modern features.
POSTGRES pioneered many of the object-relational concepts now becoming available in some commer-
cial databases. Traditional relational database management systems (RDBMS) support a data model con-
sisting of a collection of named relations, containing attributes of a specific type. In current commercial
systems, possible types include floating point numbers, integers, character strings, money, and dates. It is
commonly recognized that this model is inadequate for future data-processing applications. The relational
model successfully replaced previous models in part because of its “Spartan simplicity”. However, this
simplicity makes the implementation of certain applications very difficult. PostgreSQL offers substantial
additional power by incorporating the following additional concepts in such a way that users can easily
extend the system:
• inheritance
• data types
• functions
Other features provide additional power and flexibility:
• constraints
• triggers
• rules
• transactional integrity
These features put PostgreSQL into the category of databases referred to as object-relational. Note that
this is distinct from those referred to as object-oriented, which in general are not as well suited to support-
ing traditional relational database languages. So, although PostgreSQL has some object-oriented features,
it is firmly in the relational database world. In fact, some commercial databases have recently incorporated
features pioneered by PostgreSQL.
1. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/postgres.html
i
Preface
2. A Short History of PostgreSQL
The object-relational database management system now known as PostgreSQL (and briefly called Post-
gres95) is derived from the POSTGRES package written at the University of California at Berkeley. With
over a decade of development behind it, PostgreSQL is the most advanced open-source database available
anywhere, offering multiversion concurrency control, supporting almost all SQL constructs (including
subselects, transactions, and user-defined types and functions), and having a wide range of language bind-
ings available (including C, C++, Java, Perl, Tcl, and Python).
2.1. The Berkeley POSTGRES Project
Implementation of the POSTGRES DBMS began in 1986. The initial concepts for the system were pre-
sented in The design of POSTGRES and the definition of the initial data model appeared in The POST-
GRES data model. The design of the rule system at that time was described in The design of the POST-
GRES rules system. The rationale and architecture of the storage manager were detailed in The design of
the POSTGRES storage system.
Postgres has undergone several major releases since then. The first “demoware” system became opera-
tional in 1987 and was shown at the 1988 ACM-SIGMOD Conference. Version 1, described in The im-
plementation of POSTGRES, was released to a few external users in June 1989. In response to a critique
of the first rule system (A commentary on the POSTGRES rules system), the rule system was redesigned
(On Rules, Procedures, Caching and Views in Database Systems) and Version 2 was released in June 1990
with the new rule system. Version 3 appeared in 1991 and added support for multiple storage managers,
an improved query executor, and a rewritten rewrite rule system. For the most part, subsequent releases
until Postgres95 (see below) focused on portability and reliability.
POSTGRES has been used to implement many different research and production applications. These in-
clude: a financial data analysis system, a jet engine performance monitoring package, an asteroid tracking
database, a medical information database, and several geographic information systems. POSTGRES has
also been used as an educational tool at several universities. Finally, Illustra Information Technologies
(later merged into Informix
2
, which is now owned by IBM
3
.) picked up the code and commercialized it.
POSTGRES became the primary data manager for the Sequoia 2000
4
scientific computing project in late
1992.
The size of the external user community nearly doubled during 1993. It became increasingly obvious that
maintenance of the prototype code and support was taking up large amounts of time that should have been
devoted to database research. In an effort to reduce this support burden, the Berkeley POSTGRES project
officially ended with Version 4.2.
2.2. Postgres95
In 1994, Andrew Yu and Jolly Chen added a SQL language interpreter to POSTGRES. Postgres95 was
subsequently released to the Web to find its own way in the world as an open-source descendant of the
original POSTGRES Berkeley code.
Postgres95 code was completely ANSI C and trimmed in size by 25%. Many internal changes improved
performance and maintainability. Postgres95 release 1.0.x ran about 30-50% faster on the Wisconsin
2. http://www.informix.com/
3. http://www.ibm.com/
4. http://meteora.ucsd.edu/s2k/s2k_home.html
ii
Preface
Benchmark compared to POSTGRES, Version 4.2. Apart from bug fixes, the following were the major
enhancements:
• The query language PostQUEL was replaced with SQL (implemented in the server). Subqueries were
not supported until PostgreSQL (see below), but they could be imitated in Postgres95 with user-defined
SQL functions. Aggregates were re-implemented. Support for the GROUP BY query clause was also
added. The libpq interface remained available for C programs.
• In addition to the monitor program, a new program (psql) was provided for interactive SQL queries
using GNU Readline.
• A new front-end library, libpgtcl, supported Tcl-based clients. A sample shell, pgtclsh, provided
new Tcl commands to interface Tcl programs with the Postgres95 backend.
• The large-object interface was overhauled. The Inversion large objects were the only mechanism for
storing large objects. (The Inversion file system was removed.)
• The instance-level rule system was removed. Rules were still available as rewrite rules.
• A short tutorial introducing regular SQL features as well as those of Postgres95 was distributed with
the source code
• GNU make (instead of BSD make) was used for the build. Also, Postgres95 could be compiled with an
unpatched GCC (data alignment of doubles was fixed).
2.3. PostgreSQL
By 1996, it became clear that the name “Postgres95” would not stand the test of time. We chose a new
name, PostgreSQL, to reflect the relationship between the original POSTGRES and the more recent ver-
sions with SQL capability. At the same time, we set the version numbering to start at 6.0, putting the
numbers back into the sequence originally begun by the Berkeley POSTGRES project.
The emphasis during development of Postgres95 was on identifying and understanding existing problems
in the backend code. With PostgreSQL, the emphasis has shifted to augmenting features and capabilities,
although work continues in all areas.
Major enhancements in PostgreSQL include:
• Table-level locking has been replaced by multiversion concurrency control, which allows readers to
continue reading consistent data during writer activity and enables hot backups from pg_dump while
the database stays available for queries.
• Important backend features, including subselects, defaults, constraints, and triggers, have been imple-
mented.
• Additional SQL92-compliant language features have been added, including primary keys, quoted iden-
tifiers, literal string type coercion, type casting, and binary and hexadecimal integer input.
• Built-in types have been improved, including new wide-range date/time types and additional geometric
type support.
• Overall backend code speed has been increased by approximately 20-40%, and backend start-up time
has decreased by 80% since version 6.0 was released.
iii
Preface
3. What’s In This Book
This book covers topics that are of interest to a PostgreSQL database administrator. This includes in-
stallation of the software, set up and configuration of the server, management of users and databases,
and maintenance tasks. Anyone who runs a PostgreSQL server, either for personal use, but especially in
production, should be familiar with the topics covered in this book.
The information in this book is arranged approximately in the order in which a new user should read it.
But the chapters are self-contained and can be read individually as desired. The information in this book is
presented in a narrative fashion in topical units. Readers looking for a complete description of a particular
command should look into the PostgreSQL Reference Manual.
The first few chapters are written so that they can be understood without prerequisite knowledge, so that
new users who need to set up their own server can begin their exploration with this book. The rest of this
book which is about tuning and management presupposes that the reader is familiar with the general use
of the PostgreSQL database system. Readers are encouraged to look at the PostgreSQL Tutorial and the
PostgreSQL User’s Guide for additional information.
This book covers PostgreSQL 7.3.2 only. For information on other versions, please read the documentation
that accompanies that release.
4. Overview of Documentation Resources
The PostgreSQL documentation is organized into several books:
PostgreSQL Tutorial
An informal introduction for new users.
PostgreSQL User’s Guide
Documents the SQL query language environment, including data types and functions, as well as
user-level performance tuning. Every PostgreSQL user should read this.
PostgreSQL Administrator’s Guide
Installation and server management information. Everyone who runs a PostgreSQL server, either for
personal use or for other users, needs to read this.
PostgreSQL Programmer’s Guide
Advanced information for application programmers. Topics include type and function extensibility,
library interfaces, and application design issues.
PostgreSQL Reference Manual
Reference pages for SQL command syntax, and client and server programs. This book is auxiliary to
the User’s, Administrator’s, and Programmer’s Guides.
PostgreSQL Developer’s Guide
Information for PostgreSQL developers. This is intended for those who are contributing to the Post-
greSQL project; application development information appears in the Programmer’s Guide.
iv
Preface
In addition to this manual set, there are other resources to help you with PostgreSQL installation and use:
man pages
The Reference Manual’s pages in the traditional Unix man format. There is no difference in content.
FAQs
Frequently Asked Questions (FAQ) lists document both general issues and some platform-specific
issues.
READMEs
README files are available for some contributed packages.
Web Site
The PostgreSQL web site
5
carries details on the latest release, upcoming features, and other informa-
tion to make your work or play with PostgreSQL more productive.
Mailing Lists
The mailing lists are a good place to have your questions answered, to share experiences with other
users, and to contact the developers. Consult the User’s Lounge
6
section of the PostgreSQL web site
for details.
Yourself!
PostgreSQL is an open-source effort. As such, it depends on the user community for ongoing support.
As you begin to use PostgreSQL, you will rely on others for help, either through the documentation or
through the mailing lists. Consider contributing your knowledge back. If you learn something which
is not in the documentation, write it up and contribute it. If you add features to the code, contribute
them.
Even those without a lot of experience can provide corrections and minor changes in the documenta-
to get going.
5. Terminology and Notation
An administrator is generally a person who is in charge of installing and running the server. A user
could be anyone who is using, or wants to use, any part of the PostgreSQL system. These terms should
not be interpreted too narrowly; this documentation set does not have fixed presumptions about system
administration procedures.
We use /usr/local/pgsql/ as the root directory of the installation and /usr/local/pgsql/data as
the directory with the database files. These directories may vary on your site, details can be derived in the
Administrator’s Guide.
5. http://www.postgresql.org
6. http://www.postgresql.org/users-lounge/
v
Preface
In a command synopsis, brackets ([ and ]) indicate an optional phrase or keyword. Anything in braces ({
and }) and containing vertical bars (|) indicates that you must choose one alternative.
Examples will show commands executed from various accounts and programs. Commands executed from
a Unix shell may be preceded with a dollar sign (“$”). Commands executed from particular user accounts
such as root or postgres are specially flagged and explained. SQL commands may be preceded with “=>”
or will have no leading prompt, depending on the context.
Note: The notation for flagging commands is not universally consistent throughout the documentation
set. Please report problems to the documentation mailing list <[email protected]>.
6. Bug Reporting Guidelines
When you find a bug in PostgreSQL we want to hear about it. Your bug reports play an important part
in making PostgreSQL more reliable because even the utmost care cannot guarantee that every part of
PostgreSQL will work on every platform under every circumstance.
The following suggestions are intended to assist you in forming bug reports that can be handled in an
effective fashion. No one is required to follow them but it tends to be to everyone’s advantage.
We cannot promise to fix every bug right away. If the bug is obvious, critical, or affects a lot of users,
chances are good that someone will look into it. It could also happen that we tell you to update to a newer
version to see if the bug happens there. Or we might decide that the bug cannot be fixed before some
major rewrite we might be planning is done. Or perhaps it is simply too hard and there are more important
things on the agenda. If you need help immediately, consider obtaining a commercial support contract.
6.1. Identifying Bugs
Before you report a bug, please read and re-read the documentation to verify that you can really do
whatever it is you are trying. If it is not clear from the documentation whether you can do something or
not, please report that too; it is a bug in the documentation. If it turns out that the program does something
different from what the documentation says, that is a bug. That might include, but is not limited to, the
following circumstances:
• A program terminates with a fatal signal or an operating system error message that would point to a
problem in the program. (A counterexample might be a “disk full” message, since you have to fix that
yourself.)
• A program produces the wrong output for any given input.
• A program refuses to accept valid input (as defined in the documentation).
• A program accepts invalid input without a notice or error message. But keep in mind that your idea of
invalid input might be our idea of an extension or compatibility with traditional practice.
• PostgreSQL fails to compile, build, or install according to the instructions on supported platforms.
Here “program” refers to any executable, not only the backend server.
vi
Preface
Being slow or resource-hogging is not necessarily a bug. Read the documentation or ask on one of the
mailing lists for help in tuning your applications. Failing to comply to the SQL standard is not necessarily
a bug either, unless compliance for the specific feature is explicitly claimed.
Before you continue, check on the TODO list and in the FAQ to see if your bug is already known. If you
cannot decode the information on the TODO list, report your problem. The least we can do is make the
TODO list clearer.
6.2. What to report
The most important thing to remember about bug reporting is to state all the facts and only facts. Do not
speculate what you think went wrong, what “it seemed to do”, or which part of the program has a fault.
If you are not familiar with the implementation you would probably guess wrong and not help us a bit.
And even if you are, educated explanations are a great supplement to but no substitute for facts. If we are
going to fix the bug we still have to see it happen for ourselves first. Reporting the bare facts is relatively
straightforward (you can probably copy and paste them from the screen) but all too often important details
are left out because someone thought it does not matter or the report would be understood anyway.
The following items should be contained in every bug report:
• The exact sequence of steps from program start-up necessary to reproduce the problem. This should
be self-contained; it is not enough to send in a bare select statement without the preceding create table
and insert statements, if the output should depend on the data in the tables. We do not have the time
to reverse-engineer your database schema, and if we are supposed to make up our own data we would
probably miss the problem. The best format for a test case for query-language related problems is a file
that can be run through the psql frontend that shows the problem. (Be sure to not have anything in your
~/.psqlrc start-up file.) An easy start at this file is to use pg_dump to dump out the table declarations
and data needed to set the scene, then add the problem query. You are encouraged to minimize the size
of your example, but this is not absolutely necessary. If the bug is reproducible, we will find it either
way.
If your application uses some other client interface, such as PHP, then please try to isolate the offending
queries. We will probably not set up a web server to reproduce your problem. In any case remember
to provide the exact input files, do not guess that the problem happens for “large files” or “mid-size
databases”, etc. since this information is too inexact to be of use.
• The output you got. Please do not say that it “didn’t work” or “crashed”. If there is an error message,
show it, even if you do not understand it. If the program terminates with an operating system error,
say which. If nothing at all happens, say so. Even if the result of your test case is a program crash or
otherwise obvious it might not happen on our platform. The easiest thing is to copy the output from the
terminal, if possible.
Note: In case of fatal errors, the error message reported by the client might not contain all the
information available. Please also look at the log output of the database server. If you do not keep
your server’s log output, this would be a good time to start doing so.
vii
Preface
• The output you expected is very important to state. If you just write “This command gives me that
output.” or “This is not what I expected.”, we might run it ourselves, scan the output, and think it
looks OK and is exactly what we expected. We should not have to spend the time to decode the exact
semantics behind your commands. Especially refrain from merely saying that “This is not what SQL
says/Oracle does.” Digging out the correct behavior from SQL is not a fun undertaking, nor do we all
know how all the other relational databases out there behave. (If your problem is a program crash, you
can obviously omit this item.)
• Any command line options and other start-up options, including concerned environment variables or
configuration files that you changed from the default. Again, be exact. If you are using a prepackaged
distribution that starts the database server at boot time, you should try to find out how that is done.
• Anything you did at all differently from the installation instructions.
• The PostgreSQL version. You can run the command SELECT version(); to find out the version of
the server you are connected to. Most executable programs also support a --version option; at least
postmaster --version and psql --version should work. If the function or the options do not
exist then your version is more than old enough to warrant an upgrade. You can also look into the
README file in the source directory or at the name of your distribution file or package name. If you run
a prepackaged version, such as RPMs, say so, including any subversion the package may have. If you
are talking about a CVS snapshot, mention that, including its date and time.
If your version is older than 7.3.2 we will almost certainly tell you to upgrade. There are tons of bug
fixes in each new release, that is why we make new releases.
• Platform information. This includes the kernel name and version, C library, processor, memory infor-
mation. In most cases it is sufficient to report the vendor and version, but do not assume everyone knows
what exactly “Debian” contains or that everyone runs on Pentiums. If you have installation problems
then information about compilers, make, etc. is also necessary.
Do not be afraid if your bug report becomes rather lengthy. That is a fact of life. It is better to report
everything the first time than us having to squeeze the facts out of you. On the other hand, if your input
files are huge, it is fair to ask first whether somebody is interested in looking into it.
Do not spend all your time to figure out which changes in the input make the problem go away. This will
probably not help solving it. If it turns out that the bug cannot be fixed right away, you will still have time
to find and share your work-around. Also, once again, do not waste your time guessing why the bug exists.
We will find that out soon enough.
When writing a bug report, please choose non-confusing terminology. The software package in total is
called “PostgreSQL”, sometimes “Postgres” for short. If you are specifically talking about the backend
server, mention that, do not just say “PostgreSQL crashes”. A crash of a single backend server process is
quite different from crash of the parent “postmaster” process; please don’t say “the postmaster crashed”
when you mean a single backend went down, nor vice versa. Also, client programs such as the interactive
frontend “psql” are completely separate from the backend. Please try to be specific about whether the
problem is on the client or server side.
6.3. Where to report bugs
viii
Preface
requested to use a descriptive subject for your email message, perhaps parts of the error message.
Another method is to fill in the bug report web-form available at the project’s web site
http://www.postgresql.org/. Entering a bug report this way causes it to be mailed to the
<[email protected]> mailing list.
subscribers normally do not wish to receive bug reports. More importantly, they are unlikely to fix them.
This list is for discussing the development of PostgreSQL and it would be nice if we could keep the bug
reports separate. We might choose to take up a discussion about your bug report on pgsql-hackers, if
the problem needs more review.
If you have a problem with the documentation, the best place to report it is the documentation mailing
unhappy with.
If your bug is a portability problem on a non-supported platform, send mail to
platform.
Note: Due to the unfortunate amount of spam going around, all of the above email addresses are
closed mailing lists. That is, you need to be subscribed to a list to be allowed to post on it. (You need
not be subscribed to use the bug report web-form, however.) If you would like to send mail but do not
want to receive list traffic, you can subscribe and set your subscription option to nomail. For more
information send mail to <[email protected]> with the single word help in the body of the
message.
ix
Chapter 1. Installation Instructions
This chapter describes the installation of PostgreSQL from the source code distribution.
1.1. Short Version
./configure
gmake
su
gmake install
adduser postgres
mkdir /usr/local/pgsql/data
chown postgres /usr/local/pgsql/data
su - postgres
/usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
/usr/local/pgsql/bin/postmaster -D /usr/local/pgsql/data >logfile 2>&1 &
/usr/local/pgsql/bin/createdb test
/usr/local/pgsql/bin/psql test
The long version is the rest of this chapter.
1.2. Requirements
In general, a modern Unix-compatible platform should be able to run PostgreSQL. The platforms that had
received specific testing at the time of release are listed in Section 1.7 below. In the doc subdirectory of
the distribution there are several platform-specific FAQ documents you might wish to consult if you are
having trouble.
The following software packages are required for building PostgreSQL:
• GNU make is required; other make programs will not work. GNU make is often installed under the
name gmake; this document will always refer to it by that name. (On some systems GNU make is the
default tool with the name make.) To test for GNU make enter
gmake --version
It is recommended to use version 3.76.1 or later.
• You need an ISO/ANSI C compiler. Recent versions of GCC are recommendable, but PostgreSQL is
known to build with a wide variety of compilers from different vendors.
• gzip is needed to unpack the distribution in the first place. If you are reading this, you probably already
got past that hurdle.
• The GNU Readline library (for comfortable line editing and command history retrieval) will be used
by default. If you don’t want to use it then you must specify the --without-readline option for
configure. (On NetBSD, the libedit library is readline-compatible and is used if libreadline is
not found.)
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Chapter 1. Installation Instructions
• To build on Windows NT or Windows 2000 you need the Cygwin and cygipc packages. See the file
doc/FAQ_MSWIN for details.
The following packages are optional. They are not required in the default configuration, but they are
needed when certain build options are enabled, as explained below.
• To build the server programming language PL/Perl you need a full Perl installation, including the
libperl library and the header files. Since PL/Perl will be a shared library, the libperl library
must be a shared library also on most platforms. This appears to be the default in recent Perl versions,
but it was not in earlier versions, and in general it is the choice of whomever installed Perl at your site.
If you don’t have the shared library but you need one, a message like this will appear during the build
to point out this fact:
*** Cannot build PL/Perl because libperl is not a shared library.
*** You might have to rebuild your Perl installation. Refer to
*** the documentation for details.
(If you don’t follow the on-screen output you will merely notice that the PL/Perl library object,
plperl.so or similar, will not be installed.) If you see this, you will have to rebuild and install Perl
manually to be able to build PL/Perl. During the configuration process for Perl, request a shared
library.
• To build the Python interface module or the PL/Python server programming language, you need a
Python installation, including the header files. Since PL/Python will be a shared library, the libpython
library must be a shared library also on most platforms. This is not the case in a default Python instal-
lation.
If after building and installing you have a file called plpython.so (possibly a different extension),
then everything went well. Otherwise you should have seen a notice like this flying by:
*** Cannot build PL/Python because libpython is not a shared library.
*** You might have to rebuild your Python installation. Refer to
*** the documentation for details.
That means you have to rebuild (part of) your Python installation to supply this shared library.
The catch is that the Python distribution or the Python maintainers do not provide any direct way to do
this. The closest thing we can offer you is the information in Python FAQ 3.30
1
. On some operating sys-
tems you don’t really have to build a shared library, but then you will have to convince the PostgreSQL
build system of this. Consult the Makefile in the src/pl/plpython directory for details.
• If you want to build Tcl or Tk components (clients and the PL/Tcl language) you of course need a Tcl
installation.
• To build the JDBC driver, you need Ant 1.5 or higher and a JDK. Ant is a special tool for building
Java-based packages. It can be downloaded from the Ant web site
2
.
1. http://www.python.org/doc/FAQ.html#3.30
2. http://jakarta.apache.org/ant/index.html
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Chapter 1. Installation Instructions
If you have several Java compilers installed, it depends on the Ant configuration which one gets used.
Precompiled Ant distributions are typically set up to read a file .antrc in the current user’s home
directory for configuration. For example, to use a different JDK than the default, this may work:
JAVA_HOME=/usr/local/sun-jdk1.3
JAVACMD=$JAVA_HOME/bin/java
Note: Do not try to build the driver by calling ant or even javac directly. This will not work. Run
gmake normally as described below.
• To enable Native Language Support (NLS), that is, the ability to display a program’s messages in a
language other than English, you need an implementation of the Gettext API. Some operating sys-
tems have this built-in (e.g., Linux, NetBSD, Solaris), for other systems you can download an add-on
package from here: http://www.postgresql.org/~petere/gettext.html. If you are using the gettext imple-
mentation in the GNU C library then you will additionally need the GNU Gettext package for some
utility programs. For any of the other implementations you will not need it.
• Kerberos, OpenSSL, or PAM, if you want to support authentication using these services.
If you are build from a CVS tree instead of using a released source package, or if you want to do develop-
ment, you also need the following packages:
• Flex and Bison are needed to build a CVS checkout or if you changed the actual scanner and parser
definition files. If you need them, be sure to get Flex 2.5.4 or later and Bison 1.50 or later. Other yacc
programs can sometimes be used, but doing so requires extra effort and is not recommended. Other lex
programs will definitely not work.
If you need to get a GNU package, you can find it at your local GNU mirror site (see
http://www.gnu.org/order/ftp.html for a list) or at ftp://ftp.gnu.org/gnu/.
Also check that you have sufficient disk space. You will need about 65 MB for the source tree during
compilation and about 15 MB for the installation directory. An empty database cluster takes about 25
MB, databases take about five times the amount of space that a flat text file with the same data would take.
If you are going to run the regression tests you will temporarily need up to an extra 90 MB. Use the df
command to check for disk space.
1.3. Getting The Source
The PostgreSQL 7.3.2 sources can be obtained by anonymous FTP from
ftp://ftp.postgresql.org/pub/postgresql-7.3.2.tar.gz. Use a mirror if possible. After you have obtained the
file, unpack it:
gunzip postgresql-7.3.2.tar.gz
tar xf postgresql-7.3.2.tar
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Chapter 1. Installation Instructions
This will create a directory postgresql-7.3.2 under the current directory with the PostgreSQL sources.
Change into that directory for the rest of the installation procedure.
1.4. If You Are Upgrading
The internal data storage format changes with new releases of PostgreSQL. Therefore, if you are up-
grading an existing installation that does not have a version number “7.3.x”, you must back up and
restore your data as shown here. These instructions assume that your existing installation is under the
/usr/local/pgsql directory, and that the data area is in /usr/local/pgsql/data. Substitute your
paths appropriately.
1. Make sure that your database is not updated during or after the backup. This does not affect the
integrity of the backup, but the changed data would of course not be included. If necessary, edit the
permissions in the file /usr/local/pgsql/data/pg_hba.conf (or equivalent) to disallow access
from everyone except you.
2. To back up your database installation, type:
pg_dumpall > outputfile
If you need to preserve OIDs (such as when using them as foreign keys), then use the -o option when
running pg_dumpall.
pg_dumpall does not save large objects. Check Section 9.1.4 if you need to do this.
To make the backup, you can use the pg_dumpall command from the version you are currently
running. For best results, however, try to use the pg_dumpall command from PostgreSQL 7.3.2,
since this version contains bug fixes and improvements over older versions. While this advice might
seem idiosyncratic since you haven’t installed the new version yet, it is advisable to follow it if you
plan to install the new version in parallel with the old version. In that case you can complete the
installation normally and transfer the data later. This will also decrease the downtime.
3. If you are installing the new version at the same location as the old one then shut down the old server,
at the latest before you install the new files:
kill -INT ‘cat /usr/local/pgsql/data/postmaster.pid‘
Versions prior to 7.0 do not have this postmaster.pid file. If you are using such a version you must
find out the process id of the server yourself, for example by typing ps ax | grep postmas-
ter, and supply it to the kill command.
On systems that have PostgreSQL started at boot time, there is probably a start-up file that will
accomplish the same thing. For example, on a Red Hat Linux system one might find that
/etc/rc.d/init.d/postgresql stop
works. Another possibility is pg_ctl stop.
4. If you are installing in the same place as the old version then it is also a good idea to move the old
installation out of the way, in case you have trouble and need to revert to it. Use a command like this:
mv /usr/local/pgsql /usr/local/pgsql.old
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Chapter 1. Installation Instructions
After you have installed PostgreSQL 7.3.2, create a new database directory and start the new server.
Remember that you must execute these commands while logged in to the special database user account
(which you already have if you are upgrading).
/usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
/usr/local/pgsql/bin/postmaster -D /usr/local/pgsql/data
Finally, restore your data with
/usr/local/pgsql/bin/psql -d template1 -f outputfile
using the new psql.
These topics are discussed at length in Section 9.3, which you are encouraged to read in any case.
1.5. Installation Procedure
1. Configuration
The first step of the installation procedure is to configure the source tree for your system and choose
the options you would like. This is done by running the configure script. For a default installation
simply enter
./configure
This script will run a number of tests to guess values for various system dependent variables and
detect some quirks of your operating system, and finally will create several files in the build tree to
record what it found. (You can also run configure in a directory outside the source tree if you want
to keep the build directory separate.)
The default configuration will build the server and utilities, as well as all client applications and
interfaces that require only a C compiler. All files will be installed under /usr/local/pgsql by
default.
You can customize the build and installation process by supplying one or more of the following
command line options to configure:
--prefix=PREFIX
Install all files under the directory PREFIX instead of /usr/local/pgsql. The actual files will
be installed into various subdirectories; no files will ever be installed directly into the PREFIX
directory.
If you have special needs, you can also customize the individual subdirectories with the follow-
ing options.
--exec-prefix=EXEC-PREFIX
You can install architecture-dependent files under a different prefix, EXEC-PREFIX, than what
PREFIX was set to. This can be useful to share architecture-independent files between hosts.
If you omit this, then EXEC-PREFIX is set equal to PREFIX and both architecture-dependent
and independent files will be installed under the same tree, which is probably what you want.
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Chapter 1. Installation Instructions
--bindir=DIRECTORY
Specifies the directory for executable programs. The default is EXEC-PREFIX/bin, which nor-
mally means /usr/local/pgsql/bin.
--datadir=DIRECTORY
Sets the directory for read-only data files used by the installed programs. The default is PRE-
FIX/share. Note that this has nothing to do with where your database files will be placed.
--sysconfdir=DIRECTORY
The directory for various configuration files, PREFIX/etc by default.
--libdir=DIRECTORY
The location to install libraries and dynamically loadable modules. The default is
EXEC-PREFIX/lib.
--includedir=DIRECTORY
The directory for installing C and C++ header files. The default is PREFIX/include.
--docdir=DIRECTORY
Documentation files, except “man” pages, will be installed into this directory. The default is
PREFIX/doc.
--mandir=DIRECTORY
The man pages that come with PostgreSQL will be installed under this directory, in their respec-
tive manx subdirectories. The default is PREFIX/man.
Note: Care has been taken to make it possible to install PostgreSQL into shared installation
locations (such as /usr/local/include) without interfering with the namespace of the rest of
the system. First, the string “/postgresql” is automatically appended to datadir, sysconfdir,
and docdir, unless the fully expanded directory name already contains the string “postgres”
or “pgsql”. For example, if you choose /usr/local as prefix, the documentation will be in-
stalled in /usr/local/doc/postgresql, but if the prefix is /opt/postgres, then it will be in
/opt/postgres/doc. The public C header files of the client interfaces are installed into in-
cludedir and are namespace-clean. The internal header files and the server header files are
installed into private directories under includedir. See the Programmer’s Guide for information
about how to get at the header files for each interface. Finally, a private subdirectory will also be
created, if appropriate, under libdir for dynamically loadable modules.
--with-includes=DIRECTORIES
DIRECTORIES is a colon-separated list of directories that will be added to the list the compiler
searches for header files. If you have optional packages (such as GNU Readline) installed in a
non-standard location, you have to use this option and probably also the corresponding --with-
libraries option.
Example: --with-includes=/opt/gnu/include:/usr/sup/include.
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Chapter 1. Installation Instructions
--with-libraries=DIRECTORIES
DIRECTORIES is a colon-separated list of directories to search for libraries. You will probably
have to use this option (and the corresponding --with-includes option) if you have packages
installed in non-standard locations.
Example: --with-libraries=/opt/gnu/lib:/usr/sup/lib.
--enable-recode
Enables single-byte character set recode support. See Section 7.3 about this feature. Note that
a more general form of character set conversion is supported in the default configuration; this
feature is obsolete.
--enable-nls[=LANGUAGES]
Enables Native Language Support (NLS), that is, the ability to display a program’s messages in
a language other than English. LANGUAGES is a space separated list of codes of the languages
that you want supported, for example --enable-nls=’de fr’. (The intersection between
your list and the set of actually provided translations will be computed automatically.) If you do
not specify a list, then all available translations are installed.
To use this option, you will need an implementation of the gettext API; see above.
--with-pgport=NUMBER
Set NUMBER as the default port number for server and clients. The default is 5432. The port can
always be changed later on, but if you specify it here then both server and clients will have the
same default compiled in, which can be very convenient. Usually the only good reason to select
a non-default value is if you intend to run multiple PostgreSQL servers on the same machine.
--with-perl
Build the PL/Perl server-side language.
--with-python
Build the Python interface module and the PL/Python server-side language. You need to have
root access to be able to install the Python module at its default place (/usr/lib/pythonx.y).
--with-tcl
Build components that require Tcl/Tk, which are libpgtcl, pgtclsh, pgtksh, and PL/Tcl. But see
below about --without-tk.
--without-tk
If you specify --with-tcl and this option, then the program that requires Tk (pgtksh) will be
excluded.
--with-tclconfig=DIRECTORY
--with-tkconfig=DIRECTORY
Tcl/Tk installs the files tclConfig.sh and tkConfig.sh, which contain configuration in-
formation needed to build modules interfacing to Tcl or Tk. These files are normally found
automatically at their well-known locations, but if you want to use a different version of Tcl or
Tk you can specify the directory in which to find them.
--with-java
Build the JDBC driver and associated Java packages.
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Chapter 1. Installation Instructions
--with-krb4[=DIRECTORY]
--with-krb5[=DIRECTORY]
Build with support for Kerberos authentication. You can use either Kerberos version 4 or 5, but
not both. The DIRECTORY argument specifies the root directory of the Kerberos installation;
/usr/athena is assumed as default. If the relevant header files and libraries are not under a
common parent directory, then you must use the --with-includes and --with-libraries
options in addition to this option. If, on the other hand, the required files are in a location that is
searched by default (e.g., /usr/lib), then you can leave off the argument.
configure will check for the required header files and libraries to make sure that your Kerberos
installation is sufficient before proceeding.
--with-krb-srvnam=NAME
The name of the Kerberos service principal. postgres is the default. There’s probably no reason
to change this.
--with-openssl[=DIRECTORY]
Build with support for SSL (encrypted) connections. This requires the OpenSSL package to be
installed. The DIRECTORY argument specifies the root directory of the OpenSSL installation;
the default is /usr/local/ssl.
configurewill check for the required header files and libraries to make sure that your OpenSSL
installation is sufficient before proceeding.
--with-pam
Build with PAM (Pluggable Authentication Modules) support.
--without-readline
Prevents the use of the Readline library. This disables command-line editing and history in psql,
so it is not recommended.
--without-zlib
Prevents the use of the Zlib library. This disables compression support in pg_dump. This option
is only intended for those rare systems where this library is not available.
--enable-debug
Compiles all programs and libraries with debugging symbols. This means that you can run the
programs through a debugger to analyze problems. This enlarges the size of the installed exe-
cutables considerably, and on non-GCC compilers it usually also disables compiler optimization,
causing slowdowns. However, having the symbols available is extremely helpful for dealing with
any problems that may arise. Currently, this option is recommended for production installations
only if you use GCC. But you should always have it on if you are doing development work or
running a beta version.
--enable-cassert
Enables assertion checks in the server, which test for many “can’t happen” conditions. This is
invaluable for code development purposes, but the tests slow things down a little. Also, having
the tests turned on won’t necessarily enhance the stability of your server! The assertion checks
are not categorized for severity, and so what might be a relatively harmless bug will still lead
8
Chapter 1. Installation Instructions
to server restarts if it triggers an assertion failure. Currently, this option is not recommended for
production use, but you should have it on for development work or when running a beta version.
--enable-depend
Enables automatic dependency tracking. With this option, the makefiles are set up so that all
affected object files will be rebuilt when any header file is changed. This is useful if you are
doing development work, but is just wasted overhead if you intend only to compile once and
install. At present, this option will work only if you use GCC.
If you prefer a C compiler different from the one configure picks then you can set the environment
variable CC to the program of your choice. By default, configure will pick gcc unless this is in-
appropriate for the platform. Similarly, you can override the default compiler flags with the CFLAGS
variable.
You can specify environment variables on the configure command line, for example:
./configure CC=/opt/bin/gcc CFLAGS=’-O2 -pipe’
2. Build
To start the build, type
gmake
(Remember to use GNU make.) The build may take anywhere from 5 minutes to half an hour de-
pending on your hardware. The last line displayed should be
All of PostgreSQL is successfully made. Ready to install.
3. Regression Tests
If you want to test the newly built server before you install it, you can run the regression tests at this
point. The regression tests are a test suite to verify that PostgreSQL runs on your machine in the way
the developers expected it to. Type
gmake check
(This won’t work as root; do it as an unprivileged user.) It is possible that some tests fail, due to
differences in error message wording or floating point results. Chapter 13 contains detailed informa-
tion about interpreting the test results. You can repeat this test at any later time by issuing the same
command.
4. Installing The Files
Note: If you are upgrading an existing system and are going to install the new files over the
old ones, then you should have backed up your data and shut down the old server by now, as
explained in Section 1.4 above.
To install PostgreSQL enter
9
Chapter 1. Installation Instructions
gmake install
This will install files into the directories that were specified in step 1. Make sure that you have appro-
priate permissions to write into that area. Normally you need to do this step as root. Alternatively, you
could create the target directories in advance and arrange for appropriate permissions to be granted.
You can use gmake install-strip instead of gmake install to strip the executable files and
libraries as they are installed. This will save some space. If you built with debugging support, stripping
will effectively remove the debugging support, so it should only be done if debugging is no longer
needed. install-strip tries to do a reasonable job saving space, but it does not have perfect
knowledge of how to strip every unneeded byte from an executable file, so if you want to save all the
disk space you possibly can, you will have to do manual work.
If you built the Python interfaces and you were not the root user when you executed the above com-
mand then that part of the installation probably failed. In that case you should become the root user
and then do
gmake -C src/interfaces/python install
If you do not have superuser access you are on your own: you can still take the required files and
place them in other directories where Python can find them, but how to do that is left as an exercise.
The standard installation provides only the header files needed for client application development. If
you plan to do any server-side program development (such as custom functions or data types written in
C), then you may want to install the entire PostgreSQL include tree into your target include directory.
To do that, enter
gmake install-all-headers
This adds a megabyte or two to the installation footprint, and is only useful if you don’t plan to keep
the whole source tree around for reference. (If you do, you can just use the source’s include directory
when building server-side software.)
Client-only installation: If you want to install only the client applications and interface libraries,
then you can use these commands:
gmake -C src/bin install
gmake -C src/include install
gmake -C src/interfaces install
gmake -C doc install
Uninstallation: To undo the installation use the command gmake uninstall. However, this will not
remove any created directories.
Cleaning: After the installation you can make room by removing the built files from the source tree with
the command gmake clean. This will preserve the files made by the configure program, so that you can
rebuild everything with gmake later on. To reset the source tree to the state in which it was distributed, use
gmake distclean. If you are going to build for several platforms from the same source tree you must
do this and re-configure for each build.
If you perform a build and then discover that your configure options were wrong, or if you change anything
that configure investigates (for example, software upgrades), then it’s a good idea to do gmake dist-
clean before reconfiguring and rebuilding. Without this, your changes in configuration choices may not
propagate everywhere they need to.
10
Chapter 1. Installation Instructions
1.6. Post-Installation Setup
1.6.1. Shared Libraries
On some systems that have shared libraries (which most systems do) you need to tell your system how
to find the newly installed shared libraries. The systems on which this is not necessary include BSD/OS,
FreeBSD, HP-UX, IRIX, Linux, NetBSD, OpenBSD, Tru64 UNIX (formerly Digital UNIX), and Solaris.
The method to set the shared library search path varies between platforms, but the most widely usable
method is to set the environment variable LD_LIBRARY_PATH like so: In Bourne shells (sh, ksh, bash,
zsh)
LD_LIBRARY_PATH=/usr/local/pgsql/lib
export LD_LIBRARY_PATH
or in csh or tcsh
setenv LD_LIBRARY_PATH /usr/local/pgsql/lib
Replace /usr/local/pgsql/lib with whatever you set --libdir to in step 1. You should put these
commands into a shell start-up file such as /etc/profile or ~/.bash_profile. Some good informa-
tion about the caveats associated with this method can be found at http://www.visi.com/~barr/ldpath.html.
On some systems it might be preferable to set the environment variable LD_RUN_PATH before building.
On Cygwin, put the library directory in the PATH or move the .dll files into the bin/ directory.
If in doubt, refer to the manual pages of your system (perhaps ld.soor rld). If you later on get a message
like
psql: error in loading shared libraries
libpq.so.2.1: cannot open shared object file: No such file or directory
then this step was necessary. Simply take care of it then.
If you are on BSD/OS, Linux, or SunOS 4 and you have root access you can run
/sbin/ldconfig /usr/local/pgsql/lib
(or equivalent directory) after installation to enable the run-time linker to find the shared libraries faster.
Refer to the manual page of ldconfig for more information. On FreeBSD, NetBSD, and OpenBSD the
command is
/sbin/ldconfig -m /usr/local/pgsql/lib
instead. Other systems are not known to have an equivalent command.
1.6.2. Environment Variables
If you installed into /usr/local/pgsql or some other location that is not searched for programs by
default, you should add /usr/local/pgsql/bin (or whatever you set --bindir to in step 1) into your
PATH. Strictly speaking, this is not necessary, but it will make the use of PostgreSQL much more conve-
nient.
11
Chapter 1. Installation Instructions
To do this, add the following to your shell start-up file, such as ~/.bash_profile (or /etc/profile,
if you want it to affect every user):
PATH=/usr/local/pgsql/bin:$PATH
export PATH
If you are using csh or tcsh, then use this command:
set path = ( /usr/local/pgsql/bin $path )
To enable your system to find the man documentation, you need to add a line like the following to a shell
start-up file unless you installed into a location that is searched by default.
MANPATH=/usr/local/pgsql/man:$MANPATH
export MANPATH
The environment variables PGHOST and PGPORT specify to client applications the host and port of the
database server, overriding the compiled-in defaults. If you are going to run client applications remotely
then it is convenient if every user that plans to use the database sets PGHOST. This is not required, however:
the settings can be communicated via command line options to most client programs.
1.7. Supported Platforms
PostgreSQL has been verified by the developer community to work on the platforms listed below. A
supported platform generally means that PostgreSQL builds and installs according to these instructions
and that the regression tests pass.
Note: If you are having problems with the installation on a supported platform, please write to <pgsql-
OS Processor Version Reported Remarks
AIX RS6000 7.3 2002-11-12,
Andreas
Zeugswetter
see also
doc/FAQ_AIX
BSD/OS x86 7.3 2002-10-25, Bruce
Momjian
4.2
12
Chapter 1. Installation Instructions
OS Processor Version Reported Remarks
FreeBSD Alpha 7.3 2002-11-13, Chris
Kings-Lynne
FreeBSD x86 7.3 2002-10-29, 3.3,
Nigel J. Andrews
(<[email protected]>),
4.7, Larry
Rosenman
(<[email protected]>),
5.0, Sean
Chittenden
HP-UX PA-RISC 7.3 2002-10-28, 10.20
Tom Lane
(<[email protected]>),
11.00, 11.11, 32 &
64 bit, Giles Lean
gcc and cc; see also
doc/FAQ_HPUX
IRIX MIPS 7.3 2002-10-27, Ian
Barwick
Irix64 Komma 6.5
Linux Alpha 7.3 2002-10-28,
Magnus Naeslund
2.4.19-pre6
Linux PlayStation 2 7.3 2002-11-19,
Permaine Cheung
#undef
HAS_TEST_AND_SET,
remove slock_t
typedef
Linux PPC74xx 7.3 2002-10-26, Tom
Lane
bye 2.2.18; Apple
G3
Linux S/390 7.3 2002-11-22,
Permaine Cheung
both s390 and
s390x (32 and 64
bit)
Linux Sparc 7.3 2002-10-26, Doug
McNaught
3.0
13
Chapter 1. Installation Instructions
OS Processor Version Reported Remarks
Linux x86 7.3 2002-10-26, Alvaro
Herrera
2.4
MacOS X PPC 7.3 2002-10-28, 10.1,
Tom Lane
(<[email protected]>),
10.2.1, Adam
Witney
NetBSD arm32 7.3 2002-11-19, Patrick
Welche
1.6
NetBSD x86 7.3 2002-11-14, Patrick
Welche
1.6
OpenBSD Sparc 7.3 2002-11-17,
Christopher
Kings-Lynne
3.2
OpenBSD x86 7.3 2002-11-14, 3.1
Magnus Naeslund
(<[email protected]>),
3.2 Christopher
Kings-Lynne
SCO OpenServer 5 x86 7.3.1 2002-12-11,
Shibashish Satpathy
5.0.4, gcc; see also
doc/FAQ_SCO
Solaris Sparc 7.3 2002-10-28,
Andrew Sullivan
Solaris 7 & 8; see
also
doc/FAQ_Solaris
Solaris x86 7.3 2002-11-20, Martin
Renters
5.8; see also
doc/FAQ_Solaris
14
Chapter 1. Installation Instructions
OS Processor Version Reported Remarks
Tru64 UNIX Alpha 7.3 2002-11-05,
Alessio Bragadini
UnixWare x86 7.3 2002-11-01, 7.1.3
Larry Rosenman
(<[email protected]>),
7.1.1 and
7.1.2(8.0.0) Olivier
Prenant
see also
doc/FAQ_SCO
Windows x86 7.3 2002-10-29, Dave
Page
(<dpage@vale-
housing.co.uk>),
Jason Tishler
with Cygwin; see
doc/FAQ_MSWIN
Windows x86 7.3 2002-11-05, Dave
Page
(<dpage@vale-
housing.co.uk>)
native is client-side
only; see Chapter 2
Unsupported Platforms: The following platforms are either known not to work, or they used to work in
a previous release and we did not receive explicit confirmation of a successful test with version 7.3 at the
time this list was compiled. We include these here to let you know that these platforms could be supported
if given some attention.
OS Processor Version Reported Remarks
BeOS x86 7.2 2001-11-29, Cyril
Velter
needs updates to
semaphore code
DG/UX 5.4R4.11 m88k 6.3 1998-03-01, Brian
E Gallew
no recent reports
Linux armv4l 7.2 2001-12-10, Mark
Knox
2.2.x
15
Chapter 1. Installation Instructions
OS Processor Version Reported Remarks
Linux MIPS 7.2 2001-11-15, Hisao
Shibuya
2.0.x; Cobalt Qube2
MkLinux DR1 PPC750 7.0 2001-04-03, Tatsuo
Ishii (<t-
7.1 needs OS
update?
NetBSD Alpha 7.2 2001-11-20,
Thomas Thai
1.5W
NetBSD m68k 7.0 2000-04-10, Henry
B. Hotz
Mac 8xx
NetBSD MIPS 7.2.1 2002-06-13,
Warwick Hunter
1.5.3
NetBSD PPC 7.2 2001-11-28, Bill
Studenmund
1.5
NetBSD Sparc 7.2 2001-12-03,
Matthew Green
32- and 64-bit
builds
NetBSD VAX 7.1 2001-03-30, Tom I.
Helbekkmo
1.5
NeXTSTEP x86 6.x 1998-03-01, David
Wetzel
bit rot suspected
QNX 4 RTOS x86 7.2 2001-12-10, Bernd
Tegge
(<tegge@repas-
aeg.de>)
needs updates to
semaphore code;
see also
doc/FAQ_QNX4
16
Chapter 1. Installation Instructions
OS Processor Version Reported Remarks
QNX RTOS v6 x86 7.2 2001-11-20, Igor
Kovalenko
patches available in
archives, but too
late for 7.2
SunOS 4 Sparc 7.2 2001-12-04, Tatsuo
Ishii (<t-
System V R4 m88k 6.2.1 1998-03-01, Doug
Winterburn
needs new TAS
spinlock code
System V R4 MIPS 6.4 1998-10-28, Frank
Ridderbusch
no recent reports
Ultrix MIPS 7.1 2001-03-26 TAS spinlock code
not detected
Ultrix VAX 6.x 1998-03-01
17
Chapter 2. Installation on Windows
Although PostgreSQL is written for Unix-like operating systems, the C client library (libpq) and the
interactive terminal (psql) can be compiled natively under Windows. The makefiles included in the source
distribution are written for Microsoft Visual C++ and will probably not work with other systems. It should
be possible to compile the libraries manually in other cases.
Tip: If you are using Windows 98 or newer you can build and use all of PostgreSQL “the Unix way” if
you install the Cygwin toolkit first. In that case see Chapter 1.
To build everything that you can on Windows, change into the src directory and type the command
nmake /f win32.mak
This assumes that you have Visual C++ in your path.
The following files will be built:
interfaces\libpq\Release\libpq.dll
The dynamically linkable frontend library
interfaces\libpq\Release\libpqdll.lib
Import library to link your program to libpq.dll
interfaces\libpq\Release\libpq.lib
Static library version of the frontend library
bin\psql\Release\psql.exe
The PostgreSQL interactive terminal
The only file that really needs to be installed is the libpq.dll library. This file should in most cases be
placed in the WINNT\SYSTEM32 directory (or in WINDOWS\SYSTEM on a Windows 95/98/ME system). If
this file is installed using a setup program, it should be installed with version checking using the VER-
SIONINFO resource included in the file, to ensure that a newer version of the library is not overwritten.
If you plan to do development using libpq on this machine, you will have to add the src\include and
src\interfaces\libpq subdirectories of the source tree to the include path in your compilers settings.
To use the libraries, you must add the libpqdll.lib file to your project. (In Visual C++, just right-click
on the project and choose to add it.)
18
Chapter 3. Server Run-time Environment
This chapter discusses how to set up and run the database server and the interactions with the operating
system.
3.1. The PostgreSQL User Account
As with any other server daemon that is connected to outside world, it is advisable to run PostgreSQL
under a separate user account. This user account should only own the data that is managed by the server,
and should not be shared with other daemons. (For example, using the user “nobody” is a bad idea.) It is
not advisable to install executables owned by this user because compromised systems could then modify
their own binaries.
To add a Unix user account to your system, look for a command useradd or adduser. The user name
postgres is often used but is by no means required.
3.2. Creating a Database Cluster
Before you can do anything, you must initialize a database storage area on disk. We call this a database
cluster. (SQL uses the term catalog cluster instead.) A database cluster is a collection of databases is
accessible by a single instance of a running database server. After initialization, a database cluster will
contain a database named template1. As the name suggests, this will be used as a template for subse-
quently created databases; it should not be used for actual work. (See Chapter 5 for information about
creating databases.)
In file system terms, a database cluster will be a single directory under which all data will be stored. We call
this the data directory or data area. It is completely up to you where you choose to store your data. There
is no default, although locations such as /usr/local/pgsql/data or /var/lib/pgsql/data are
popular. To initialize a database cluster, use the command initdb, which is installed with PostgreSQL.
The desired file system location of your database system is indicated by the -D option, for example
$ initdb -D /usr/local/pgsql/data
Note that you must execute this command while logged into the PostgreSQL user account, which is
described in the previous section.
Tip: As an alternative to the -D option, you can set the environment variable PGDATA.
initdb will attempt to create the directory you specify if it does not already exist. It is likely that it will
not have the permission to do so (if you followed our advice and created an unprivileged account). In that
case you should create the directory yourself (as root) and change the owner to be the PostgreSQL user.
Here is how this might be done:
root# mkdir /usr/local/pgsql/data
root# chown postgres /usr/local/pgsql/data
root# su postgres
postgres$ initdb -D /usr/local/pgsql/data
19
Chapter 3. Server Run-time Environment
initdb will refuse to run if the data directory looks like it it has already been initialized.
Because the data directory contains all the data stored in the database, it is essential that it be secured from
unauthorized access. initdb therefore revokes access permissions from everyone but the PostgreSQL
user.
However, while the directory contents are secure, the default client authentication setup allows any local
user to connect to the database and even become the database superuser. If you don’t trust other local users,
we recommend you use initdb’s -W or --pwprompt option to assign a password to the database supe-
ruser. After initdb, modify the pg_hba.conf file to use md5 or password instead of trust authenti-
cation before you start the server for the first time. (Other, approaches include using ident authentication
or file system permissions to restrict connections. See Chapter 6 for more information.)
initdb also initializes the default locale for the database cluster. Normally, it will just take the locale
settings in the environment and apply them to the initialized database. It is possible to specify a different
locale for the database; more information about that can be found in Section 7.1. One surprise you might
encounter while running initdb is a notice similar to this:
The database cluster will be initialized with locale de_DE.
This locale setting will prevent the use of indexes for pattern matching
operations. If that is a concern, rerun initdb with the collation order
set to "C". For more information see the Administrator’s Guide.
This is intended to warn you that the currently selected locale will cause indexes to be sorted in an order
that prevents them from being used for LIKE and regular-expression searches. If you need good perfor-
mance in such searches, you should set your current locale to C and re-run initdb, e.g., by running
initdb --lc-collate=C. The sort order used within a particular database cluster is set by initdb
and cannot be changed later, short of dumping all data, rerunning initdb, and reloading the data. So it’s
important to make this choice correctly the first time.
3.3. Starting the Database Server
Before anyone can access the database, you must start the database server. The database server is called
postmaster. The postmaster must know where to find the data it is supposed to use. This is done with the
-D option. Thus, the simplest way to start the server is:
$ postmaster -D /usr/local/pgsql/data
which will leave the server running in the foreground. This must be done while logged into the PostgreSQL
user account. Without -D, the server will try to use the data directory in the environment variable PGDATA.
If neither of these succeed, it will fail.
To start the postmaster in the background, use the usual shell syntax:
$ postmaster -D /usr/local/pgsql/data > logfile 2>&1 &
It is an important to store the server’s stdout and stderr output somewhere, as shown above. It will help
for auditing purposes and to diagnose problems. (See Section 8.4 for a more thorough discussion of log
file handling.)
20
Chapter 3. Server Run-time Environment
The postmaster also takes a number of other command line options. For more information, see the refer-
ence page and Section 3.4 below. In particular, in order for the server to accept TCP/IP connections (rather
than just Unix domain socket ones), you must specify the -i option.
This shell syntax can get tedious quickly. Therefore the shell script wrapper pg_ctl is provided to simplify
some tasks. For example:
pg_ctl start -l logfile
will start the server in the background and put the output into the named log file. The -D option has the
same meaning here as in the postmaster. pg_ctl is also capable of stopping the server.
Normally, you will want to start the database server when the computer boots. Autostart scripts are oper-
ating system-specific. There are a few distributed with PostgreSQL in the /contrib/start-scripts
directory. This may require root privileges.
Different systems have different conventions for starting up daemons at boot time. Many systems have
a file /etc/rc.local or /etc/rc.d/rc.local. Others use rc.d directories. Whatever you do, the
server must be run by the PostgreSQL user account and not by root or any other user. Therefore you
probably should form your commands using su -c ’...’ postgres. For example:
su -c ’pg_ctl start -D /usr/local/pgsql/data -l serverlog’ postgres
Here are a few more operating system specific suggestions. (Always replace these with the proper instal-
lation directory and the user name.)
• For FreeBSD, look at the file contrib/start-scripts/freebsd in the PostgreSQL source distri-
bution.
• On OpenBSD, add the following lines to the file /etc/rc.local:
if [ -x /usr/local/pgsql/bin/pg_ctl -a -x /usr/local/pgsql/bin/postmaster ]; then
su - -c ’/usr/local/pgsql/bin/pg_ctl start -l /var/postgresql/log -s’ postgres
echo -n ’ postgresql’
fi
• On Linux systems either add
/usr/local/pgsql/bin/pg_ctl start -l logfile -D /usr/local/pgsql/data
to /etc/rc.d/rc.local or look at the file contrib/start-scripts/linux in the PostgreSQL
source distribution.
• On NetBSD, either use the FreeBSD or Linux start scripts, depending on preference.
• On Solaris, create a file called /etc/init.d/postgresql which should contain the following line:
su - postgres -c "/usr/local/pgsql/bin/pg_ctl start -l logfile -D /usr/local/pgsql/data"
Then, create a symbolic link to it in /etc/rc3.d as S99postgresql.
While the postmaster is running, its PID is in the file postmaster.pid in the data directory. This is used
to prevent multiple postmasters running in the same data directory, and can also be used for shutting down
the postmaster.
21
Chapter 3. Server Run-time Environment
3.3.1. Server Start-up Failures
There are several common reasons the postmaster might fail to start. Check the postmaster’s log file, or
start it by hand (without redirecting standard output or standard error) and see what error messages appear.
Some of the error messages are self-explanatory, but some are not, as shown below:
FATAL: StreamServerPort: bind() failed: Address already in use
Is another postmaster already running on that port?
This usually means just what it suggests: you tried to start another postmaster on the same port where
one is already running. However, if the kernel error message is not Address already in use or some
variant of that, there may be a different problem. For example, trying to start a postmaster on a reserved
port number may draw something like:
$ postmaster -i -p 666
FATAL: StreamServerPort: bind() failed: Permission denied
Is another postmaster already running on that port?
A message like:
IpcMemoryCreate: shmget(key=5440001, size=83918612, 01600) failed: Invalid ar-
gument
FATAL 1: ShmemCreate: cannot create region
probably means your kernel’s limit on the size of shared memory is smaller than the buffer area Post-
greSQL is trying to create (83918612 bytes in this example). Or it could mean that you don’t have System-
V-style shared memory support configured into your kernel at all. As a temporary workaround, you can
try starting the postmaster with a smaller-than-normal number of buffers (-B switch). You will eventually
want to reconfigure your kernel to increase the allowed shared memory size. You may see this message
when trying to start multiple postmasters on the same machine if their total space requested exceeds the
kernel limit.
An error like:
IpcSemaphoreCreate: semget(key=5440026, num=16, 01600) failed: No space left on de-
vice
does not mean you’ve run out of disk space. It means your kernel’s limit on the number of System V
semaphores is smaller than the number PostgreSQL wants to create. As above, you may be able to work
around the problem by starting the postmaster with a reduced number of allowed connections (-N switch),
but you’ll eventually want to increase the kernel limit.
If you get an “illegal system call” error, it is likely that shared memory or semaphores are not supported
in your kernel at all. In that case your only option is to reconfigure the kernel to enable these features.
Details about configuring System V IPC facilities are given in Section 3.5.1.
22
Chapter 3. Server Run-time Environment
3.3.2. Client Connection Problems
Although the error conditions possible on the client side are quite varied and application-dependent, a few
of them might be directly related to how the server was started up. Conditions other than those shown
below should be documented with the respective client application.
psql: could not connect to server: Connection refused
Is the server running on host server.joe.com and accepting
TCP/IP connections on port 5432?
This is the generic “I couldn’t find a server to talk to” failure. It looks like the above when TCP/IP
communication is attempted. A common mistake is to forget the -i option to allow the postmaster to
accept TCP/IP connections.
Alternatively, you’ll get this when attempting Unix-socket communication to a local postmaster:
psql: could not connect to server: Connection refused
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
The last line is useful in verifying that the client is trying to connect to the right place. If there is in fact
no postmaster running there, the kernel error message will typically be either Connection refused or
No such file or directory, as illustrated. (It is important to realize that Connection refused
in this context does not mean that the postmaster got your connection request and rejected it -- that case
will produce a different message, as shown in Section 6.3.) Other error messages such as Connection
timed out may indicate more fundamental problems, like lack of network connectivity.
3.4. Run-time Configuration
There are a lot of configuration parameters that affect the behavior of the database system. Here we
describe how to set them and the following subsections will discuss each in detail.
All parameter names are case-insensitive. Every parameter takes a value of one of the four types:
Boolean, integer, floating point, and string. Boolean values are ON, OFF, TRUE, FALSE, YES, NO, 1, 0
(case-insensitive) or any non-ambiguous prefix of these.
One way to set these options is to edit the file postgresql.conf in the data directory. (A default file is
installed there.) An example of what this file might look like is:
# This is a comment
log_connections = yes
syslog = 2
search_path = ’$user, public’
As you see, options are one per line. The equal sign between name and value is optional. Whitespace
is insignificant and blank lines are ignored. Hash marks (“#”) introduce comments anywhere. Parameter
values that are not simple identifiers or numbers should be single-quoted.
The configuration file is reread whenever the postmaster receives a SIGHUP signal (which is most easily
sent by means of pg_ctl reload). The postmaster also propagates this signal to all currently running
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Chapter 3. Server Run-time Environment
backend processes so that existing sessions also get the new value. Alternatively, you can send the signal
to a single backend process directly.
A second way to set these configuration parameters is to give them as a command line option to the
postmaster, such as:
postmaster -c log_connections=yes -c syslog=2
which would have the same effect as the previous example. Command-line options override any conflict-
ing settings in postgresql.conf.
Occasionally it is also useful to give a command line option to one particular backend session only. The
environment variable PGOPTIONS can be used for this purpose on the client side:
env PGOPTIONS=’-c geqo=off’ psql
(This works for any libpq-based client application, not just psql.) Note that this won’t work for options
that are fixed when the server is started, such as the port number.
Some options can be changed in individual SQL sessions with the SET command, for example:
=> SET ENABLE_SEQSCAN TO OFF;
See the SQL command language reference for details on the syntax.
Furthermore, it is possible to assign a set of option settings to a user or a database. Whenever a ses-
sion is started, the default settings for the user and database involved are loaded. The commands ALTER
DATABASE and ALTER USER, respectively, are used to configure these settings. Such per-database set-
tings override anything received from the postmaster or the configuration file, and in turn are overridden
by per-user settings.
3.4.1. pg_settings
The pg_settings virtual table allows display and update of current session run-time parameters. There
is one entry for each of the available parameters provided by SHOW ALL. But it is in a form that allows it
to be joined with other relations and have a selection criteria applied.
An UPDATE performed on pg_settings is equivalent to executing the SET command on that named
parameter. The change only affects the value used by the current session. If an UPDATE is issued within
a transaction that is later aborted, the effects of the UPDATE command disappear when the transaction is
rolled back. Once the surrounding transaction is committed, the effects will persist until the end of the
session, unless overridden by another UPDATE or SET.
Table 3-1. pg_settings Columns
Name Type Description
name text The name of a current session
run-time parameter
setting text The value of a current session
run-time parameter
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Chapter 3. Server Run-time Environment
3.4.2. Planner and Optimizer Tuning
CPU_INDEX_TUPLE_COST (floating point)
Sets the query optimizer’s estimate of the cost of processing each index tuple during an index scan.
This is measured as a fraction of the cost of a sequential page fetch.
CPU_OPERATOR_COST (floating point)
Sets the optimizer’s estimate of the cost of processing each operator in a WHERE clause. This is
measured as a fraction of the cost of a sequential page fetch.
CPU_TUPLE_COST (floating point)
Sets the query optimizer’s estimate of the cost of processing each tuple during a query. This is mea-
sured as a fraction of the cost of a sequential page fetch.
DEFAULT_STATISTICS_TARGET (integer)
Sets the default statistics target for table columns that have not had a column-specific target set via
ALTER TABLE SET STATISTICS. Larger values increase the time needed to do ANALYZE, but may
improve the quality of the planner’s estimates.
EFFECTIVE_CACHE_SIZE (floating point)
Sets the optimizer’s assumption about the effective size of the disk cache (that is, the portion of the
kernel’s disk cache that will be used for PostgreSQL data files). This is measured in disk pages,
which are normally 8 kB each.
ENABLE_HASHJOIN (boolean)
Enables or disables the query planner’s use of hash-join plan types. The default is on. This is used
for debugging the query planner.
ENABLE_INDEXSCAN (boolean)
Enables or disables the query planner’s use of index-scan plan types. The default is on. This is used
to debugging the query planner.
ENABLE_MERGEJOIN (boolean)
Enables or disables the query planner’s use of merge-join plan types. The default is on. This is used
for debugging the query planner.
ENABLE_NESTLOOP (boolean)
Enables or disables the query planner’s use of nested-loop join plans. It’s not possible to suppress
nested-loop joins entirely, but turning this variable off discourages the planner from using one if there
are other methods available. The default is on. This is used for debugging the query planner.
ENABLE_SEQSCAN (boolean)
Enables or disables the query planner’s use of sequential scan plan types. It’s not possible to suppress
sequential scans entirely, but turning this variable off discourages the planner from using one if there
are other methods available. The default is on. This is used for debugging the query planner.
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Chapter 3. Server Run-time Environment
ENABLE_SORT (boolean)
Enables or disables the query planner’s use of explicit sort steps. It’s not possible to suppress explicit
sorts entirely, but turning this variable off discourages the planner from using one if there are other
methods available. The default is on. This is used for debugging the query planner.
ENABLE_TIDSCAN (boolean)
Enables or disables the query planner’s use of TID scan plan types. The default is on. This is used
for debugging the query planner.
GEQO (boolean)
Enables or disables genetic query optimization, which is an algorithm that attempts to do query plan-
ning without exhaustive searching. This is on by default. See also the various other GEQO_ settings.
GEQO_EFFORT (integer)
GEQO_GENERATIONS (integer)
GEQO_POOL_SIZE (integer)
GEQO_RANDOM_SEED (integer)
GEQO_SELECTION_BIAS (floating point)
Various tuning parameters for the genetic query optimization algorithm: The pool size is the number
of individuals in one population. Valid values are between 128 and 1024. If it is set to 0 (the default)
a pool size of 2^(QS+1), where QS is the number of FROM items in the query, is taken. The effort
is used to calculate a default for generations. Valid values are between 1 and 80, 40 being the de-
fault. Generations specifies the number of iterations in the algorithm. The number must be a positive
integer. If 0 is specified then Effort * Log2(PoolSize) is used. The run time of the algorithm
is roughly proportional to the sum of pool size and generations. The selection bias is the selective
pressure within the population. Values can be from 1.50 to 2.00; the latter is the default. The random
seed can be set to get reproducible results from the algorithm. If it is set to -1 then the algorithm
behaves non-deterministically.
GEQO_THRESHOLD (integer)
Use genetic query optimization to plan queries with at least this many FROM items involved. (Note
that a JOIN construct counts as only one FROM item.) The default is 11. For simpler queries it is
usually best to use the deterministic, exhaustive planner. This parameter also controls how hard the
optimizer will try to merge subquery FROM clauses into the upper query.
RANDOM_PAGE_COST (floating point)
Sets the query optimizer’s estimate of the cost of a nonsequentially fetched disk page. This is mea-
sured as a multiple of the cost of a sequential page fetch.
Note: Unfortunately, there is no well-defined method for determining ideal values for the family of
“COST” variables that were just described. You are encouraged to experiment and share your findings.
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Chapter 3. Server Run-time Environment
3.4.3. Logging and Debugging
SERVER_MIN_MESSAGES (string)
This controls how much message detail is written to the server logs. Valid values are DEBUG5, DE-
BUG4, DEBUG3, DEBUG2, DEBUG1, INFO, NOTICE, WARNING, ERROR, LOG, FATAL, and PANIC. Later
values send less detail to the logs. The default is NOTICE. Note that LOG has a different precedence
here than in CLIENT_MIN_MESSAGES.
Here is a summary of the various message types:
DEBUG[1-5]
Provides information for use by developers.
INFO
Provides information implicitly requested by the user, e.g., during VACUUM VERBOSE.
NOTICE
Provides information that may be helpful to users, e.g., truncation of long identifiers and index
creation as part of primary keys.
WARNING
Provides warnings to the user, e.g., COMMIT outside a transaction.
ERROR
Reports the error that caused a transaction to abort.
LOG
Reports information of interest to administrators, e.g., checkpoint activity.
FATAL
Reports why a backend session terminated.
PANIC
Reports why all backend sessions restarted.
CLIENT_MIN_MESSAGES (string)
This controls how much message detail is written to the client. Valid values are DEBUG5, DEBUG4,
DEBUG3, DEBUG2, DEBUG1, LOG, NOTICE, WARNING, and ERROR. Later values send less informa-
tion to the client. The default is NOTICE. Note that LOG has a different precedence here than in
SERVER_MIN_MESSAGES. Also see that section for an explanation of the various values.
DEBUG_ASSERTIONS (boolean)
Turns on various assertion checks. This is a debugging aid. If you are experiencing strange problems
or crashes you might want to turn this on, as it might expose programming mistakes. To use this op-
tion, the macro USE_ASSERT_CHECKING must be defined when PostgreSQL is built (accomplished
by the configure option --enable-cassert). Note that DEBUG_ASSERTIONS defaults to on if
PostgreSQL has been built with assertions enabled.
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Chapter 3. Server Run-time Environment
DEBUG_PRINT_PARSE (boolean)
DEBUG_PRINT_REWRITTEN (boolean)
DEBUG_PRINT_PLAN (boolean)
DEBUG_PRETTY_PRINT (boolean)
These flags enable various debugging output to be sent to the server log. For each executed query,
print either the query text, the resulting parse tree, the query rewriter output, or the execution plan.
DEBUG_PRETTY_PRINT indents these displays to produce a more readable but much longer output
format.
EXPLAIN_PRETTY_PRINT (boolean)
Determines whether EXPLAIN VERBOSE uses the indented or non-indented format for displaying
detailed query-tree dumps.
HOSTNAME_LOOKUP (boolean)
By default, connection logs only show the IP address of the connecting host. If you want it to show
the host name you can turn this on, but depending on your host name resolution setup it might impose
a non-negligible performance penalty. This option can only be set at server start.
LOG_CONNECTIONS (boolean)
This outputs a line to the server logs detailing each successful connection. This is off by default,
although it is probably very useful. This option can only be set at server start or in the post-
gresql.conf configuration file.
LOG_DURATION (boolean)
Causes the duration of every completed statement to be logged. To use this option, enable
LOG_STATEMENT and LOG_PID so you can link the statement to the duration using the process ID.
LOG_MIN_ERROR_STATEMENT (string)
This controls for which message levels the SQL statement causing that message is to be recorded in
the server log. All statements causing a message of the level of the setting or higher are logged. The
default is PANIC (effectively turning this feature off). Valid values are DEBUG5, DEBUG4, DEBUG3,
DEBUG2, DEBUG1, INFO, NOTICE, WARNING, ERROR, FATAL, and PANIC. For example, if you set this
to ERROR then all SQL statements causing errors, fatal errors, or panics will be logged.
It is recommended you enable LOG_PID as well so you can more easily match the error statement
with the error message.
LOG_PID (boolean)
Prefixes each server message in the log file with the process ID of the backend process. This is useful
to sort out which messages pertain to which connection. The default is off. This parameter does not
affect messages logged via syslog, which always contain the process ID.
LOG_STATEMENT (boolean)
Causes each SQL statement to be logged.
LOG_TIMESTAMP (boolean)
Prefixes each server log message with a time stamp. The default is off.
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Chapter 3. Server Run-time Environment
SHOW_STATEMENT_STATS (boolean)
SHOW_PARSER_STATS (boolean)
SHOW_PLANNER_STATS (boolean)
SHOW_EXECUTOR_STATS (boolean)
For each query, write performance statistics of the respective module to the server log. This is a crude
profiling instrument.
SHOW_SOURCE_PORT (boolean)
Shows the outgoing port number of the connecting host in the connection log messages. You could
trace back the port number to find out what user initiated the connection. Other than that, it’s pretty
useless and therefore off by default. This option can only be set at server start.
STATS_COMMAND_STRING (boolean)
STATS_BLOCK_LEVEL (boolean)
STATS_ROW_LEVEL (boolean)
These flags determine what information backends send to the statistics collector process: current
commands, block-level activity statistics, or row-level activity statistics. All default to off. Enabling
statistics collection costs a small amount of time per query, but is invaluable for debugging and
performance tuning.
STATS_RESET_ON_SERVER_START (boolean)
If on, collected statistics are zeroed out whenever the server is restarted. If off, statistics are accumu-
lated across server restarts. The default is on. This option can only be set at server start.
STATS_START_COLLECTOR (boolean)
Controls whether the server should start the statistics-collection subprocess. This is on by default,
but may be turned off if you know you have no interest in collecting statistics. This option can only
be set at server start.
SYSLOG (integer)
PostgreSQL allows the use of syslog for logging. If this option is set to 1, messages go both to syslog
and the standard output. A setting of 2 sends output only to syslog. (Some messages will still go to
the standard output/error.) The default is 0, which means syslog is off. This option must be set at
server start.
SYSLOG_FACILITY (string)
This option determines the syslog “facility” to be used when syslog is enabled. You may choose from
LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7; the default is LOCAL0. See
also the documentation of your system’s syslog.
SYSLOG_IDENT (string)
If logging to syslog is enabled, this option determines the program name used to identify PostgreSQL
messages in syslog log messages. The default is postgres.
TRACE_NOTIFY (boolean)
Generates a great amount of debugging output for the LISTEN and NOTIFY commands.
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Chapter 3. Server Run-time Environment
3.4.4. General Operation
AUTOCOMMIT (boolean)
If set to true, PostgreSQL will automatically do a COMMIT after each successful command that is
not inside an explicit transaction block (that is, unless a BEGIN with no matching COMMIT has been
given). If set to false, PostgreSQL will commit only upon receiving an explicit COMMIT command.
This mode can also be thought of as implicitly issuing BEGIN whenever a command is received
that is not already inside a transaction block. The default is true, for compatibility with historical
PostgreSQL behavior. However, for maximum compatibility with the SQL specification, set it to
false.
Note: Even with autocommit set to false, SET, SHOW, and RESET do not start new transaction
blocks. They are run in their own transactions. Once another command is issued, a transaction
block begins and any SET, SHOW, or RESET commands are considered to be part of the transaction,
i.e., they are committed or rolled back depending on the completion status of the transaction. To
execute a SET, SHOW, or RESET command at the start of a transaction block, use BEGIN first.
Note: As of PostgreSQL 7.3, setting autocommit to false is not well-supported. This is a new
feature and is not yet handled by all client libraries and applications. Before making it the default
setting in your installation, test carefully.
AUSTRALIAN_TIMEZONES (boolean)
If set to true, CST, EST, and SAT are interpreted as Australian time zones rather than as North Amer-
ican Central/Eastern time zones and Saturday. The default is false.
AUTHENTICATION_TIMEOUT (integer)
Maximum time to complete client authentication, in seconds. If a would-be client has not completed
the authentication protocol in this much time, the server breaks the connection. This prevents hung
clients from occupying a connection indefinitely. This option can only be set at server start or in the
postgresql.conf file.
CLIENT_ENCODING (string)
Sets the client-side encoding for multibyte character sets. The default is to use the database encoding.
DATESTYLE (string)
Sets the display format for dates, as well as the rules for interpreting ambiguous input dates. The
default is ISO, US.
DB_USER_NAMESPACE (boolean)
This allows per-database user names. It is off by default.
If this is on, create users as username@dbname. When username is passed by a connecting client,
@ and the database name is appended to the user name and that database-specific user name is looked
up by the server. Note that when you create users with names containing @ within the SQL environ-
ment, you will need to quote the user name.
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Chapter 3. Server Run-time Environment
With this option enabled, you can still create ordinary global users. Simply append @ when specifying
the user name in the client. The @ will be stripped off before the user name is looked up by the server.
Note: This feature is intended as a temporary measure until a complete solution is found. At that
time, this option will be removed.
DEADLOCK_TIMEOUT (integer)
This is the amount of time, in milliseconds, to wait on a lock before checking to see if there is
a deadlock condition. The check for deadlock is relatively slow, so the server doesn’t run it every
time it waits for a lock. We (optimistically?) assume that deadlocks are not common in production
applications and just wait on the lock for a while before starting check for a deadlock. Increasing
this value reduces the amount of time wasted in needless deadlock checks, but slows down reporting
of real deadlock errors. The default is 1000 (i.e., one second), which is probably about the smallest
value you would want in practice. On a heavily loaded server you might want to raise it. Ideally the
setting should exceed your typical transaction time, so as to improve the odds that the lock will be
released before the waiter decides to check for deadlock. This option can only be set at server start.
DEFAULT_TRANSACTION_ISOLATION (string)
Each SQL transaction has an isolation level, which can be either “read committed” or “serializable”.
This parameter controls the default isolation level of each new transaction. The default is “read
committed”.
Consult the PostgreSQL User’s Guide and the command SET TRANSACTION for more information.
DYNAMIC_LIBRARY_PATH (string)
If a dynamically loadable module needs to be opened and the specified name does not have a directory
component (i.e. the name does not contain a slash), the system will search this path for the specified
file. (The name that is used is the name specified in the CREATE FUNCTION or LOAD command.)
The value for dynamic_library_path has to be a colon-separated list of absolute directory names.
If a directory name starts with the special value $libdir, the compiled-in PostgreSQL package
library directory is substituted. This where the modules provided by the PostgreSQL distribution are
installed. (Use pg_config --pkglibdir to print the name of this directory.) For example:
dynamic_library_path = ’/usr/local/lib/postgresql:/home/my_project/lib:$libdir’
The default value for this parameter is ’$libdir’. If the value is set to an empty string, the automatic
path search is turned off.
This parameter can be changed at run time by superusers, but a setting done that way will only persist
until the end of the client connection, so this method should be reserved for development purposes.
The recommended way to set this parameter is in the postgresql.conf configuration file.
KRB_SERVER_KEYFILE (string)
Sets the location of the Kerberos server key file. See Section 6.2.3 for details.
FSYNC (boolean)
If this option is on, the PostgreSQL backend will use the fsync() system call in several places to
make sure that updates are physically written to disk. This insures that a database installation will
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Chapter 3. Server Run-time Environment
recover to a consistent state after an operating system or hardware crash. (Crashes of the database
server itself are not related to this.)
However, this operation does slow down PostgreSQL because at transaction commit it has wait for
the operating system to flush the write-ahead log. Without fsync, the operating system is allowed to
do its best in buffering, sorting, and delaying writes, which can considerably increase performance.
However, if the system crashes, the results of the last few committed transactions may be lost in part
or whole. In the worst case, unrecoverable data corruption may occur.
For the above reasons, some administrators always leave it off, some turn it off only for bulk loads,
where there is a clear restart point if something goes wrong, and some leave it on just to be on the safe
side. Because it is always safe, the default is on. If you trust your operating system, your hardware,
and your utility company (or better your UPS), you might want to disable fsync.
It should be noted that the performance penalty of doing fsyncs is considerably less in PostgreSQL
version 7.1 and later. If you previously suppressed fsyncs for performance reasons, you may wish
to reconsider your choice.
This option can only be set at server start or in the postgresql.conf file.
LC_MESSAGES (string)
Sets the language in which messages are displayed. Acceptable values are system-dependent; see
Section 7.1 for more information. If this variable is set to the empty string (which is the default) then
the value is inherited from the execution environment of the server in a system-dependent way.
On some systems, this locale category does not exist. Setting this variable will still work, but there
will be no effect. Also, there is a chance that no translated messages for the desired language exist.
In that case you will continue to see the English messages.
LC_MONETARY (string)
Sets the locale to use for formatting monetary amounts, for example with the to_char() family
of functions. Acceptable values are system-dependent; see Section 7.1 for more information. If this
variable is set to the empty string (which is the default) then the value is inherited from the execution
environment of the server in a system-dependent way.
LC_NUMERIC (string)
Sets the locale to use for formatting numbers, for example with the to_char() family of functions.
Acceptable values are system-dependent; see Section 7.1 for more information. If this variable is set
to the empty string (which is the default) then the value is inherited from the execution environment
of the server in a system-dependent way.
LC_TIME (string)
Sets the locale to use for formatting date and time values. (Currently, this setting does nothing, but it
may in the future.) Acceptable values are system-dependent; see Section 7.1 for more information.
If this variable is set to the empty string (which is the default) then the value is inherited from the
execution environment of the server in a system-dependent way.
MAX_CONNECTIONS (integer)
Determines the maximum number of concurrent connections to the database server. The default is 32
(unless altered while building the server). This parameter can only be set at server start.
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Chapter 3. Server Run-time Environment
MAX_EXPR_DEPTH (integer)
Sets the maximum expression nesting depth of the parser. The default value is high enough for any
normal query, but you can raise it if needed. (But if you raise it too high, you run the risk of backend
crashes due to stack overflow.)
MAX_FILES_PER_PROCESS (integer)
Sets the maximum number of simultaneously open files in each server subprocess. The default
is 1000. The limit actually used by the code is the smaller of this setting and the result of
sysconf(_SC_OPEN_MAX). Therefore, on systems where sysconf returns a reasonable limit,
you don’t need to worry about this setting. But on some platforms (notably, most BSD systems),
sysconf returns a value that is much larger than the system can really support when a large
number of processes all try to open that many files. If you find yourself seeing “Too many
open files” failures, try reducing this setting. This option can only be set at server start or in
the postgresql.conf configuration file; if changed in the configuration file, it only affects
subsequently-started server subprocesses.
MAX_FSM_RELATIONS (integer)
Sets the maximum number of relations (tables) for which free space will be tracked in the shared
free-space map. The default is 1000. This option can only be set at server start.
MAX_FSM_PAGES (integer)
Sets the maximum number of disk pages for which free space will be tracked in the shared free-space
map. The default is 10000. This option can only be set at server start.
MAX_LOCKS_PER_TRANSACTION (integer)
The shared lock table is sized on the assumption that at most max_locks_per_transaction *
max_connections distinct objects will need to be locked at any one time. The default, 64, which
has historically proven sufficient, but you might need to raise this value if you have clients that touch
many different tables in a single transaction. This option can only be set at server start.
PASSWORD_ENCRYPTION (boolean)
When a password is specified in CREATE USER or ALTER USER without writing either ENCRYPTED
or UNENCRYPTED, this flag determines whether the password is to be encrypted. The default is on
(encrypt the password).
PORT (integer)
The TCP port the server listens on; 5432 by default. This option can only be set at server start.
SEARCH_PATH (string)
This variable specifies the order in which schemas are searched when an object (table, data type,
function, etc.) is referenced by a simple name with no schema component. When there are objects
of identical names in different schemas, the one found first in the search path is used. An object that
is not in any of the schemas in the search path can only be referenced by specifying its containing
schema with a qualified (dotted) name.
The value for search_path has to be a comma-separated list of schema names. If one of the list
items is the special value $user, then the schema having the same name as the SESSION_USER is
substituted, if there is such a schema. (If not, $user is ignored.)
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Chapter 3. Server Run-time Environment
The system catalog schema, pg_catalog, is always searched, whether it is mentioned in the path
or not. If it is mentioned in the path then it will be searched in the specified order. If pg_catalog is
not in the path then it will be searched before searching any of the path items. It should also be noted
that the temporary-table schema, pg_temp_nnn, is implicitly searched before any of these.
When objects are created without specifying a particular target schema, they will be placed in the
first schema listed in the search path. An error is reported if the search path is empty.
The default value for this parameter is ’$user, public’ (where the second part will be ignored
if there is no schema named public). This supports shared use of a database (where no users have
private schemas, and all share use of public), private per-user schemas, and combinations of these.
Other effects can be obtained by altering the default search path setting, either globally or per-user.
The current effective value of the search path can be examined via the SQL function
current_schemas(). This is not quite the same as examining the value of search_path, since
current_schemas() shows how the requests appearing in search_path were resolved.
For more information on schema handling, see the PostgreSQL User’s Guide.
STATEMENT_TIMEOUT (integer)
Aborts any statement that takes over the specified number of milliseconds. A value of zero turns off
the timer.
SHARED_BUFFERS (integer)
Sets the number of shared memory buffers used by the database server. The default is 64. Each
buffer is typically 8192 bytes. This must be greater than 16, as well as at least twice the value of
MAX_CONNECTIONS; however, a higher value can often improve performance on modern machines.
Values of at least a few thousand are recommended for production installations. This option can only
be set at server start.
Increasing this parameter may cause PostgreSQL to request more System V shared memory than
your operating system’s default configuration allows. See Section 3.5.1 for information on how to
adjust these parameters, if necessary.
SILENT_MODE (bool)
Runs the server silently. If this option is set, the server will automatically run in background and any
controlling ttys are disassociated, thus no messages are written to standard output or standard error
(same effect as postmaster’s -S option). Unless some logging system such as syslog is enabled,
using this option is discouraged since it makes it impossible to see error messages.
SORT_MEM (integer)
Specifies the amount of memory to be used by internal sorts and hashes before switching to temporary
disk files. The value is specified in kilobytes, and defaults to 1024 kilobytes (1 MB). Note that for
a complex query, several sorts might be running in parallel, and each one will be allowed to use
as much memory as this value specifies before it starts to put data into temporary files. Also, each
running backend could be doing one or more sorts simultaneously, so the total memory used could be
many times the value of SORT_MEM. Sorts are used by ORDER BY, merge joins, and CREATE INDEX.
SQL_INHERITANCE (bool)
This controls the inheritance semantics, in particular whether subtables are included by various com-
mands by default. They were not included in versions prior to 7.1. If you need the old behavior you
can set this variable to off, but in the long run you are encouraged to change your applications to use
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Chapter 3. Server Run-time Environment
the ONLY keyword to exclude subtables. See the SQL language reference and the PostgreSQL User’s
Guide for more information about inheritance.
SSL (boolean)
Enables SSL connections. Please read Section 3.7 before using this. The default is off.
SUPERUSER_RESERVED_CONNECTIONS (integer)
Determines the number of “connection slots” that are reserved for connections by PostgreSQL
superusers. At most max_connections connections can ever be active simultaneously.
Whenever the number of active concurrent connections is at least max_connections minus
superuser_reserved_connections, new connections will be accepted only from superuser
accounts.
The default value is 2. The value must be less than the value of max_connections. This parameter
can only be set at server start.
TCPIP_SOCKET (boolean)
If this is true, then the server will accept TCP/IP connections. Otherwise only local Unix domain
socket connections are accepted. It is off by default. This option can only be set at server start.
TIMEZONE (string)
Sets the time zone for displaying and interpreting timestamps. The default is to use whatever the
system environment specifies as the time zone.
TRANSFORM_NULL_EQUALS (boolean)
When turned on, expressions of the form expr = NULL (or NULL = expr) are treated as expr IS
NULL, that is, they return true if expr evaluates to the null value, and false otherwise. The correct
behavior of expr = NULL is to always return null (unknown). Therefore this option defaults to off.
However, filtered forms in Microsoft Access generate queries that appear to use expr = NULL to
test for null values, so if you use that interface to access the database you might want to turn this
option on. Since expressions of the form expr = NULL always return the null value (using the
correct interpretation) they are not very useful and do not appear often in normal applications, so
this option does little harm in practice. But new users are frequently confused about the semantics of
expressions involving null values, so this option is not on by default.
Note that this option only affects the literal = operator, not other comparison operators or other
expressions that are computationally equivalent to some expression involving the equals operator
(such as IN). Thus, this option is not a general fix for bad programming.
Refer to the PostgreSQL User’s Guide for related information.
UNIX_SOCKET_DIRECTORY (string)
Specifies the directory of the Unix-domain socket on which the server is to listen for connections
from client applications. The default is normally /tmp, but can be changed at build time.
UNIX_SOCKET_GROUP (string)
Sets the group owner of the Unix domain socket. (The owning user of the socket is always the user
that starts the server.) In combination with the option UNIX_SOCKET_PERMISSIONS this can be used
as an additional access control mechanism for this socket type. By default this is the empty string,
which uses the default group for the current user. This option can only be set at server start.
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Chapter 3. Server Run-time Environment
UNIX_SOCKET_PERMISSIONS (integer)
Sets the access permissions of the Unix domain socket. Unix domain sockets use the usual Unix file
system permission set. The option value is expected to be an numeric mode specification in the form
accepted by the chmod and umask system calls. (To use the customary octal format the number must
start with a 0 (zero).)
The default permissions are 0777, meaning anyone can connect. Reasonable alternatives are 0770
(only user and group, see also under UNIX_SOCKET_GROUP) and 0700 (only user). (Note that ac-
tually for a Unix domain socket, only write permission matters and there is no point in setting or
revoking read or execute permissions.)
This access control mechanism is independent of the one described in Chapter 6.
This option can only be set at server start.
VACUUM_MEM (integer)
Specifies the maximum amount of memory to be used by VACUUM to keep track of to-be-reclaimed tu-
ples. The value is specified in kilobytes, and defaults to 8192 kilobytes. Larger settings may improve
the speed of vacuuming large tables that have many deleted tuples.
VIRTUAL_HOST (string)
Specifies the TCP/IP host name or address on which the postmaster is to listen for connections from
client applications. Defaults to listening on all configured addresses (including localhost).
3.4.5. WAL
See also Section 12.3 for details on WAL tuning.
CHECKPOINT_SEGMENTS (integer)
Maximum distance between automatic WAL checkpoints, in log file segments (each segment is nor-
mally 16 megabytes). This option can only be set at server start or in the postgresql.conf file.
CHECKPOINT_TIMEOUT (integer)
Maximum time between automatic WAL checkpoints, in seconds. This option can only be set at
server start or in the postgresql.conf file.
COMMIT_DELAY (integer)
Time delay between writing a commit record to the WAL buffer and flushing the buffer out to disk, in
microseconds. A nonzero delay allows multiple transactions to be committed with only one fsync
system call, if system load is high enough additional transactions may become ready to commit
within the given interval. But the delay is just wasted if no other transactions become ready to com-
mit. Therefore, the delay is only performed if at least COMMIT_SIBLINGS other transactions are
active at the instant that a backend process has written its commit record.
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Chapter 3. Server Run-time Environment
COMMIT_SIBLINGS (integer)
Minimum number of concurrent open transactions to require before performing the COMMIT_DELAY
delay. A larger value makes it more probable that at least one other transaction will become ready to
commit during the delay interval.
WAL_BUFFERS (integer)
Number of disk-page buffers in shared memory for WAL logging. The default is 4. This option can
only be set at server start.
WAL_DEBUG (integer)
If nonzero, turn on WAL-related debugging output on standard error.
WAL_SYNC_METHOD (string)
Method used for forcing WAL updates out to disk. Possible values are FSYNC (call fsync() at
each commit), FDATASYNC (call fdatasync() at each commit), OPEN_SYNC (write WAL files with
open() option O_SYNC), or OPEN_DATASYNC (write WAL files with open() option O_DSYNC). Not
all of these choices are available on all platforms. This option can only be set at server start or in the
postgresql.conf file.
3.4.6. Short Options
For convenience there are also single letter option switches available for many parameters. They are
described in Table 3-2.
Table 3-2. Short option key
Short option Equivalent
-B x shared_buffers = x
-d x server_min_messages = DEBUGx
-F fsync = off
-h x virtual_host = x
-i tcpip_socket = on
-k x unix_socket_directory = x
-l ssl = on
-N x max_connections = x
-p x port = x
-fi, -fh, -fm, -fn, -fs, -fta enable_indexscan=off,
enable_hashjoin=off,
enable_mergejoin=off,
enable_nestloop=off,
enable_seqscan=off, enable_tidscan=off
-sa show_statement_stats = on
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Chapter 3. Server Run-time Environment
Short option Equivalent
-S xa sort_mem = x
-tpa, -tpl, -tea show_parser_stats=on,
show_planner_stats=on,
show_executor_stats=on
Notes:
a. For historical reasons, these options must be passed to the individual backend process via the
-o postmaster option, for example,
$ postmaster -o ’-S 1024 -s’
or via PGOPTIONS from the client side, as explained above.
3.5. Managing Kernel Resources
A large PostgreSQL installation can quickly exhaust various operating system resource limits. (On some
systems, the factory defaults are so low that you don’t even need a really “large” installation.) If you have
encountered this kind of problem, keep reading.
3.5.1. Shared Memory and Semaphores
Shared memory and semaphores are collectively referred to as “System V IPC” (together with message
queues, which are not relevant for PostgreSQL). Almost all modern operating systems provide these
features, but not all of them have them turned on or sufficiently sized by default, especially systems with
BSD heritage. (For the QNX and BeOS ports, PostgreSQL provides its own replacement implementation
of these facilities.)
The complete lack of these facilities is usually manifested by an Illegal system call error upon postmaster
start. In that case there’s nothing left to do but to reconfigure your kernel -- PostgreSQL won’t work
without them.
When PostgreSQL exceeds one of the various hard IPC limits, the postmaster will refuse to start and
should leave an instructive error message describing the problem encountered and what to do about it.
(See also Section 3.3.1.) The relevant kernel parameters are named consistently across different systems;
Table 3-3 gives an overview. The methods to set them, however, vary. Suggestions for some platforms are
given below. Be warned that it is often necessary to reboot your machine, and possibly even recompile the
kernel, to change these settings.
Table 3-3. System V IPC parameters
Name Description Reasonable values
SHMMAX Maximum size of shared memory
segment (bytes)
250kB + 8.2 kB *
shared_buffers + 14.2 kB *
max_connections or infinity
SHMMIN Minimum size of shared memory
segment (bytes)
1
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Chapter 3. Server Run-time Environment
Name Description Reasonable values
SHMALL Total amount of shared memory
available (bytes or pages)
if bytes, same as SHMMAX; if
pages,
ceil(SHMMAX/PAGE_SIZE)
SHMSEG Maximum number of shared
memory segments per process
only 1 segment is needed, but the
default is much higher
SHMMNI Maximum number of shared
memory segments system-wide
like SHMSEG plus room for other
applications
SEMMNI Maximum number of semaphore
identifiers (i.e., sets)
>= ceil(max_connections /
16)
SEMMNS Maximum number of semaphores
system-wide
ceil(max_connections /
16) * 17 + room for other
applications
SEMMSL Maximum number of semaphores
per set
>= 17
SEMMAP Number of entries in semaphore
map
see text
SEMVMX Maximum value of semaphore >= 255 (The default is often
32767, don’t change unless asked
to.)
The most important shared memory parameter is SHMMAX, the maximum size, in bytes, of a shared memory
segment. If you get an error message from shmget like Invalid argument, it is possible that this limit has
been exceeded. The size of the required shared memory segment varies both with the number of requested
buffers (-B option) and the number of allowed connections (-N option), although the former is the most
significant. (You can, as a temporary solution, lower these settings to eliminate the failure.) As a rough
approximation, you can estimate the required segment size by multiplying the number of buffers and the
block size (8 kB by default) plus ample overhead (at least half a megabyte). Any error message you might
get will contain the size of the failed allocation request.
Less likely to cause problems is the minimum size for shared memory segments (SHMMIN), which should
be at most approximately 256 kB for PostgreSQL (it is usually just 1). The maximum number of segments
system-wide (SHMMNI) or per-process (SHMSEG) should not cause a problem unless your system has them
set to zero. Some systems also have a limit on the total amount of shared memory in the system; see the
platform-specific instructions below.
PostgreSQL uses one semaphore per allowed connection (-N option), in sets of 16. Each such set will
also contain a 17th semaphore which contains a “magic number”, to detect collision with semaphore
sets used by other applications. The maximum number of semaphores in the system is set by SEMMNS,
which consequently must be at least as high as the connection setting plus one extra for each 16 al-
lowed connections (see the formula in Table 3-3). The parameter SEMMNI determines the limit on the
number of semaphore sets that can exist on the system at one time. Hence this parameter must be at
least ceil(max_connections / 16). Lowering the number of allowed connections is a temporary
workaround for failures, which are usually confusingly worded “No space left on device”, from the func-
tion semget().
In some cases it might also be necessary to increase SEMMAP to be at least on the order of SEMMNS. This
parameter defines the size of the semaphore resource map, in which each contiguous block of available
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Chapter 3. Server Run-time Environment
semaphores needs an entry. When a semaphore set is freed it is either added to an existing entry that
is adjacent to the freed block or it is registered under a new map entry. If the map is full, the freed
semaphores get lost (until reboot). Fragmentation of the semaphore space could over time lead to fewer
available semaphores than there should be.
The SEMMSL parameter, which determines how many semaphores can be in a set, must be at least 17 for
PostgreSQL.
Various other settings related to “semaphore undo”, such as SEMMNU and SEMUME, are not of concern for
PostgreSQL.
BSD/OS
Shared Memory. By default, only 4 MB of shared memory is supported. Keep in mind that shared
memory is not pageable; it is locked in RAM. To increase the number of shared buffers supported
by the postmaster, add the following to your kernel configuration file. A SHMALL value of 1024
represents 4 MB of shared memory. The following increases the maximum shared memory area to
32 MB:
options "SHMALL=8192"
options "SHMMAX=\(SHMALL*PAGE_SIZE\)"
For those running 4.1 or later, just make the above changes, recompile the kernel, and reboot. For
those running earlier releases, use bpatch to find the sysptsize value in the current kernel. This
is computed dynamically at boot time.
$ bpatch -r sysptsize
0x9 = 9
Next, add SYSPTSIZE as a hard-coded value in the kernel configuration file. Increase the value you
found using bpatch. Add 1 for every additional 4 MB of shared memory you desire.
options "SYSPTSIZE=16"
sysptsize cannot be changed by sysctl.
Semaphores. You may need to increase the number of semaphores. By default, PostgreSQL allo-
cates 34 semaphores, which is over half the default system total of 60.
Set the values you want in your kernel configuration file, e.g.:
options "SEMMNI=40"
options "SEMMNS=240"
options "SEMUME=40"
options "SEMMNU=120"
FreeBSD
NetBSD
OpenBSD
The options SYSVSHM and SYSVSEM need to be enabled when the kernel is compiled. (They are by
default.) The maximum size of shared memory is determined by the option SHMMAXPGS (in pages).
The following shows an example of how to set the various parameters:
options SYSVSHM
options SHMMAXPGS=4096
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Chapter 3. Server Run-time Environment
options SHMSEG=256
options SYSVSEM
options SEMMNI=256
options SEMMNS=512
options SEMMNU=256
options SEMMAP=256
(On NetBSD and OpenBSD the key word is actually option singular.)
You may also want to use the sysctl setting to lock shared memory into RAM and prevent it from
being paged out to swap.
HP-UX
The default settings tend to suffice for normal installations. On HP-UX 10, the factory default for
SEMMNS is 128, which might be too low for larger database sites.
IPC parameters can be set in the System Administration Manager (SAM) under Kernel
Configuration−→Configurable Parameters. Hit Create A New Kernel when you’re done.
Linux
The default shared memory limit (both SHMMAX and SHMALL) is 32 MB in 2.2 kernels, but it can be
changed in the proc file system (without reboot). For example, to allow 128 MB:
$ echo 134217728 >/proc/sys/kernel/shmall
$ echo 134217728 >/proc/sys/kernel/shmmax
You could put these commands into a script run at boot-time.
Alternatively, you can use sysctl, if available, to control these parameters. Look for a file called
/etc/sysctl.conf and add lines like the following to it:
kernel.shmall = 134217728
kernel.shmmax = 134217728
This file is usually processed at boot time, but sysctl can also be called explicitly later.
Other parameters are sufficiently sized for any application. If you want to see
for yourself look in /usr/src/linux/include/asm-xxx/shmpara m.h and
/usr/src/linux/include/linux/sem.h.
MacOS X
Edit the file /System/Library/StartupItems/SystemTuning/SystemTuning and change
the following values:
sysctl -w kern.sysv.shmmax
sysctl -w kern.sysv.shmmin
sysctl -w kern.sysv.shmmni
sysctl -w kern.sysv.shmseg
sysctl -w kern.sysv.shmall
These values have the same meanings on MacOS X as those listed for previous operating systems.
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Chapter 3. Server Run-time Environment
SCO OpenServer
In the default configuration, only 512 kB of shared memory per segment is allowed, which is about
enough for -B 24 -N 12. To increase the setting, first change directory to /etc/conf/cf.d. To
display the current value of SHMMAX, in bytes, run
./configure -y SHMMAX
To set a new value for SHMMAX, run:
./configure SHMMAX=value
where value is the new value you want to use (in bytes). After setting SHMMAX, rebuild the kernel
./link_unix
and reboot.
Solaris
At least in version 2.6, the default maximum size of a shared memory segments is too low for Post-
greSQL. The relevant settings can be changed in /etc/system, for example:
set shmsys:shminfo_shmmax=0x2000000
set shmsys:shminfo_shmmin=1
set shmsys:shminfo_shmmni=256
set shmsys:shminfo_shmseg=256
set semsys:seminfo_semmap=256
set semsys:seminfo_semmni=512
set semsys:seminfo_semmns=512
set semsys:seminfo_semmsl=32
You need to reboot for the changes to take effect.
See also http://www.sunworld.com/swol-09-1997/swol-09-insidesolaris.html for information on
shared memory under Solaris.
UnixWare
On UnixWare 7, the maximum size for shared memory segments is 512 kB in the default configura-
tion. This is enough for about -B 24 -N 12. To display the current value of SHMMAX, run
/etc/conf/bin/idtune -g SHMMAX
which displays the current, default, minimum, and maximum values, in bytes. To set a new value for
SHMMAX, run:
/etc/conf/bin/idtune SHMMAX value
where value is the new value you want to use (in bytes). After setting SHMMAX, rebuild the kernel
/etc/conf/bin/idbuild -B
and reboot.
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Chapter 3. Server Run-time Environment
3.5.2. Resource Limits
Unix-like operating systems enforce various kinds of resource limits that might interfere with the opera-
tion of your PostgreSQL server. Of particular importance are limits on the number of processes per user,
the number of open files per process, and the amount of memory available to each process. Each of these
have a “hard” and a “soft” limit. The soft limit is what actually counts but it can be changed by the user
up to the hard limit. The hard limit can only be changed by the root user. The system call setrlimit is
responsible for setting these parameters. The shell’s built-in command ulimit (Bourne shells) or limit
(csh) is used to control the resource limits from the command line. On BSD-derived systems the file
/etc/login.conf controls the various resource limits set during login. See login.conf for details. The
relevant parameters are maxproc, openfiles, and datasize. For example:
default:\
...
:datasize-cur=256M:\
:maxproc-cur=256:\
:openfiles-cur=256:\
...
(-cur is the soft limit. Append -max to set the hard limit.)
Kernels can also have system-wide limits on some resources.
• On Linux /proc/sys/fs/file-max determines the maximum number of open files that the kernel
will support. It can be changed by writing a different number into the file or by adding an assignment in
/etc/sysctl.conf. The maximum limit of files per process is fixed at the time the kernel is compiled;
see /usr/src/linux/Documentation/proc.txt for more information.
The PostgreSQL server uses one process per connection so you should provide for at least as many pro-
cesses as allowed connections, in addition to what you need for the rest of your system. This is usually
not a problem but if you run several servers on one machine things might get tight.
The factory default limit on open files is often set to “socially friendly” values that allow many users to
coexist on a machine without using an inappropriate fraction of the system resources. If you run many
servers on a machine this is perhaps what you want, but on dedicated servers you may want to raise this
limit.
On the other side of the coin, some systems allow individual processes to open large numbers of files; if
more than a few processes do so then the system-wide limit can easily be exceeded. If you find this happen-
ing, and don’t want to alter the system-wide limit, you can set PostgreSQL’s max_files_per_process
configuration parameter to limit the consumption of open files.
3.6. Shutting Down the Server
There are several ways to shut down the database server. You control the type of shutdown by sending
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Chapter 3. Server Run-time Environment
different signals to the server process.
SIGTERM
After receiving SIGTERM, the postmaster disallows new connections, but lets existing backends end
their work normally. It shuts down only after all of the backends terminate normally. This is Smart
Shutdown.
SIGINT
The postmaster disallows new connections and sends all existing backends SIGTERM, which will
cause them to abort their current transactions and exit promptly. It then waits for the backends to exit
and finally shuts down. This is Fast Shutdown.
SIGQUIT
This is Immediate Shutdown, which will cause the postmaster to send a SIGQUIT to all backends and
exit immediately (without properly shutting itself down). The backends likewise exit immediately
upon receiving SIGQUIT. This will lead to recovery (by replaying the WAL log) upon next start-up.
This is recommended only in emergencies.
Important: It is best not to use SIGKILL to shut down the postmaster. This will prevent the postmaster
from releasing shared memory and semaphores, which may then have to be done by manually.
The PID of the postmaster process can be found using the ps program, or from the file postmaster.pid
in the data directory. So for example, to do a fast shutdown:
$ kill -INT ‘head -1 /usr/local/pgsql/data/postmaster.pid‘
The program pg_ctl is a shell script that provides a more convenient interface for shutting down the
postmaster.
3.7. Secure TCP/IP Connections with SSL
PostgreSQL has native support for using SSL connections to encrypt client/server communications for
increased security. This requires OpenSSL be installed on both client and server systems and support
enabled at build time (see Chapter 1).
With SSL support compiled in, the PostgreSQL server can be started with SSL support by setting the
parameter ssl to on in postgresql.conf. When starting in SSL mode, the server will look for the files
server.key and server.crt in the data directory. These files should contain the server private key and
certificate respectively. These files must be set up correctly before an SSL-enabled server can start. If the
private key is protected with a passphrase, the server will prompt for the passphrase and will not start until
it has been entered.
The server will listen for both standard and SSL connections on the same TCP/IP port, and will negotiate
with any connecting client on whether to use SSL. See Chapter 6 about how to force the server to require
use of SSL for certain connections.
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Chapter 3. Server Run-time Environment
For details on how to create your server private key and certificate, refer to the OpenSSL documentation.
A simple self-signed certificate can be used to get started for testing, but a certificate signed by a certificate
authority (CA) (either one of the global CAs or a local one) should be used in production so the client can
verify the server’s identity. To create a quick self-signed certificate, use the following OpenSSL command:
openssl req -new -text -out server.req
Fill out the information that openssl asks for. Make sure that you enter the local host name as Common
Name; the challenge password can be left blank. The script will generate a key that is passphrase protected;
it will not accept a passphrase that is less than four characters long. To remove the passphrase (as you must
if you want automatic start-up of the server), run the commands
openssl rsa -in privkey.pem -out server.key
rm privkey.pem
Enter the old passphrase to unlock the existing key. Now do
openssl req -x509 -in server.req -text -key server.key -out server.crt
chmod og-rwx server.key
to turn the certificate into a self-signed certificate and to copy the key and certificate to where the server
will look for them.
3.8. Secure TCP/IP Connections with SSH Tunnels
Acknowledgement: Idea taken from an email by Gene Selkov, Jr. (<[email protected]>) writ-
ten on 1999-09-08 in response to a question from Eric Marsden.
One can use SSH to encrypt the network connection between clients and a PostgreSQL server. Done
properly, this provides an adequately secure network connection.
First make sure that an SSH server is running properly on the same machine as PostgreSQL and that you
can log in using ssh as some user. Then you can establish a secure tunnel with a command like this from
the client machine:
ssh -L 3333:foo.com:5432 [email protected]
The first number in the -L argument, 3333, is the port number of your end of the tunnel; it can be chosen
freely. The second number, 5432, is the remote end of the tunnel -- the port number your server is using.
The name or the address in between the port numbers is the host with the database server you are going
to connect to. In order to connect to the database server using this tunnel, you connect to port 3333 on the
local machine:
psql -h localhost -p 3333 template1
To the database server it will then look as though you are really user [email protected] and it will use
whatever authentication procedure was set up for this user. In order for the tunnel setup to succeed you
must be allowed to connect via ssh as [email protected], just as if you had attempted to use ssh to set up a
terminal session.
45
Chapter 3. Server Run-time Environment
Tip: Several other applications exist that can provide secure tunnels using a procedure similar in
concept to the one just described.
46
Chapter 4. Database Users and Privileges
Every database cluster contains a set of database users. Those users are separate from the users managed
by the operating system on which the server runs. Users own database objects (for example, tables) and
can assign privileges on those objects to other users to control who has access to which object.
This chapter describes how to create and manage users and introduces the privilege system. More in-
formation about the various types of database objects and the effects of privileges can be found in the
PostgreSQL User’s Guide.
4.1. Database Users
Database users are conceptually completely separate from operating system users. In practice it might be
convenient to maintain a correspondence, but this is not required. Database user names are global across
a database cluster installation (and not per individual database). To create a user use the CREATE USER
SQL command:
CREATE USER name
name follows the rules for SQL identifiers: either unadorned without special characters, or double-quoted.
To remove an existing user, use the analogous DROP USER command:
DROP USER name
For convenience, the programs createuser and dropuser are provided as wrappers around these SQL com-
mands that can be called from the shell command line:
createuser name
dropuser name
In order to bootstrap the database system, a freshly initialized system always contains one predefined
user. This user will have the fixed ID 1, and by default (unless altered when running initdb) it will have
the same name as the operating system user that initialized the database cluster. Customarily, this user
will be named postgres. In order to create more users you first have to connect as this initial user.
Exactly one user identity is active for a connection to the database server. The user name to use for a
particular database connection is indicated by the client that is initiating the connection request in an
application-specific fashion. For example, the psql program uses the -U command line option to indicate
the user to connect as. Many applications assume the name of the current operating system user by default
(including createuser and psql). Therefore it is convenient to maintain a naming correspondence between
the two user sets.
The set of database users a given client connection may connect as is determined by the client authentica-
tion setup, as explained in Chapter 6. (Thus, a client is not necessarily limited to connect as the user with
the same name as its operating system user, in the same way a person is not constrained in its login name
by her real name.) Since the user identity determines the set of privileges available to a connected client,
it is important to carefully configure this when setting up a multiuser environment.
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Chapter 4. Database Users and Privileges
4.2. User Attributes
A database user may have a number of attributes that define its privileges and interact with the client
authentication system.
superuser
A database superuser bypasses all permission checks. Also, only a superuser can create new users.
To create a database superuser, use CREATE USER name CREATEUSER.
database creation
A user must be explicitly given permission to create databases (except for superusers, since those
bypass all permission checks). To create such a user, use CREATE USER name CREATEDB.
password
A password is only significant if the client authentication method requires the user to supply a pass-
word when connecting to the database. The password, md5, and crypt authentication methods
make use of passwords. Database passwords are separate from operating system passwords. Specify
a password upon user creation with CREATE USER name PASSWORD ’string’.
A user’s attributes can be modified after creation with ALTER USER. See the reference pages for CREATE
USER and ALTER USER for details.
A user can also set personal defaults for many of the run-time configuration settings described in Section
3.4. For example, if for some reason you want to disable index scans (hint: not a good idea) anytime you
connect, you can use
ALTER USER myname SET enable_indexscan TO off;
This will save the setting (but not set it immediately) and in subsequent connections it will appear as
though SET enable_indexscan TO off; had been called right before the session started. You can
still alter this setting during the session; it will only be the default. To undo any such setting, use ALTER
USER username RESET varname;.
4.3. Groups
As in Unix, groups are a way of logically grouping users to ease management of privileges: privileges can
be granted to, or revoked from, a group as a whole. To create a group, use
CREATE GROUP name
To add users to or remove users from a group, use
ALTER GROUP name ADD USER uname1, ...
ALTER GROUP name DROP USER uname1, ...
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Chapter 4. Database Users and Privileges
4.4. Privileges
When a database object is created, it is assigned an owner. The owner is the user that executed the creation
statement. To change the owner of a table, index, sequence, or view, use the ALTER TABLE command. By
default, only an owner (or a superuser) can do anything with the object. In order to allow other users to
use it, privileges must be granted.
There are several different privileges: SELECT, INSERT, UPDATE, DELETE, RULE, REFERENCES, TRIG-
GER, CREATE, TEMPORARY, EXECUTE, USAGE, and ALL PRIVILEGES. For more information on the dif-
ferent types of privileges support by PostgreSQL, refer to the GRANT page in the PostgreSQL Reference
Manual. The right to modify or destroy an object is always the privilege of the owner only. To assign
privileges, the GRANT command is used. So, if joe is an existing user, and accounts is an existing table,
the privilege to update the table can be granted with
GRANT UPDATE ON accounts TO joe;
The user executing this command must be the owner of the table. To grant a privilege to a group, use
GRANT SELECT ON accounts TO GROUP staff;
The special “user” name PUBLIC can be used to grant a privilege to every user on the system. Writing
ALL in place of a specific privilege specifies that all privileges will be granted.
To revoke a privilege, use the fittingly named REVOKE command:
REVOKE ALL ON accounts FROM PUBLIC;
The special privileges of the table owner (i.e., the right to do DROP, GRANT, REVOKE, etc) are always
implicit in being the owner, and cannot be granted or revoked. But the table owner can choose to revoke
his own ordinary privileges, for example to make a table read-only for himself as well as others.
4.5. Functions and Triggers
Functions and triggers allow users to insert code into the backend server that other users may execute
without knowing it. Hence, both mechanisms permit users to Trojan horse others with relative impunity.
The only real protection is tight control over who can define functions.
Functions written in any language except SQL run inside the backend server process with the operating
systems permissions of the database server daemon process. It is possible to change the server’s internal
data structures from inside of trusted functions. Hence, among many other things, such functions can
circumvent any system access controls. This is an inherent problem with user-defined C functions.
49
Chapter 5. Managing Databases
Every instance of a running PostgreSQL server manages one or more databases. Databases are therefore
the topmost hierarchical level for organizing SQL objects (“database objects”). This chapter describes the
properties of databases, and how to create, manage, and destroy them.
5.1. Overview
A database is a named collection of SQL objects (“database objects”). Generally, every database object
(tables, functions, etc.) belongs to one and only one database. (But there are a few system catalogs, for
example pg_database, that belong to a whole installation and are accessible from each database within
the installation.) More accurately, a database is a collection of schemas and the schemas contain the
tables, functions, etc. So the full hierarchy is: server, database, schema, table (or something else instead
of a table).
An application that connects to the database server specifies in its connection request the name of the
database it wants to connect to. It is not possible to access more than one database per connection. (But
an application is not restricted in the number of connections it opens to the same or other databases.) It
is possible, however, to access more than one schema from the same connection. Schemas are a purely
logical structure and who can access what is managed by the privilege system. Databases are physically
separated and access control is managed at the connection level. If one PostgreSQL server instance is to
house projects or users that should be separate and for the most part unaware of each other, it is therefore
recommendable to put them into separate databases. If the projects or users are interrelated and should
be able to use each other’s resources they should be put in the same databases but possibly into separate
schemas. More information about managing schemas is in the PostgreSQL User’s Guide.
Note: SQL calls databases “catalogs”, but there is no difference in practice.
5.2. Creating a Database
In order to create a databases, the PostgreSQL server must be up and running (see Section 3.3).
Databases are created with the query language command CREATE DATABASE:
CREATE DATABASE name
where name follows the usual rules for SQL identifiers. The current user automatically becomes the
owner of the new database. It is the privilege of the owner of a database to remove it later on (which also
removes all the objects in it, even if they have a different owner).
The creation of databases is a restricted operation. See Section 4.2 for how to grant permission.
Since you need to be connected to the database server in order to execute the CREATE DATABASE com-
mand, the question remains how the first database at any given site can be created. The first database is
always created by the initdb command when the data storage area is initialized. (See Section 3.2.) By
convention this database is called template1. So to create the first “real” database you can connect to
template1.
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Chapter 5. Managing Databases
The name “template1” is no accident: When a new database is created, the template database is essen-
tially cloned. This means that any changes you make in template1 are propagated to all subsequently
created databases. This implies that you should not use the template database for real work, but when used
judiciously this feature can be convenient. More details appear in Section 5.3.
As an extra convenience, there is also a program that you can execute from the shell to create new
databases, createdb.
createdb dbname
createdb does no magic. It connects to the template1 database and issues the CREATE DATABASE com-
mand, exactly as described above. It uses the psql program internally. The reference page on createdb
contains the invocation details. Note that createdb without any arguments will create a database with
the current user name, which may or may not be what you want.
Note: Chapter 6 contains information about how to restrict who can connect to a given database.
Sometimes you want to create a database for someone else. That user should become the owner of the new
database, so he can configure and manage it himself. To achieve that, use one of the following commands:
CREATE DATABASE dbname OWNER username;
from the SQL environment, or
createdb -O username dbname
You must be a superuser to be allowed to create a database for someone else.
5.3. Template Databases
CREATE DATABASE actually works by copying an existing database. By default, it copies the standard
system database named template1. Thus that database is the “template” from which new databases
are made. If you add objects to template1, these objects will be copied into subsequently created user
databases. This behavior allows site-local modifications to the standard set of objects in databases. For ex-
ample, if you install the procedural language PL/pgSQL in template1, it will automatically be available
in user databases without any extra action being taken when those databases are made.
There is a second standard system database named template0. This database contains the same data
as the initial contents of template1, that is, only the standard objects predefined by your version of
PostgreSQL. template0 should never be changed after initdb. By instructing CREATE DATABASE to
copy template0 instead of template1, you can create a “virgin” user database that contains none of
the site-local additions in template1. This is particularly handy when restoring a pg_dump dump: the
dump script should be restored in a virgin database to ensure that one recreates the correct contents of the
dumped database, without any conflicts with additions that may now be present in template1.
To create a database by copying template0, use
CREATE DATABASE dbname TEMPLATE template0;
from the SQL environment, or
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Chapter 5. Managing Databases
createdb -T template0 dbname
from the shell.
It is possible to create additional template databases, and indeed one might copy any database in an in-
stallation by specifying its name as the template for CREATE DATABASE. It is important to understand,
however, that this is not (yet) intended as a general-purpose “COPY DATABASE” facility. In particular, it is
essential that the source database be idle (no data-altering transactions in progress) for the duration of the
copying operation. CREATE DATABASE will check that no backend processes (other than itself) are con-
nected to the source database at the start of the operation, but this does not guarantee that changes cannot
be made while the copy proceeds, which would result in an inconsistent copied database. Therefore, we
recommend that databases used as templates be treated as read-only.
Two useful flags exist in pg_database for each database: the columns datistemplate and datal-
lowconn. datistemplate may be set to indicate that a database is intended as a template for CREATE
DATABASE. If this flag is set, the database may be cloned by any user with CREATEDB privileges; if it is not
set, only superusers and the owner of the database may clone it. If datallowconn is false, then no new
connections to that database will be allowed (but existing sessions are not killed simply by setting the flag
false). The template0 database is normally marked datallowconn = false to prevent modification of
it. Both template0 and template1 should always be marked with datistemplate = true.
After preparing a template database, or making any changes to one, it is a good idea to perform VACUUM
FREEZE or VACUUM FULL FREEZE in that database. If this is done when there are no other open transac-
tions in the same database, then it is guaranteed that all tuples in the database are “frozen” and will not
be subject to transaction ID wraparound problems. This is particularly important for a database that will
have datallowconn set to false, since it will be impossible to do routine maintenance VACUUMs on such
a database. See Section 8.2.3 for more information.
Note: template1 and template0 do not have any special status beyond the fact that the name
template1 is the default source database name for CREATE DATABASE and the default database-
to-connect-to for various programs such as createdb. For example, one could drop template1 and
recreate it from template0 without any ill effects. This course of action might be advisable if one has
carelessly added a bunch of junk in template1.
5.4. Database Configuration
Recall from Section 3.4 that the PostgreSQL server provides a large number of run-time configuration
variables. You can set database-specific default values for many of these settings.
For example, if for some reason you want to disable the GEQO optimizer for a given database, you’d
ordinarily have to either disable it for all databases or make sure that every connecting client is careful to
issue SET geqo TO off;. To make this setting the default you can execute the command
ALTER DATABASE mydb SET geqo TO off;
This will save the setting (but not set it immediately) and in subsequent connections it will appear as
though SET geqo TO off; had been called right before the session started. Note that users can still
alter this setting during the session; it will only be the default. To undo any such setting, use ALTER
DATABASE dbname RESET varname;.
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Chapter 5. Managing Databases
5.5. Alternative Locations
It is possible to create a database in a location other than the default location for the installation. Remember
that all database access occurs through the database server, so any location specified must be accessible
by the server.
Alternative database locations are referenced by an environment variable which gives the absolute path to
the intended storage location. This environment variable must be present in the server’s environment, so
it must have been defined before the server was started. (Thus, the set of available alternative locations
is under the site administrator’s control; ordinary users can’t change it.) Any valid environment variable
name may be used to reference an alternative location, although using variable names with a prefix of
PGDATA is recommended to avoid confusion and conflict with other variables.
To create the variable in the environment of the server process you must first shut down the server, define
the variable, initialize the data area, and finally restart the server. (See Section 3.6 and Section 3.3.) To set
an environment variable, type
PGDATA2=/home/postgres/data
export PGDATA2
in Bourne shells, or
setenv PGDATA2 /home/postgres/data
in csh or tcsh. You have to make sure that this environment variable is always defined in the server
environment, otherwise you won’t be able to access that database. Therefore you probably want to set it
in some sort of shell start-up file or server start-up script.
To create a data storage area in PGDATA2, ensure that the containing directory (here, /home/postgres)
already exists and is writable by the user account that runs the server (see Section 3.1). Then from the
command line, type
initlocation PGDATA2
(not initlocation $PGDATA2). Then you can restart the server.
To create a database within the new location, use the command
CREATE DATABASE name WITH LOCATION = ’location’
where location is the environment variable you used, PGDATA2 in this example. The createdb com-
mand has the option -D for this purpose.
Databases created in alternative locations can be accessed and dropped like any other database.
Note: It can also be possible to specify absolute paths directly to the CREATE DATABASE command
without defining environment variables. This is disallowed by default because it is a security risk. To
allow it, you must compile PostgreSQL with the C preprocessor macro ALLOW_ABSOLUTE_DBPATHS
defined. One way to do this is to run the compilation step like this:
gmake CPPFLAGS=-DALLOW_ABSOLUTE_DBPATHS all
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Chapter 5. Managing Databases
5.6. Destroying a Database
Databases are destroyed with the command DROP DATABASE:
DROP DATABASE name
Only the owner of the database (i.e., the user that created it), or a superuser, can drop a database. Dropping
a database removes all objects that were contained within the database. The destruction of a database
cannot be undone.
You cannot execute the DROP DATABASE command while connected to the victim database. You can,
however, be connected to any other database, including the template1 database, which would be the
only option for dropping the last user database of a given cluster.
For convenience, there is also a shell program to drop databases:
dropdb dbname
(Unlike createdb, it is not the default action to drop the database with the current user name.)
54
Chapter 6. Client Authentication
When a client application connects to the database server, it specifies which PostgreSQL user name it
wants to connect as, much the same way one logs into a Unix computer as a particular user. Within the
SQL environment the active database user name determines access privileges to database objects -- see
Chapter 4 for more information. Therefore, it is essential to restrict which database users can connect.
Authentication is the process by which the database server establishes the identity of the client, and by ex-
tension determines whether the client application (or the user who runs the client application) is permitted
to connect with the user name that was requested.
PostgreSQL offers a number of different client authentication methods. The method used to authenticate
a particular client connection can be selected on the basis of (client) host address, database, and user.
PostgreSQL user names are logically separate from user names of the operating system in which the server
runs. If all the users of a particular server also have accounts on the server’s machine, it makes sense to
assign database user names that match their operating system user names. However, a server that accepts
remote connections may have many users who have no local account, and in such cases there need be no
connection between database user names and OS user names.
6.1. The pg_hba.conf file
Client authentication is controlled by the file pg_hba.conf in the data directory, e.g.,
/usr/local/pgsql/data/pg_hba.conf. (HBA stands for host-based authentication.) A default
pg_hba.conf file is installed when the data directory is initialized by initdb.
The general format of the pg_hba.conf file is a set of records, one per line. Blank lines are ignored, as is
any text after the “#” comment character. A record is made up of a number of fields which are separated by
spaces and/or tabs. Fields can contain white space if the field value is quoted. Records cannot be continued
across lines.
Each record specifies a connection type, a client IP address range (if relevant for the connection type),
a database name, a user name, and the authentication method to be used for connections matching these
parameters. The first record with a matching connection type, client address, requested database, and user
name is used to perform authentication. There is no “fall-through” or “backup”: if one record is chosen
and the authentication fails, subsequent records are not considered. If no record matches, access is denied.
A record may have one of the three formats
local database user authentication-method [authentication-option]
host database user IP-address IP-mask authentication-method [authentication-
option]
hostssl database user IP-address IP-mask authentication-method [authentication-
option]
The meaning of the fields is as follows:
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Chapter 6. Client Authentication
local
This record matches connection attempts using Unix domain sockets. Without a record of this type,
Unix-domain socket connections are disallowed
host
This record matches connection attempts using TCP/IP networks. Note that TCP/IP connections are
disabled unless the server is started with the -i option or the tcpip_socket postgresql.conf
configuration parameter is enabled.
hostssl
This record matches connection attempts using SSL over TCP/IP. host records will match either
SSL or non-SSL connection attempts, but hostssl records require SSL connections.
To be able make use of this option the server must be built with SSL support enabled. Furthermore,
SSL must be enabled by enabling the option ssl in postgresql.conf (see Section 3.4).
database
Specifies which databases this record matches. The value all specifies that it matches all databases.
The value sameuser specifies that the record matches if the requested database has the same name
as the requested user. The value samegroup specifies that the requested user must a member of
the group with the same name as the requested database. Otherwise, this is the name of a specific
PostgreSQL database. Multiple database names can be supplied by separating them with commas. A
file containing database names can be specified by preceding the file name with @. The file must be
in the same directory as pg_hba.conf.
user
Specifies which PostgreSQL users this record matches. The value all specifies that it matches all
users. Otherwise, this is the name of a specific PostgreSQL user. Multiple user names can be supplied
by separating them with commas. Group names can be specified by preceding the group name with
+. A file containing user names can be specified by preceding the file name with @. The file must be
in the same directory as pg_hba.conf.
IP-address
IP-mask
These two fields contain IP address/mask values in standard dotted decimal notation. (IP addresses
can only be specified numerically, not as domain or host names.) Taken together they specify the
client machine IP addresses that this record matches. The precise logic is that
(actual-IP-address xor IP-address-field) and IP-mask-field
must be zero for the record to match. (Of course IP addresses can be spoofed but this consideration
is beyond the scope of PostgreSQL.)
These fields only apply to host and hostssl records.
authentication-method
Specifies the authentication method to use when connecting via this record. The possible choices are
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Chapter 6. Client Authentication
summarized here; details are in Section 6.2.
trust
The connection is allowed unconditionally. This method allows anyone that can connect to
the PostgreSQL database to login as any PostgreSQL user they like, without the need for a
password. See Section 6.2.1 for details.
reject
The connection is rejected unconditionally. This is useful for “filtering out” certain hosts from
a group.
md5
Requires the client to supply an MD5 encrypted password for authentication. This is the only
method that allows encrypted passwords to be stored in pg_shadow. See Section 6.2.2 for
details.
crypt
Like md5 method but uses older crypt encryption, which is needed for pre-7.2 clients. md5 is
preferred for 7.2 and later clients. See Section 6.2.2 for details.
password
Same as "md5", but the password is sent in clear text over the network. This should not be used
on untrusted networks. See Section 6.2.2 for details.
krb4
Kerberos V4 is used to authenticate the user. This is only available for TCP/IP connections. See
Section 6.2.3 for details.
krb5
Kerberos V5 is used to authenticate the user. This is only available for TCP/IP connections. See
Section 6.2.3 for details.
ident
Obtain the operating system user name of the client (for TCP/IP connections by contacting the
ident server on the client, for local connections by getting it from the operating system) and
check if the user is allowed to connect as the requested database user by consulting the map
specified after the ident key word.
If you use the map sameuser, the user names are assumed to be identical. If not, the map
name is looked up in the file pg_ident.conf in the same directory as pg_hba.conf. The
connection is accepted if that file contains an entry for this map name with the ident-supplied
user name and the requested PostgreSQL user name.
For local connections, this only works on machines that support Unix-domain socket credentials
(currently Linux, FreeBSD, NetBSD, and BSD/OS).
See Section 6.2.4 below for details.
pam
Authenticate using the Pluggable Authentication Modules (PAM) service provided by the oper-
ating system. See Section 6.2.5 for details.
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Chapter 6. Client Authentication
authentication-option
The meaning of this optional field depends on the chosen authentication method and is described in
the next section.
Since the pg_hba.conf records are examined sequentially for each connection attempt, the order of the
records is significant. Typically, earlier records will have tight connection match parameters and weaker
authentication methods, while later records will have looser match parameters and stronger authentica-
tion methods. For example, one might wish to use trust authentication for local TCP connections but
require a password for remote TCP connections. In this case a record specifying trust authentication for
connections from 127.0.0.1 would appear before a record specifying password authentication for a wider
range of allowed client IP addresses.
Important: Do not prevent the superuser from accessing the template1 database. Various utility com-
mands need access to template1.
The pg_hba.conf file is read on start-up and when the postmaster receives a SIGHUP signal. If you
edit the file on an active system, you will need to signal the postmaster (using pg_ctl reload or kill
-HUP) to make it re-read the file.
An example of a pg_hba.conf file is shown in Example 6-1. See below for details on the different
authentication methods.
Example 6-1. An example pg_hba.conf file
# Allow any user on the local system to connect to any database under
# any user name using Unix-domain sockets (the default for local
# connections).
#
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
local all all trust
# The same using local loopback TCP/IP connections.
#
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
host all all 127.0.0.1 255.255.255.255 trust
# Allow any user from any host with IP address 192.168.93.x to connect
# to database "template1" as the same user name that ident reports for
# the connection (typically the Unix user name).
#
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
host template1 all 192.168.93.0 255.255.255.0 ident sameuser
# Allow a user from host 192.168.12.10 to connect to database
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Chapter 6. Client Authentication
# "template1" if the user’s password is correctly supplied.
#
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
host template1 all 192.168.12.10 255.255.255.255 md5
# In the absence of preceding "host" lines, these two lines will
# reject all connection from 192.168.54.1 (since that entry will be
# matched first), but allow Kerberos V connections from anywhere else
# on the Internet. The zero mask means that no bits of the host IP
# address are considered so it matches any host.
#
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
host all all 192.168.54.1 255.255.255.255 reject
host all all 0.0.0.0 0.0.0.0 krb5
# Allow users from 192.168.x.x hosts to connect to any database, if
# they pass the ident check. If, for example, ident says the user is
# "bryanh" and he requests to connect as PostgreSQL user "guest1", the
# connection is allowed if there is an entry in pg_ident.conf for map
# "omicron" that says "bryanh" is allowed to connect as "guest1".
#
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
host all all 192.168.0.0 255.255.0.0 ident omicron
# If these are the only three lines for local connections, they will
# allow local users to connect only to their own databases (databases
# with the same name as their user name) except for administrators and
# members of group "support" who may connect to all databases. The file
# $PGDATA/admins contains a list of user names. Passwords are required in
# all cases.
#
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
local sameuser all md5
local all @admins md5
local all +support md5
# The last two lines above can be combined into a single line:
local all @admins,+support md5
# The database column can also use lists and file names, but not groups:
local db1,db2,@demodbs all md5
6.2. Authentication methods
The following describes the authentication methods in more detail.
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Chapter 6. Client Authentication
6.2.1. Trust authentication
When trust authentication is specified, PostgreSQL assumes that anyone who can connect to the server
is authorized to access the database as whatever database user he specifies (including the database supe-
ruser). This method should only be used when there is adequate system-level protection on connections
to the postmaster port.
trust authentication is appropriate and very convenient for local connections on a single-user worksta-
tion. It is usually not appropriate by itself on a multiuser machine. However, you may be able to use trust
even on a multiuser machine, if you restrict access to the postmaster’s socket file using file-system permis-
sions. To do this, set the parameter unix_socket_permissions (and possibly unix_socket_group)
in postgresql.conf, as described in Section 3.4.4. Or you could set unix_socket_directory to
place the socket file in a suitably restricted directory.
Setting file-system permissions only helps for Unix-socket connections. Local TCP connections are
not restricted by it; therefore, if you want to use permissions for local security, remove the host ...
127.0.0.1 ... line from pg_hba.conf, or change it to a non-trust authentication method.
trust authentication is only suitable for TCP connections if you trust every user on every machine that
is allowed to connect to the server by the pg_hba.conf lines that specify trust. It is seldom reasonable
to use trust for any TCP connections other than those from localhost (127.0.0.1).
6.2.2. Password authentication
Password-based authentication methods include md5, crypt, and password. These methods operate sim-
ilarly except for the way that the password is sent across the connection. If you are at all concerned about
password “sniffing” attacks then md5 is preferred, with crypt a second choice if you must support pre-7.2
clients. Plain password should especially be avoided for connections over the open Internet (unless you
use SSL, SSH, or other communications security wrappers around the connection).
PostgreSQL database passwords are separate from operating system user passwords. The password for
each database user is stored in the pg_shadow system catalog table. Passwords can be managed with the
query language commands CREATE USER and ALTER USER, e.g., CREATE USER foo WITH PASS-
WORD ’secret’;. By default, that is, if no password has been set up, the stored password is null and
password authentication will always fail for that user.
To restrict the set of users that are allowed to connect to certain databases, list the users separated by
commas, or in a separate file. The file should contain user names separated by commas or one user name
per line, and be in the same directory as pg_hba.conf. Mention the (base) name of the file preceded with
@ in the user column. The database column can similarly accept a list of values or a file name. You can
also specify group names by preceding the group name with +.
6.2.3. Kerberos authentication
Kerberos is an industry-standard secure authentication system suitable for distributed computing over a
public network. A description of the Kerberos system is far beyond the scope of this document; in all
generality it can be quite complex (yet powerful). The Kerberos FAQ
1
or MIT Project Athena
2
can be a
good starting point for exploration. Several sources for Kerberos distributions exist.
1. http://www.nrl.navy.mil/CCS/people/kenh/kerberos-faq.html
2. ftp://athena-dist.mit.edu
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Chapter 6. Client Authentication
In order to use Kerberos, support for it must be enabled at build time. See Chapter 1 for more information.
Both Kerberos 4 and 5 are supported, but only one version can be supported in any one build.
PostgreSQL operates like a normal Kerberos service. The name of the service principal is service-
name/hostname@realm, where servicename is postgres (unless a different service name was
selected at configure time with ./configure --with-krb-srvnam=whatever). hostname is the
fully qualified domain name of the server machine. The service principal’s realm is the preferred realm of
the server machine.
Client principals must have their PostgreSQL user name as their first component, for example pguser-
name/otherstuff@realm. At present the realm of the client is not checked by PostgreSQL; so if
you have cross-realm authentication enabled, then any principal in any realm that can communicate with
yours will be accepted.
Make sure that your server key file is readable (and preferably only readable) by the PostgreSQL server
account (see Section 3.1). The location of the key file is specified with the krb_server_keyfile run
time configuration parameter. (See also Section 3.4.) The default is /etc/srvtab if you are using Ker-
beros 4 and FILE:/usr/local/pgsql/etc/krb5.keytab (or whichever directory was specified as
sysconfdir at build time) with Kerberos 5.
To generate the keytab file, use for example (with version 5)
kadmin% ank -randkey postgres/server.my.domain.org
kadmin% ktadd -k krb5.keytab postgres/server.my.domain.org
Read the Kerberos documentation for details.
When connecting to the database make sure you have a ticket for a principal matching the requested
If you use mod_auth_krb and mod_perl on your Apache web server, you can use AuthType Ker-
berosV5SaveCredentials with a mod_perl script. This gives secure database access over the web,
no extra passwords required.
6.2.4. Ident-based authentication
The ident authentication method works by inspecting the client’s operating system user name and de-
termining the allowed database user names by using a map file that lists the permitted corresponding
user name pairs. The determination of the client’s user name is the security-critical point, and it works
differently depending on the connection type.
6.2.4.1. Ident Authentication over TCP/IP
The “Identification Protocol” is described in RFC 1413. Virtually every Unix-like operating system ships
with an ident server that listens on TCP port 113 by default. The basic functionality of an ident server is
to answer questions like “What user initiated the connection that goes out of your port X and connects
to my port Y?”. Since PostgreSQL knows both X and Y when a physical connection is established, it
can interrogate the ident server on the host of the connecting client and could theoretically determine the
operating system user for any given connection this way.
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Chapter 6. Client Authentication
The drawback of this procedure is that it depends on the integrity of the client: if the client machine is
untrusted or compromised an attacker could run just about any program on port 113 and return any user
name he chooses. This authentication method is therefore only appropriate for closed networks where
each client machine is under tight control and where the database and system administrators operate in
close contact. In other words, you must trust the machine running the ident server. Heed the warning:
RFC 1413
The Identification Protocol is not intended as an authorization or access control protocol.
6.2.4.2. Ident Authentication over Local Sockets
On systems supporting SO_PEERCRED requests for Unix-domain sockets (currently Linux, FreeBSD,
NetBSD, and BSD/OS), ident authentication can also be applied to local connections. In this case, no
security risk is added by using ident authentication; indeed it is a preferable choice for local connections
on such systems.
On systems without SO_PEERCRED requests, ident authentication is only available for TCP/IP connec-
tions. As a work around, it is possible to specify the localhost address 127.0.0.1 and make connections to
this address.
6.2.4.3. Ident Maps
When using ident-based authentication, after having determined the name of the operating system user
that initiated the connection, PostgreSQL checks whether that user is allowed to connect as the database
user he is requesting to connect as. This is controlled by the ident map argument that follows the ident
keyword in the pg_hba.conf file. There is a predefined ident map sameuser, which allows any operating
system user to connect as the database user of the same name (if the latter exists). Other maps must be
created manually.
Ident maps other than sameuser are defined in the file pg_ident.conf in the data directory, which
contains lines of the general form:
map-name ident-username database-username
Comments and whitespace are handled in the usual way. The map-name is an arbitrary name that will be
used to refer to this mapping in pg_hba.conf. The other two fields specify which operating system user
is allowed to connect as which database user. The same map-name can be used repeatedly to specify
more user-mappings within a single map. There is no restriction regarding how many database users a
given operating system user may correspond to and vice versa.
The pg_ident.conf file is read on start-up and when the postmaster receives a SIGHUP signal. If you
edit the file on an active system, you will need to signal the postmaster (using pg_ctl reload or kill
-HUP) to make it re-read the file.
A pg_ident.conf file that could be used in conjunction with the pg_hba.conf file in Example 6-1 is
shown in Example 6-2. In this example setup, anyone logged in to a machine on the 192.168 network that
does not have the Unix user name bryanh, ann, or robert would not be granted access. Unix user robert
would only be allowed access when he tries to connect as PostgreSQL user bob, not as robert or anyone
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Chapter 6. Client Authentication
else. ann would only be allowed to connect as ann. User bryanh would be allowed to connect as either
bryanh himself or as guest1.
Example 6-2. An example pg_ident.conf file
# MAPNAME IDENT-USERNAME PG-USERNAME
omicron bryanh bryanh
omicron ann ann
# bob has user name robert on these machines
omicron robert bob
# bryanh can also connect as guest1
omicron bryanh guest1
6.2.5. PAM Authentication
This authentication type operates similarly to password except that it uses PAM (Pluggable Authentication
Modules) as the authentication mechanism. The default PAM service name is postgresql. You can
optionally supply you own service name after the pam keyword in the file. For more information about
PAM, please read the Linux-PAM Page
3
and the Solaris PAM Page
4
.
6.3. Authentication problems
Genuine authentication failures and related problems generally manifest themselves through error mes-
sages like the following.
No pg_hba.conf entry for host 123.123.123.123, user andym, database testdb
This is what you are most likely to get if you succeed in contacting the server, but it does not want to talk
to you. As the message suggests, the server refused the connection request because it found no authorizing
entry in its pg_hba.conf configuration file.
Password authentication failed for user ’andym’
Messages like this indicate that you contacted the server, and it is willing to talk to you, but not until you
pass the authorization method specified in the pg_hba.conf file. Check the password you are providing,
or check your Kerberos or ident software if the complaint mentions one of those authentication types.
FATAL 1: user "andym" does not exist
The indicated user name was not found.
FATAL 1: Database "testdb" does not exist in the system catalog.
3. http://www.kernel.org/pub/linux/libs/pam/
4. http://www.sun.com/software/solaris/pam/
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The database you are trying to connect to does not exist. Note that if you do not specify a database name,
it defaults to the database user name, which may or may not be the right thing.
Note that the server log may contain more information about an authentication failure than is reported to
the client. If you are confused about the reason for a failure, check the log.
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Chapter 7. Localization
Describes the available localization features from the point of view of the administrator.
PostgreSQL supports localization with three approaches:
• Using the locale features of the operating system to provide locale-specific collation order, number
formatting, translated messages, and other aspects.
• Using explicit multiple-byte character sets defined in the PostgreSQL server to support languages that
require more characters than will fit into a single byte, and to provide character set recoding between
client and server. The number of supported character sets is fixed at the time the server is compiled, and
internal operations such as string comparisons require expansion of each character into a 32-bit word.
• Single byte character recoding provides a more light-weight solution for users of multiple, yet single-
byte character sets.
7.1. Locale Support
Locale support refers to an application respecting cultural preferences regarding alphabets, sorting, num-
ber formatting, etc. PostgreSQL uses the standard ISO C and POSIX-like locale facilities provided by the
server operating system. For additional information refer to the documentation of your system.
7.1.1. Overview
Locale support is automatically initialized when a database cluster is created using initdb. initdb will
initialize the database cluster with the locale setting of its execution environment; so if your system is
already set to use the locale that you want in your database cluster then there is nothing else you need to
do. If you want to use a different locale (or you are not sure which locale your system is set to), you can
tell initdb exactly which locale you want with the option --locale. For example:
$ initdb --locale=sv_SE
This example sets the locale to Swedish (sv) as spoken in Sweden (SE). Other possibilities might be
en_US (U.S. English) and fr_CA (Canada, French). If more than one character set can be useful for a
locale then the specifications look like this: cs_CZ.ISO8859-2. What locales are available under what
names on your system depends on what was provided by the operating system vendor and what was
installed.
Occasionally it is useful to mix rules from several locales, e.g., use U.S. collation rules but Spanish
messages. To support that, a set of locale subcategories exist that control only a certain aspect of the
localization rules.
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Chapter 7. Localization
LC_COLLATE String sort order
LC_CTYPE Character classification (What is a letter? The
upper-case equivalent?)
LC_MESSAGES Language of messages
LC_MONETARY Formatting of currency amounts
LC_NUMERIC Formatting of numbers
LC_TIME Formatting of dates and times
The category names translate into names of initdb options to override the locale choice for a specific
category. For instance, to set the locale to French Canadian, but use U.S. rules for formatting currency,
use initdb --locale=fr_CA --lc-monetary=en_US.
If you want the system to behave as if it had no locale support, use the special locale C or POSIX.
The nature of some locale categories is that their value has to be fixed for the lifetime of a database cluster.
That is, once initdb has run, you cannot change them anymore. LC_COLLATE and LC_CTYPE are those
categories. They affect the sort order of indexes, so they must be kept fixed, or indexes on text columns
will become corrupt. PostgreSQL enforces this by recording the values of LC_COLLATE and LC_CTYPE
that are seen by initdb. The server automatically adopts those two values when it is started.
The other locale categories can be changed as desired whenever the server is started by setting the run-
time configuration variables that have the same name as the locale categories (see Section 3.4 for de-
tails). The defaults that are chosen by initdb are actually only written into the configuration file post-
gresql.conf to serve as defaults when the server is started. If you delete the assignments from post-
gresql.conf then the server will inherit the settings from the execution environment.
Note that the locale behavior of the server is determined by the environment variables seen by the server,
not by the environment of any client. Therefore, be careful to configure the correct locale settings before
starting the server. A consequence of this is that if client and server are set up to different locales, messages
may appear in different languages depending on where they originated.
Note: When we speak of inheriting the locale from the execution environment, this means the following
on most operating systems: For a given locale category, say the collation, the following environment
variables are consulted in this order until one is found to be set: LC_ALL, LC_COLLATE (the variable
corresponding to the respective category), LANG. If none of these environment variables are set then
the locale defaults to C.
Some message localization libraries also look at the environment variable LANGUAGE which overrides
all other locale settings for the purpose of setting the language of messages. If in doubt, please
refer to the documentation of your operating system, in particular the gettext manual page, for more
information.
To enable messages translated to the user’s preferred language, the --enable-nls option must be used.
This option is independent of the other locale support.
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7.1.2. Benefits
Locale support influences in particular the following features:
• Sort order in ORDER BY queries.
• The to_char family of functions
• The LIKE and ~ operators for pattern matching
The only severe drawback of using the locale support in PostgreSQL is its speed. So use locale only if you
actually need it. It should be noted in particular that selecting a non-C locale disables index optimizations
for LIKE and ~ operators, which can make a huge difference in the speed of searches that use those
operators.
7.1.3. Problems
If locale support doesn’t work in spite of the explanation above, check that the locale support in your
operating system is correctly configured. To check whether a given locale is installed and functional you
can use Perl, for example. Perl has also support for locales and if a locale is broken perl -v will complain
something like this:
$ export LC_CTYPE=’not_exist’
$ perl -v
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LC_ALL = (unset),
LC_CTYPE = "not_exist",
LANG = (unset)
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
Check that your locale files are in the right location. Possible locations include: /usr/lib/locale
(Linux, Solaris), /usr/share/locale (Linux), /usr/lib/nls/loc (DUX 4.0). Check the locale man
page of your system if you are not sure.
Check that PostgreSQL is actually using the locale that you think it is. LC_COLLATE and LC_CTYPE
settings are determined at initdb time and cannot be changed without repeating initdb. Other locale settings
including LC_MESSAGES and LC_MONETARY are determined by the environment the postmaster is started
in, and can be changed with a simple postmaster restart. You can check the LC_COLLATE and LC_CTYPE
settings of a database with the contrib/pg_controldata utility program.
The directory src/test/locale contains a test suite for PostgreSQL’s locale support.
Client applications that handle server-side errors by parsing the text of the error message will obviously
have problems when the server’s messages are in a different language. If you create such an application
you need to devise a plan to cope with this situation. The embedded SQL interface (ecpg) is also affected
by this problem. It is currently recommended that servers interfacing with ecpg applications be configured
to send messages in English.
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Chapter 7. Localization
Maintaining catalogs of message translations requires the on-going efforts of many volunteers that want to
see PostgreSQL speak their preferred language well. If messages in your language is currently not avail-
able or fully translated, your assistance would be appreciated. If you want to help, refer to the Developer’s
Guide or write to the developers’ mailing list.
7.2. Multibyte Support
Author: Tatsuo Ishii (<[email protected]>), last updated 2002-07-24. Check Tatsuo’s web site
1
for more information.
Multibyte (MB) support is intended to allow PostgreSQL to handle multiple-byte character sets such as
EUC (Extended Unix Code), Unicode, and Mule internal code. With MB enabled you can use multibyte
character sets in regular expressions (regexp), LIKE, and some other functions. The default encoding
system is selected while initializing your PostgreSQL installation using initdb. Note that this can be over-
ridden when you create a database using createdb or by using the SQL command CREATE DATABASE. So
you can have multiple databases each with a different encoding system. Note that MB can handle single
byte characters sets such as ISO-8859-1.
Multibyte support is enabled by default since PostgreSQL version 7.3.
7.2.1. Supported character set encodings
Following encoding can be used as database encoding.
Table 7-1. Character Set Encodings
Encoding Description
SQL_ASCII ASCII
EUC_JP Japanese EUC
EUC_CN Chinese EUC
EUC_KR Korean EUC
JOHAB Korean EUC (Hangle base)
EUC_TW Taiwan EUC
UNICODE Unicode (UTF-8)
MULE_INTERNAL Mule internal code
LATIN1 ISO 8859-1 ECMA-94 Latin Alphabet No.1
LATIN2 ISO 8859-2 ECMA-94 Latin Alphabet No.2
LATIN3 ISO 8859-3 ECMA-94 Latin Alphabet No.3
LATIN4 ISO 8859-4 ECMA-94 Latin Alphabet No.4
LATIN5 ISO 8859-9 ECMA-128 Latin Alphabet No.5
1. http://www.sra.co.jp/people/t-ishii/PostgreSQL/
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Chapter 7. Localization
Encoding Description
LATIN6 ISO 8859-10 ECMA-144 Latin Alphabet No.6
LATIN7 ISO 8859-13 Latin Alphabet No.7
LATIN8 ISO 8859-14 Latin Alphabet No.8
LATIN9 ISO 8859-15 Latin Alphabet No.9
LATIN10 ISO 8859-16 ASRO SR 14111 Latin Alphabet
No.10
ISO-8859-5 ECMA-113 Latin/Cyrillic
ISO-8859-6 ECMA-114 Latin/Arabic
ISO-8859-7 ECMA-118 Latin/Greek
ISO-8859-8 ECMA-121 Latin/Hebrew
KOI8 KOI8-R(U)
WIN Windows CP1251
ALT Windows CP866
WIN1256 Arabic Windows CP1256
TCVN Vietnamese TCVN-5712 (Windows CP1258)
WIN874 Thai Windows CP874
Important: Before PostgreSQL7.2, LATIN5 mistakenly meant ISO 8859-5. From 7.2 on, LATIN5
means ISO 8859-9. If you have a LATIN5 database created on 7.1 or earlier and want to migrate to
7.2 (or later), you should be very careful about this change.
Important: Not all APIs supports all the encodings listed above. For example, the PostgreSQL JDBC
driver does not support MULE_INTERNAL, LATIN6, LATIN8, and LATIN10.
7.2.2. Setting the Encoding
initdb defines the default encoding for a PostgreSQL installation. For example:
$ initdb -E EUC_JP
sets the default encoding to EUC_JP (Extended Unix Code for Japanese). Note that you can use --
encoding instead of -E if you prefer to type longer option strings. If no -E or --encoding option
is given, SQL_ASCII is used.
You can create a database with a different encoding:
$ createdb -E EUC_KR korean
will create a database named korean with EUC_KR encoding. Another way to accomplish this is to use a
SQL command:
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Chapter 7. Localization
CREATE DATABASE korean WITH ENCODING = ’EUC_KR’;
The encoding for a database is represented as an encoding column in the pg_database system catalog.
You can see that by using the -l option or the \l command of psql.
$ psql -l
List of databases
Database | Owner | Encoding
---------------+---------+---------------
euc_cn | t-ishii | EUC_CN
euc_jp | t-ishii | EUC_JP
euc_kr | t-ishii | EUC_KR
euc_tw | t-ishii | EUC_TW
mule_internal | t-ishii | MULE_INTERNAL
regression | t-ishii | SQL_ASCII
template1 | t-ishii | EUC_JP
test | t-ishii | EUC_JP
unicode | t-ishii | UNICODE
(9 rows)
7.2.3. Automatic encoding conversion between server and client
PostgreSQL supports an automatic encoding conversion between server and client for some encodings.
The conversion info is stored in pg_conversion system catalog. You can create a new conversion by
using CREATE CONVERSION. PostgreSQL comes with some predefined conversions. They are listed in
Table 7-2.
Table 7-2. Client/Server Character Set Encodings
Server Encoding Available Client Encodings
SQL_ASCII SQL_ASCII, UNICODE, MULE_INTERNAL
EUC_JP EUC_JP, SJIS, UNICODE, MULE_INTERNAL
EUC_CN EUC_CN, UNICODE, MULE_INTERNAL
EUC_KR EUC_KR, UNICODE, MULE_INTERNAL
JOHAB JOHAB, UNICODE
EUC_TW EUC_TW, BIG5, UNICODE, MULE_INTERNAL
LATIN1 LATIN1, UNICODE MULE_INTERNAL
LATIN2 LATIN2, WIN1250, UNICODE, MULE_INTERNAL
LATIN3 LATIN3, UNICODE, MULE_INTERNAL
LATIN4 LATIN4, UNICODE, MULE_INTERNAL
LATIN5 LATIN5, UNICODE
LATIN6 LATIN6, UNICODE, MULE_INTERNAL
LATIN7 LATIN7, UNICODE, MULE_INTERNAL
LATIN8 LATIN8, UNICODE, MULE_INTERNAL
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Chapter 7. Localization
Server Encoding Available Client Encodings
LATIN9 LATIN9, UNICODE, MULE_INTERNAL
LATIN10 LATIN10, UNICODE, MULE_INTERNAL
ISO_8859_5 ISO_8859_5, UNICODE, MULE_INTERNAL, WIN,
ALT, KOI8
ISO_8859_6 ISO_8859_6, UNICODE
ISO_8859_7 ISO_8859_7, UNICODE
ISO_8859_8 ISO_8859_8, UNICODE
UNICODE EUC_JP, SJIS, EUC_KR, UHC, JOHAB, EUC_CN,
GBK, EUC_TW, BIG5, LATIN1 to LATIN10,
ISO_8859_5, ISO_8859_6, ISO_8859_7,
ISO_8859_8, WIN, ALT, KOI8, WIN1256, TCVN,
WIN874, GB18030, WIN1250
MULE_INTERNAL EUC_JP, SJIS, EUC_KR, EUC_CN, EUC_TW, BIG5,
LATIN1 to LATIN5, WIN, ALT, WIN1250, BIG5,
ISO_8859_5, KOI8
KOI8 ISO_8859_5, WIN, ALT, KOI8, UNICODE,
MULE_INTERNAL
WIN ISO_8859_5, WIN, ALT, KOI8, UNICODE,
MULE_INTERNAL
ALT ISO_8859_5, WIN, ALT, KOI8, UNICODE,
MULE_INTERNAL
WIN1256 WIN1256, UNICODE
TCVN TCVN, UNICODE
WIN874 WIN874, UNICODE
To enable the automatic encoding translation, you have to tell PostgreSQL the encoding you would like
to use in the client. There are several ways to accomplish this.
• Using the \encoding command in psql. \encoding allows you to change client encoding on the fly.
For example, to change the encoding to SJIS, type:
\encoding SJIS
• Using libpq functions. \encoding actually calls PQsetClientEncoding() for its purpose.
int PQsetClientEncoding(PGconn *conn, const char *encoding)
where conn is a connection to the server, and encoding is an encoding you want to use. If it suc-
cessfully sets the encoding, it returns 0, otherwise -1. The current encoding for this connection can be
shown by using:
int PQclientEncoding(const PGconn *conn)
Note that it returns the encoding ID, not a symbolic string such as EUC_JP. To convert an encoding ID
to an encoding name, you can use:
char *pg_encoding_to_char(int encoding_id)
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Chapter 7. Localization
• Using SET CLIENT_ENCODING TO. Setting the client encoding can be done with this SQL command:
SET CLIENT_ENCODING TO ’encoding’;
Also you can use the SQL92 syntax SET NAMES for this purpose:
SET NAMES ’encoding’;
To query the current client encoding:
SHOW CLIENT_ENCODING;
To return to the default encoding:
RESET CLIENT_ENCODING;
• Using PGCLIENTENCODING. If environment variable PGCLIENTENCODING is defined in the client’s
environment, that client encoding is automatically selected when a connection to the server is made.
(This can subsequently be overridden using any of the other methods mentioned above.)
• Using client_encoding variable. If the client_encoding variable in postgresql.conf is set, that
client encoding is automatically selected when a connection to the server is made. (This can subse-
quently be overridden using any of the other methods mentioned above.)
7.2.4. What happens if the translation is not possible?
Suppose you choose EUC_JP for the server and LATIN1 for the client, then some Japanese characters
cannot be translated into LATIN1. In this case, a letter that cannot be represented in the LATIN1 character
set would be transformed as:
(HEXA DECIMAL)
7.2.5. References
These are good sources to start learning about various kinds of encoding systems.
ftp://ftp.ora.com/pub/examples/nutshell/ujip/doc/cjk.inf
Detailed explanations of EUC_JP, EUC_CN, EUC_KR, EUC_TW appear in section 3.2.
http://www.unicode.org/
The web site of the Unicode Consortium
RFC 2044
UTF-8 is defined here.
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7.2.6. History
Dec 7, 2000
* An automatic encoding translation between Unicode and other
encodings are implemented
* Changes above will appear in 7.1
May 20, 2000
* SJIS UDC (NEC selection IBM kanji) support contributed
by Eiji Tokuya
* Changes above will appear in 7.0.1
Mar 22, 2000
* Add new libpq functions PQsetClientEncoding, PQclientEncoding
* ./configure --with-mb=EUC_JP
now deprecated. use
./configure --enable-multibyte=EUC_JP
instead
* Add SQL_ASCII regression test case
* Add SJIS User Defined Character (UDC) support
* All of above will appear in 7.0
July 11, 1999
* Add support for WIN1250 (Windows Czech) as a client encoding
(contributed by Pavel Behal)
* fix some compiler warnings (contributed by Tomoaki Nishiyama)
Mar 23, 1999
* Add support for KOI8(KOI8-R), WIN(CP1251), ALT(CP866)
(thanks Oleg Broytmann for testing)
* Fix problem with MB and locale
Jan 26, 1999
* Add support for Big5 for frontend encoding
(you need to create a database with EUC_TW to use Big5)
* Add regression test case for EUC_TW
(contributed by Jonah Kuo <[email protected]>)
Dec 15, 1998
* Bugs related to SQL_ASCII support fixed
Nov 5, 1998
* 6.4 release. In this version, pg_database has "encoding"
column that represents the database encoding
Jul 22, 1998
* determine encoding at initdb/createdb rather than compile time
* support for PGCLIENTENCODING when issuing COPY command
* support for SQL92 syntax "SET NAMES"
* support for LATIN2-5
* add UNICODE regression test case
* new test suite for MB
* clean up source files
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Chapter 7. Localization
Jun 5, 1998
* add support for the encoding translation between the backend
and the frontend
* new command SET CLIENT_ENCODING etc. added
* add support for LATIN1 character set
* enhance 8-bit cleanliness
April 21, 1998 some enhancements/fixes
* character_length(), position(), substring() are now aware of
multi-byte characters
* add octet_length()
* add --with-mb option to configure
* new regression tests for EUC_KR
(contributed by Soonmyung Hong)
* add some test cases to the EUC_JP regression test
* fix problem in regress/regress.sh in case of System V
* fix toupper(), tolower() to handle 8bit chars
Mar 25, 1998 MB PL2 is incorporated into PostgreSQL 6.3.1
Mar 10, 1998 PL2 released
* add regression test for EUC_JP, EUC_CN and MULE_INTERNAL
* add an English document (this file)
* fix problems concerning 8-bit single byte characters
Mar 1, 1998 PL1 released
7.2.7. WIN1250 on Windows/ODBC
The WIN1250 character set on Windows client platforms can be used with PostgreSQL with locale support
enabled.
The following should be kept in mind:
• Success depends on proper system locales. This has been tested with Red Hat 6.0 and Slackware 3.6,
with the cs_CZ.iso8859-2 locale.
• Never try to set the server’s database encoding to WIN1250. Always use LATIN2 instead since there is
no WIN1250 locale in Unix.
• The WIN1250 encoding is usable only for Windows ODBC clients. The characters are recoded on the
fly, to be displayed and stored back properly.
WIN1250 on Windows/ODBC
1. Compile PostgreSQL with locale enabled and the server-side encoding set to LATIN2.
2. Set up your installation. Do not forget to create locale variables in your environment. For example
(this may not be correct for your environment):
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Chapter 7. Localization
LC_ALL=cs_CZ.ISO8859-2
3. You have to start the server with locales set!
4. Try it with the Czech language, and have it sort on a query.
5. Install ODBC driver for PostgreSQL on your Windows machine.
6. Set up your data source properly. Include this line in your ODBC configuration dialog in the field
Connect Settings:
SET CLIENT_ENCODING = ’WIN1250’;
7. Now try it again, but in Windows with ODBC.
7.3. Single-byte character set recoding
You can set up this feature with the --enable-recode option to configure. This option was formerly
described as “Cyrillic recode support” which doesn’t express all its power. It can be used for any single-
byte character set recoding.
This method uses a file charset.conf file located in the database directory (PGDATA). It’s a typical
configuration text file where spaces and newlines separate items and records and # specifies comments.
Three keywords with the following syntax are recognized here:
BaseCharset server_charset
RecodeTable from_charset to_charset file_name
HostCharset host_spec host_charset
BaseCharset defines the encoding of the database server. All character set names are only used for
mapping inside of charset.conf so you can freely use typing-friendly names.
RecodeTable records specify translation tables between server and client. The file name is relative to
the PGDATA directory. The table file format is very simple. There are no keywords and characters are
represented by a pair of decimal or hexadecimal (0x prefixed) values on single lines:
char_value translated_char_value
HostCharset records define the client character set by IP address. You can use a single IP address,
an IP mask range starting from the given address or an IP interval (e.g., 127.0.0.1, 192.168.1.100/24,
192.168.1.20-192.168.1.40).
The charset.conf file is always processed up to the end, so you can easily specify exceptions from the
previous rules. In the src/data/ directory you will find an example charset.conf and a few recoding
tables.
As this solution is based on the client’s IP address and character set mapping there are obviously some
restrictions as well. You cannot use different encodings on the same host at the same time. It is also
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Chapter 7. Localization
inconvenient when you boot your client hosts into multiple operating systems. Nevertheless, when these
restrictions are not limiting and you do not need multibyte characters then it is a simple and effective
solution.
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Chapter 8. Routine Database Maintenance
Tasks
8.1. General Discussion
There are a few routine maintenance chores that must be performed on a regular basis to keep a Post-
greSQL installation running smoothly. The tasks discussed here are repetitive in nature and can easily be
automated using standard Unix tools such as cron scripts. But it is the database administrator’s responsi-
bility to set up appropriate scripts, and to check that they execute successfully.
One obvious maintenance task is creation of backup copies of the data on a regular schedule. Without a
recent backup, you have no chance of recovery after a catastrophe (disk failure, fire, mistakenly dropping a
critical table, etc). The backup and recovery mechanisms available in PostgreSQL are discussed at length
in Chapter 9.
The other main category of maintenance task is periodic “vacuuming” of the database. This activity is
discussed in Section 8.2.
Something else that might need periodic attention is log file management. This is discussed in Section 8.4.
PostgreSQL is low-maintenance compared to some other database products. Nonetheless, appropriate
attention to these tasks will go far towards ensuring a pleasant and productive experience with the system.
8.2. Routine Vacuuming
PostgreSQL’s VACUUM command must be run on a regular basis for several reasons:
1. To recover disk space occupied by updated or deleted rows.
2. To update data statistics used by the PostgreSQL query planner.
3. To protect against loss of very old data due to transaction ID wraparound.
The frequency and scope of VACUUMs performed for each of these reasons will vary depending on the
needs of each installation. Therefore, database administrators must understand these issues and develop
an appropriate maintenance strategy. This section concentrates on explaining the high-level issues; for
details about command syntax and so on, see the VACUUM command reference page.
Beginning in PostgreSQL 7.2, the standard form of VACUUM can run in parallel with normal database
operations (selects, inserts, updates, deletes, but not changes to table schemas). Routine vacuuming is
therefore not nearly as intrusive as it was in prior releases, and it’s not as critical to try to schedule it at
low-usage times of day.
8.2.1. Recovering disk space
In normal PostgreSQL operation, an UPDATE or DELETE of a row does not immediately remove the old
tuple (version of the row). This approach is necessary to gain the benefits of multiversion concurrency
control (see the PostgreSQL User’s Guide): the tuple must not be deleted while it is still potentially
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Chapter 8. Routine Database Maintenance Tasks
visible to other transactions. But eventually, an outdated or deleted tuple is no longer of interest to any
transaction. The space it occupies must be reclaimed for reuse by new tuples, to avoid infinite growth of
disk space requirements. This is done by running VACUUM.
Clearly, a table that receives frequent updates or deletes will need to be vacuumed more often than tables
that are seldom updated. It may be useful to set up periodic cron tasks that vacuum only selected tables,
skipping tables that are known not to change often. This is only likely to be helpful if you have both large
heavily-updated tables and large seldom-updated tables --- the extra cost of vacuuming a small table isn’t
enough to be worth worrying about.
The standard form of VACUUM is best used with the goal of maintaining a fairly level steady-state usage
of disk space. The standard form finds old tuples and makes their space available for re-use within the
table, but it does not try very hard to shorten the table file and return disk space to the operating system.
If you need to return disk space to the operating system you can use VACUUM FULL --- but what’s the
point of releasing disk space that will only have to be allocated again soon? Moderately frequent standard
VACUUMs are a better approach than infrequent VACUUM FULLs for maintaining heavily-updated tables.
Recommended practice for most sites is to schedule a database-wide VACUUM once a day at a low-usage
time of day, supplemented by more frequent vacuuming of heavily-updated tables if necessary. (If you
have multiple databases in an installation, don’t forget to vacuum each one; the vacuumdb script may be
helpful.) Use plain VACUUM, not VACUUM FULL, for routine vacuuming for space recovery.
VACUUM FULL is recommended for cases where you know you have deleted the majority of tuples in a
table, so that the steady-state size of the table can be shrunk substantially with VACUUM FULL’s more
aggressive approach.
If you have a table whose contents are deleted completely every so often, consider doing it with TRUNCATE
rather than using DELETE followed by VACUUM.
8.2.2. Updating planner statistics
The PostgreSQL query planner relies on statistical information about the contents of tables in order to
generate good plans for queries. These statistics are gathered by the ANALYZE command, which can be
invoked by itself or as an optional step in VACUUM. It is important to have reasonably accurate statistics,
otherwise poor choices of plans may degrade database performance.
As with vacuuming for space recovery, frequent updates of statistics are more useful for heavily-updated
tables than for seldom-updated ones. But even for a heavily-updated table, there may be no need for
statistics updates if the statistical distribution of the data is not changing much. A simple rule of thumb
is to think about how much the minimum and maximum values of the columns in the table change.
For example, a timestamp column that contains the time of row update will have a constantly-increasing
maximum value as rows are added and updated; such a column will probably need more frequent statistics
updates than, say, a column containing URLs for pages accessed on a website. The URL column may
receive changes just as often, but the statistical distribution of its values probably changes relatively slowly.
It is possible to run ANALYZE on specific tables and even just specific columns of a table, so the flexibility
exists to update some statistics more frequently than others if your application requires it. In practice,
however, the usefulness of this feature is doubtful. Beginning in PostgreSQL 7.2, ANALYZE is a fairly fast
operation even on large tables, because it uses a statistical random sampling of the rows of a table rather
than reading every single row. So it’s probably much simpler to just run it over the whole database every
so often.
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Chapter 8. Routine Database Maintenance Tasks
Tip: Although per-column tweaking of ANALYZE frequency may not be very productive, you may well
find it worthwhile to do per-column adjustment of the level of detail of the statistics collected by AN-
ALYZE. Columns that are heavily used in WHERE clauses and have highly irregular data distributions
may require a finer-grain data histogram than other columns. See ALTER TABLE SET STATISTICS.
Recommended practice for most sites is to schedule a database-wide ANALYZE once a day at a low-usage
time of day; this can usefully be combined with a nightly VACUUM. However, sites with relatively slowly
changing table statistics may find that this is overkill, and that less-frequent ANALYZE runs are sufficient.
8.2.3. Preventing transaction ID wraparound failures
PostgreSQL’s MVCC transaction semantics depend on being able to compare transaction ID (XID) num-
bers: a tuple with an insertion XID newer than the current transaction’s XID is “in the future” and should
not be visible to the current transaction. But since transaction IDs have limited size (32 bits at this writ-
ing) an installation that runs for a long time (more than 4 billion transactions) will suffer transaction ID
wraparound: the XID counter wraps around to zero, and all of a sudden transactions that were in the past
appear to be in the future --- which means their outputs become invisible. In short, catastrophic data loss.
(Actually the data is still there, but that’s cold comfort if you can’t get at it.)
Prior to PostgreSQL 7.2, the only defense against XID wraparound was to re-initdb at least every 4
billion transactions. This of course was not very satisfactory for high-traffic sites, so a better solution has
been devised. The new approach allows an installation to remain up indefinitely, without initdb or any
sort of restart. The price is this maintenance requirement: every table in the database must be vacuumed
at least once every billion transactions.
In practice this isn’t an onerous requirement, but since the consequences of failing to meet it can be
complete data loss (not just wasted disk space or slow performance), some special provisions have been
made to help database administrators keep track of the time since the last VACUUM. The remainder of this
section gives the details.
The new approach to XID comparison distinguishes two special XIDs, numbers 1 and 2 (BootstrapXID
and FrozenXID). These two XIDs are always considered older than every normal XID. Normal XIDs
(those greater than 2) are compared using modulo-2
31
arithmetic. This means that for every normal XID,
there are two billion XIDs that are “older” and two billion that are “newer”; another way to say it is that the
normal XID space is circular with no endpoint. Therefore, once a tuple has been created with a particular
normal XID, the tuple will appear to be “in the past” for the next two billion transactions, no matter
which normal XID we are talking about. If the tuple still exists after more than two billion transactions,
it will suddenly appear to be in the future. To prevent data loss, old tuples must be reassigned the XID
FrozenXID sometime before they reach the two-billion-transactions-old mark. Once they are assigned
this special XID, they will appear to be “in the past” to all normal transactions regardless of wraparound
issues, and so such tuples will be good until deleted, no matter how long that is. This reassignment of XID
is handled by VACUUM.
VACUUM’s normal policy is to reassign FrozenXID to any tuple with a normal XID more than one billion
transactions in the past. This policy preserves the original insertion XID until it is not likely to be of
interest anymore (in fact, most tuples will probably live and die without ever being “frozen”). With this
policy, the maximum safe interval between VACUUMs of any table is exactly one billion transactions: if you
wait longer, it’s possible that a tuple that was not quite old enough to be reassigned last time is now more
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Chapter 8. Routine Database Maintenance Tasks
than two billion transactions old and has wrapped around into the future --- i.e., is lost to you. (Of course,
it’ll reappear after another two billion transactions, but that’s no help.)
Since periodic VACUUMs are needed anyway for the reasons described earlier, it’s unlikely that any table
would not be vacuumed for as long as a billion transactions. But to help administrators ensure this con-
straint is met, VACUUM stores transaction ID statistics in the system table pg_database. In particular, the
datfrozenxid field of a database’s pg_database row is updated at the completion of any database-
wide vacuum operation (i.e., VACUUM that does not name a specific table). The value stored in this field is
the freeze cutoff XID that was used by that VACUUM command. All normal XIDs older than this cutoff XID
are guaranteed to have been replaced by FrozenXID within that database. A convenient way to examine
this information is to execute the query
SELECT datname, age(datfrozenxid) FROM pg_database;
The age column measures the number of transactions from the cutoff XID to the current transaction’s
XID.
With the standard freezing policy, the age column will start at one billion for a freshly-vacuumed database.
When the age approaches two billion, the database must be vacuumed again to avoid risk of wraparound
failures. Recommended practice is to vacuum each database at least once every half-a-billion (500 million)
transactions, so as to provide plenty of safety margin. To help meet this rule, each database-wide VACUUM
automatically delivers a warning if there are any pg_database entries showing an age of more than 1.5
billion transactions, for example:
play=# vacuum;
WARNING: Some databases have not been vacuumed in 1613770184 transactions.
Better vacuum them within 533713463 transactions,
or you may have a wraparound failure.
VACUUM
VACUUM with the FREEZE option uses a more aggressive freezing policy: tuples are frozen if they are old
enough to be considered good by all open transactions. In particular, if a VACUUM FREEZE is performed in
an otherwise-idle database, it is guaranteed that all tuples in that database will be frozen. Hence, as long
as the database is not modified in any way, it will not need subsequent vacuuming to avoid transaction ID
wraparound problems. This technique is used by initdb to prepare the template0 database. It should
also be used to prepare any user-created databases that are to be marked datallowconn = false in
pg_database, since there isn’t any convenient way to vacuum a database that you can’t connect to. Note
that VACUUM’s automatic warning message about unvacuumed databases will ignore pg_database entries
with datallowconn = false, so as to avoid giving false warnings about these databases; therefore it’s
up to you to ensure that such databases are frozen correctly.
8.3. Routine Reindexing
PostgreSQL is unable to reuse B-tree index pages in certain cases. The problem is that if indexed rows are
deleted, those index pages can only be reused by rows with similar values. For example, if indexed rows
are deleted and newly inserted/updated rows have much higher values, the new rows can’t use the index
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Chapter 8. Routine Database Maintenance Tasks
space made available by the deleted rows. Instead, such new rows must be placed on new index pages. In
such cases, disk space used by the index will grow indefinitely, even if VACUUM is run frequently.
As a solution, you can use the REINDEX command periodically to discard pages used by deleted rows.
There is also contrib/reindexdb which can reindex an entire database.
8.4. Log File Maintenance
It’s a good idea to save the database server’s log output somewhere, rather than just routing it to
/dev/null. The log output is invaluable when it comes time to diagnose problems. However, the
log output tends to be voluminous (especially at higher debug levels) and you won’t want to save it
indefinitely. You need to “rotate” the log files so that new log files are started and old ones thrown away
every so often.
If you simply direct the postmaster’s stderr into a file, the only way to truncate the log file is to stop and
restart the postmaster. This may be OK for development setups but you won’t want to run a production
server that way.
The simplest production-grade approach to managing log output is to send it all to syslog and let syslog
deal with file rotation. To do this, set syslog to 2 (log to syslog only) in postgresql.conf. Then you
can send a SIGHUP signal to the syslog daemon whenever you want to force it to start writing a new log
file.
On many systems, however, syslog is not very reliable, particularly with large log messages; it may trun-
cate or drop messages just when you need them the most. You may find it more useful to pipe the postmas-
ter’s stderr to some type of log rotation script. If you start the postmaster with pg_ctl, then the postmaster’s
stderr is already redirected to stdout, so you just need a pipe command:
pg_ctl start | logrotate
The PostgreSQL distribution doesn’t include a suitable log rotation program, but there are many available
on the net; one is included in the Apache distribution, for example.
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Chapter 9. Backup and Restore
As everything that contains valuable data, PostgreSQL databases should be backed up regularly. While the
procedure is essentially simple, it is important to have a basic understanding of the underlying techniques
and assumptions.
There are two fundamentally different approaches to backing up PostgreSQL data:
• SQL dump
• File system level backup
9.1. SQL Dump
The idea behind the SQL-dump method is to generate a text file with SQL commands that, when fed back
to the server, will recreate the database in the same state as it was at the time of the dump. PostgreSQL
provides the utility program pg_dump for this purpose. The basic usage of this command is:
pg_dump dbname > outfile
As you see, pg_dump writes its results to the standard output. We will see below how this can be useful.
pg_dump is a regular PostgreSQL client application (albeit a particularly clever one). This means that you
can do this backup procedure from any remote host that has access to the database. But remember that
pg_dump does not operate with special permissions. In particular, you must have read access to all tables
that you want to back up, so in practice you almost always have to be a database superuser.
To specify which database server pg_dump should contact, use the command line options -h host and
-p port. The default host is the local host or whatever your PGHOST environment variable specifies. Sim-
ilarly, the default port is indicated by the PGPORT environment variable or, failing that, by the compiled-in
default. (Conveniently, the server will normally have the same compiled-in default.)
As any other PostgreSQL client application, pg_dump will by default connect with the database user name
that is equal to the current operating system user name. To override this, either specify the -U option or set
the environment variable PGUSER. Remember that pg_dump connections are subject to the normal client
authentication mechanisms (which are described in Chapter 6).
Dumps created by pg_dump are internally consistent, that is, updates to the database while pg_dump is
running will not be in the dump. pg_dump does not block other operations on the database while it is
working. (Exceptions are those operations that need to operate with an exclusive lock, such as VACUUM
FULL.)
Important: When your database schema relies on OIDs (for instance as foreign keys) you must
instruct pg_dump to dump the OIDs as well. To do this, use the -o command line option. “Large
objects” are not dumped by default, either. See pg_dump’s command reference page if you use large
objects.
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9.1.1. Restoring the dump
The text files created by pg_dump are intended to be read in by the psql program. The general command
form to restore a dump is
psql dbname < infile
where infile is what you used as outfile for the pg_dump command. The database dbname will
not be created by this command, you must create it yourself from template0 before executing psql (e.g.,
with createdb -T template0 dbname). psql supports similar options to pg_dump for controlling the
database server location and the user names. See its reference page for more information.
If the objects in the original database were owned by different users, then the dump will instruct psql to
connect as each affected user in turn and then create the relevant objects. This way the original ownership
is preserved. This also means, however, that all these users must already exist, and furthermore that you
must be allowed to connect as each of them. It might therefore be necessary to temporarily relax the client
authentication settings.
The ability of pg_dump and psql to write to or read from pipes makes it possible to dump a database
directly from one server to another, for example
pg_dump -h host1 dbname | psql -h host2 dbname
Important: The dumps produced by pg_dump are relative to template0. This means that any lan-
guages, procedures, etc. added to template1 will also be dumped by pg_dump. As a result, when
restoring, if you are using a customized template1, you must create the empty database from tem-
plate0, as in the example above.
9.1.2. Using pg_dumpall
The above mechanism is cumbersome and inappropriate when backing up an entire database cluster. For
this reason the pg_dumpall program is provided. pg_dumpall backs up each database in a given cluster
and also makes sure that the state of global data such as users and groups is preserved. The call sequence
for pg_dumpall is simply
pg_dumpall > outfile
The resulting dumps can be restored with psql as described above. But in this case it is definitely necessary
that you have database superuser access, as that is required to restore the user and group information.
9.1.3. Large Databases
Acknowledgement: Originally written by Hannu Krosing (<[email protected]>) on 1999-06-19
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Since PostgreSQL allows tables larger than the maximum file size on your system, it can be problematic
to dump the table to a file, since the resulting file will likely be larger than the maximum size allowed
by your system. As pg_dump writes to the standard output, you can just use standard *nix tools to work
around this possible problem.
Use compressed dumps. Use your favorite compression program, for example gzip.
pg_dump dbname | gzip > filename.gz
Reload with
createdb dbname
gunzip -c filename.gz | psql dbname
or
cat filename.gz | gunzip | psql dbname
Use split. This allows you to split the output into pieces that are acceptable in size to the underlying file
system. For example, to make chunks of 1 megabyte:
pg_dump dbname | split -b 1m - filename
Reload with
createdb dbname
cat filename* | psql dbname
Use the custom dump format. If PostgreSQL was built on a system with the zlib compression library
installed, the custom dump format will compress data as it writes it to the output file. For large databases,
this will produce similar dump sizes to using gzip, but has the added advantage that the tables can be
restored selectively. The following command dumps a database using the custom dump format:
pg_dump -Fc dbname > filename
See the pg_dump and pg_restore reference pages for details.
9.1.4. Caveats
pg_dump (and by implication pg_dumpall) has a few limitations which stem from the difficulty to recon-
struct certain information from the system catalogs.
Specifically, the order in which pg_dump writes the objects is not very sophisticated. This can lead to
problems for example when functions are used as column default values. The only answer is to manually
reorder the dump. If you created circular dependencies in your schema then you will have more work to
do.
For reasons of backward compatibility, pg_dump does not dump large objects by default. To dump large
objects you must use either the custom or the TAR output format, and use the -b option in pg_dump. See
the reference pages for details. The directory contrib/pg_dumplo of the PostgreSQL source tree also
contains a program that can dump large objects.
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Please familiarize yourself with the pg_dump reference page.
9.2. File system level backup
An alternative backup strategy is to directly copy the files that PostgreSQL uses to store the data in the
database. In Section 3.2 it is explained where these files are located, but you have probably found them
already if you are interested in this method. You can use whatever method you prefer for doing usual file
system backups, for example
tar -cf backup.tar /usr/local/pgsql/data
There are two restrictions, however, which make this method impractical, or at least inferior to the
pg_dump method:
1. The database server must be shut down in order to get a usable backup. Half-way measures such as
disallowing all connections will not work as there is always some buffering going on. For this reason
it is also not advisable to trust file systems that claim to support “consistent snapshots”. Information
about stopping the server can be found in Section 3.6.
Needless to say that you also need to shut down the server before restoring the data.
2. If you have dug into the details of the file system layout you may be tempted to try to back up or
restore only certain individual tables or databases from their respective files or directories. This will
not work because the information contained in these files contains only half the truth. The other half
is in the commit log files pg_clog/*, which contain the commit status of all transactions. A table
file is only usable with this information. Of course it is also impossible to restore only a table and the
associated pg_clog data because that will render all other tables in the database cluster useless.
Also note that the file system backup will not necessarily be smaller than an SQL dump. On the contrary,
it will most likely be larger. (pg_dump does not need to dump the contents of indexes for example, just
the commands to recreate them.)
9.3. Migration between releases
As a general rule, the internal data storage format is subject to change between releases of PostgreSQL.
This does not apply to different “patch levels”, these always have compatible storage formats. For ex-
ample, releases 7.0.1, 7.1.2, and 7.2 are not compatible, whereas 7.1.1 and 7.1.2 are. When you update
between compatible versions, then you can simply reuse the data area in disk by the new executables.
Otherwise you need to “back up” your data and “restore” it on the new server, using pg_dump. (There are
checks in place that prevent you from doing the wrong thing, so no harm can be done by confusing these
things.) The precise installation procedure is not subject of this section, these details are in Chapter 1.
The least downtime can be achieved by installing the new server in a different directory and running both
the old and the new servers in parallel, on different ports. Then you can use something like
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Chapter 9. Backup and Restore
pg_dumpall -p 5432 | psql -d template1 -p 6543
to transfer your data, or use an intermediate file if you want. Then you can shut down the old server and
start the new server at the port the old one was running at. You should make sure that the database is
not updated after you run pg_dumpall, otherwise you will obviously lose that data. See Chapter 6 for
information on how to prohibit access. In practice you probably want to test your client applications on
the new setup before switching over.
If you cannot or do not want to run two servers in parallel you can do the back up step before installing
the new version, bring down the server, move the old version out of the way, install the new version, start
the new server, restore the data. For example:
pg_dumpall > backup
pg_ctl stop
mv /usr/local/pgsql /usr/local/pgsql.old
cd /usr/src/postgresql-7.3.2
gmake install
initdb -D /usr/local/pgsql/data
postmaster -D /usr/local/pgsql/data
psql template1 < backup
See Chapter 3 about ways to start and stop the server and other details. The installation instructions will
advise you of strategic places to perform these steps.
Note: When you “move the old installation out of the way” it is no longer perfectly usable. Some parts
of the installation contain information about where the other parts are located. This is usually not a
big problem but if you plan on using two installations in parallel for a while you should assign them
different installation directories at build time.
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Chapter 10. Monitoring Database Activity
A database administrator frequently wonders, “What is the system doing right now?” This chapter dis-
cusses how to find that out.
Several tools are available for monitoring database activity and analyzing performance. Most of this chap-
ter is devoted to describing PostgreSQL’s statistics collector, but one should not neglect regular Unix
monitoring programs such as ps and top. Also, once one has identified a poorly-performing query, fur-
ther investigation may be needed using PostgreSQL’s EXPLAIN command. The PostgreSQL User’s Guide
discusses EXPLAIN and other methods for understanding the behavior of an individual query.
10.1. Standard Unix Tools
On most platforms, PostgreSQL modifies its command title as reported by ps, so that individual server
processes can readily be identified. A sample display is
$ ps auxww | grep ^postgres
postgres 960 0.0 1.1 6104 1480 pts/1 SN 13:17 0:00 postmaster -
i
postgres 963 0.0 1.1 7084 1472 pts/1 SN 13:17 0:00 postgres: stats buffer pro-
cess
postgres 965 0.0 1.1 6152 1512 pts/1 SN 13:17 0:00 postgres: stats col-
lector process
postgres 998 0.0 2.3 6532 2992 pts/1 SN 13:18 0:00 postgres: tgl run-
bug 127.0.0.1 idle
postgres 1003 0.0 2.4 6532 3128 pts/1 SN 13:19 0:00 postgres: tgl re-
gression [local] SELECT waiting
postgres 1016 0.1 2.4 6532 3080 pts/1 SN 13:19 0:00 postgres: tgl re-
gression [local] idle in transaction
(The appropriate invocation of ps varies across different platforms, as do the details of what is shown.
This example is from a recent Linux system.) The first process listed here is the postmaster, the master
server process. The command arguments shown for it are the same ones given when it was launched.
The next two processes implement the statistics collector, which will be described in detail in the next
section. (These will not be present if you have set the system not to start the statistics collector.) Each
of the remaining processes is a server process handling one client connection. Each such process sets its
command line display in the form
postgres: user database host activity
The user, database, and connection source host items remain the same for the life of the client connection,
but the activity indicator changes. The activity may be idle (i.e., waiting for a client command), idle
in transaction (waiting for client inside a BEGIN block), or a command type name such as SELECT.
Also, waiting is attached if the server is presently waiting on a lock held by another server process. In
the above example we can infer that process 1003 is waiting for process 1016 to complete its transaction
and thereby release some lock or other.
Tip: Solaris requires special handling. You must use /usr/ucb/ps, rather than /bin/ps. You also
must use two w flags, not just one. In addition, your original invocation of the postmaster must have a
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shorter ps status display than that provided by each backend. If you fail to do all three things, the ps
output for each backend will be the original postmaster command line.
10.2. Statistics Collector
PostgreSQL’s statistics collector is a subsystem that supports collection and reporting of information
about server activity. Presently, the collector can count accesses to tables and indexes in both disk-block
and individual-row terms. It also supports determining the exact query currently being executed by other
server processes.
10.2.1. Statistics Collection Configuration
Since collection of statistics adds some overhead to query execution, the system can be configured to
collect or not collect information. This is controlled by configuration variables that are normally set in
postgresql.conf (see Section 3.4 for details about setting configuration variables).
The variable STATS_START_COLLECTOR must be set to true for the statistics collector to be launched
at all. This is the default and recommended setting, but it may be turned off if you have no interest in
statistics and want to squeeze out every last drop of overhead. (The savings is likely to be small, however.)
Note that this option cannot be changed while the server is running.
The variables STATS_COMMAND_STRING, STATS_BLOCK_LEVEL, and STATS_ROW_LEVEL control how
much information is actually sent to the collector, and thus determine how much run-time overhead occurs.
These respectively determine whether a server process sends its current command string, disk-block-
level access statistics, and row-level access statistics to the collector. Normally these variables are set in
postgresql.conf so that they apply to all server processes, but it is possible to turn them on or off in
individual server processes using the SET command. (To prevent ordinary users from hiding their activity
from the administrator, only superusers are allowed to change these variables with SET.)
Important: Since the variables STATS_COMMAND_STRING, STATS_BLOCK_LEVEL, and
STATS_ROW_LEVEL default to false, no statistics are actually collected in the default configuration.
You must turn one or more of them on before you will get useful results from the statistical display
functions.
10.2.2. Viewing Collected Statistics
Several predefined views are available to show the results of statistics collection, listed in Table 10-1.
Alternatively, one can build custom views using the underlying statistics functions.
When using the statistics to monitor current activity, it is important to realize that the information does
not update instantaneously. Each individual server process transmits new access counts to the collector
just before waiting for another client command; so a query still in progress does not affect the displayed
totals. Also, the collector itself emits new totals at most once per pgstat_stat_interval milliseconds
(500 by default). So the displayed totals lag behind actual activity.
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Chapter 10. Monitoring Database Activity
Another important point is that when a server process is asked to display any of these statistics, it first
fetches the most recent totals emitted by the collector process. It then continues to use this snapshot for all
statistical views and functions until the end of its current transaction. So the statistics will appear not to
change as long as you continue the current transaction. This is a feature, not a bug, because it allows you
to perform several queries on the statistics and correlate the results without worrying that the numbers are
changing underneath you. But if you want to see new results with each query, be sure to do the queries
outside any transaction block.
Table 10-1. Standard Statistics Views
View Name Description
pg_stat_activity One row per server process, showing process ID,
database, user, and current query. The current query
column is only available to superusers; for others it
reads as null. (Note that because of the collector’s
reporting delay, current query will only be
up-to-date for long-running queries.)
pg_stat_database One row per database, showing number of active
backends, total transactions committed and total
rolled back in that database, total disk blocks read,
and total number of buffer hits (i.e., block read
requests avoided by finding the block already in
buffer cache).
pg_stat_all_tables For each table in the current database, total
numbers of sequential and index scans, total
numbers of tuples returned by each type of scan,
and totals of tuple insertions, updates, and deletes.
pg_stat_sys_tables Same as pg_stat_all_tables, except that only
system tables are shown.
pg_stat_user_tables Same as pg_stat_all_tables, except that only
user tables are shown.
pg_stat_all_indexes For each index in the current database, the total
number of index scans that have used that index,
the number of index tuples read, and the number of
successfully fetched heap tuples. (This may be less
when there are index entries pointing to expired
heap tuples.)
pg_stat_sys_indexes Same as pg_stat_all_indexes, except that only
indexes on system tables are shown.
pg_stat_user_indexes Same as pg_stat_all_indexes, except that only
indexes on user tables are shown.
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View Name Description
pg_statio_all_tables For each table in the current database, the total
number of disk blocks read from that table, the
number of buffer hits, the numbers of disk blocks
read and buffer hits in all the indexes of that table,
the numbers of disk blocks read and buffer hits
from the table’s auxiliary TOAST table (if any),
and the numbers of disk blocks read and buffer hits
for the TOAST table’s index.
pg_statio_sys_tables Same as pg_statio_all_tables, except that
only system tables are shown.
pg_statio_user_tables Same as pg_statio_all_tables, except that
only user tables are shown.
pg_statio_all_indexes For each index in the current database, the numbers
of disk blocks read and buffer hits in that index.
pg_statio_sys_indexes Same as pg_statio_all_indexes, except that
only indexes on system tables are shown.
pg_statio_user_indexes Same as pg_statio_all_indexes, except that
only indexes on user tables are shown.
pg_statio_all_sequences For each sequence object in the current database,
the numbers of disk blocks read and buffer hits in
that sequence.
pg_statio_sys_sequences Same as pg_statio_all_sequences, except
that only system sequences are shown. (Presently,
no system sequences are defined, so this view is
always empty.)
pg_statio_user_sequences Same as pg_statio_all_sequences, except
that only user sequences are shown.
The per-index statistics are particularly useful to determine which indexes are being used and how effec-
tive they are.
The pg_statio_ views are primarily useful to determine the effectiveness of the buffer cache. When the
number of actual disk reads is much smaller than the number of buffer hits, then the cache is satisfying
most read requests without invoking a kernel call.
Other ways of looking at the statistics can be set up by writing queries that use the same underlying
statistics access functions as these standard views do. These functions are listed in Table 10-2. The per-
database access functions accept a database OID to identify which database to report on. The per-table and
per-index functions accept a table or index OID (note that only tables and indexes in the current database
can be seen with these functions). The per-backend access functions accept a backend ID number, which
ranges from one to the number of currently active backends.
Table 10-2. Statistics Access Functions
Function Return Type Description
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Function Return Type Description
pg_stat_get_db_numbackends(oid)integer Number of active backends in
database
pg_stat_get_db_xact_commit(oid)bigint Transactions committed in
database
pg_stat_get_db_xact_rollback(oid)bigint Transactions rolled back in
database
pg_stat_get_db_blocks_fetched(oid)bigint Number of disk block fetch
requests for database
pg_stat_get_db_blocks_hit(oid)bigint Number of disk block requests
found in cache for database
pg_stat_get_numscans(oid) bigint Number of sequential scans done
when argument is a table, or
number of index scans done when
argument is an index
pg_stat_get_tuples_returned(oid)bigint Number of tuples read by
sequential scans when argument
is a table, or number of index
tuples read when argument is an
index
pg_stat_get_tuples_fetched(oid)bigint Number of valid (unexpired)
table tuples fetched by sequential
scans when argument is a table, or
fetched by index scans using this
index when argument is an index
pg_stat_get_tuples_inserted(oid)bigint Number of tuples inserted into
table
pg_stat_get_tuples_updated(oid)bigint Number of tuples updated in
table
pg_stat_get_tuples_deleted(oid)bigint Number of tuples deleted from
table
pg_stat_get_blocks_fetched(oid)bigint Number of disk block fetch
requests for table or index
pg_stat_get_blocks_hit(oid)bigint Number of disk block requests
found in cache for table or index
pg_stat_get_backend_idset()set of integer Set of currently active backend
IDs (from 1 to N where N is the
number of active backends). See
usage example below.
pg_backend_pid() integer Process ID of the attached
backend
pg_stat_get_backend_pid(integer)integer Process ID of all backend
processes
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Function Return Type Description
pg_stat_get_backend_dbid(integer)oid Database ID of backend process
pg_stat_get_backend_userid(integer)oid User ID of backend process
pg_stat_get_backend_activity(integer)text Current query of backend process
(NULL if caller is not superuser)
pg_stat_reset() boolean Reset all currently collected
statistics.
Note: Blocks_fetched minus blocks_hit gives the number of kernel read() calls issued for the ta-
ble, index, or database; but the actual number of physical reads is usually lower due to kernel-level
buffering.
The function pg_stat_get_backend_idset provides a convenient way to generate one row for each
active backend. For example, to show the PIDs and current queries of all backends:
SELECT pg_stat_get_backend_pid(S.backendid) AS procpid,
pg_stat_get_backend_activity(S.backendid) AS current_query
FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS S;
10.3. Viewing Locks
Another useful tool for monitoring database activity is the pg_locks system catalog. This allows the
database administrator to view information about the outstanding locks in the lock manager. For example,
this capability can be used to:
• View all the locks currently outstanding, all the locks on relations in a particular database, all the locks
on a particular relation, or all the locks held by a particular PostgreSQL session.
• View the relation in the current database with the most ungranted locks (which might be a source of
contention among database clients).
• Determine the effect of lock contention on overall database performance, as well as the extent to which
contention varies with overall database traffic.
For more information on locking and managing concurrency with PostgreSQL, refer to the PostgreSQL
User’s Guide.
Note: When the pg_locks view is accessed, the internal lock manager data structures are momentar-
ily locked, and a copy is made for the view to display. This ensures that the view produces a consistent
set of results, while not blocking normal lock manager operations longer than necessary. Nonetheless
there could be some impact on database performance if this view is examined often.
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Table 10-3 shows the definition of the pg_locks columns. The pg_locks view contains one row per
lockable object and requested lock mode. Thus, the same lockable object may appear many times, if
multiple transactions are holding or waiting for locks on it. A lockable object is either a relation or a
transaction ID. (Note that this view includes only table-level locks, not row-level ones. If a transaction
is waiting for a row-level lock, it will appear in the view as waiting for the transaction ID of the current
holder of that row lock.)
Table 10-3. Lock Status System View
Column Name Type Description
relation oid The OID of the locked relation,
or null if the lockable object is a
transaction ID. This column can
be joined with the pg_class
system catalog to get more
information on the locked
relation. Note however that this
will only work for relations in the
current database (those for which
the database column is either
the current database’s OID or
zero).
database oid The OID of the database in
which the locked relation exists,
or null if the lockable object is a
transaction ID. If the lock is on a
globally-shared table, this field
will be zero. This column can be
joined with the pg_database
system catalog to get more
information on the locked object’s
database.
transaction xid The ID of a transaction, or null if
the lockable object is a relation.
Every transaction holds an
exclusive lock on its transaction
ID for its entire duration. If one
transaction finds it necessary to
wait specifically for another
transaction, it does so by
attempting to acquire share lock
on the other transaction ID. That
will succeed only when the other
transaction terminates and
releases its locks.
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Column Name Type Description
pid integer The process ID of the
PostgreSQL backend belonging
to the session that has acquired or
is attempting to acquire the lock.
If you have enabled the statistics
collector, this column can be
joined with the
pg_stat_activity view to get
more information on the backend
holding or waiting to hold the
lock.
mode text The mode of the requested or
held lock on the lockable object.
For more information on the
different lock modes available in
PostgreSQL, refer to the
PostgreSQL User’s Guide.
isgranted boolean True if this lock has been granted
(is held by this session). False
indicates that this session is
currently waiting to acquire this
lock, which implies that some
other session is holding a
conflicting lock mode on the same
lockable object. This backend will
sleep until the other lock is
released (or a deadlock situation
is detected). A single backend can
be waiting to acquire at most one
lock at a time.
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Chapter 11. Monitoring Disk Usage
This chapter discusses how to monitor the disk usage of a PostgreSQL database system. In the current
release, the database administrator does not have much control over the on-disk storage layout, so this
chapter is mostly informative and can give you some ideas how to manage the disk usage with operating
system tools.
11.1. Determining Disk Usage
Each table has a primary heap disk file where most of the data is stored. To store long column val-
ues, there is also a TOAST file associated with the table, named based on the table’s OID (actually
pg_class.relfilenode), and an index on the TOAST table. There also may be indexes associated
with the base table.
You can monitor disk space from three places: from psql using VACUUMinformation, from psql using con-
trib/dbsize, and from the command line using contrib/oid2name. Using psql on a recently vacuumed
(or analyzed) database, you can issue queries to see the disk usage of any table:
play=# SELECT relfilenode, relpages
play-# FROM pg_class
play-# WHERE relname = ’customer’;
relfilenode | relpages
-------------+----------
16806 | 60
(1 row)
Each page is typically 8 kilobytes. (Remember, relpages is only updated by VACUUM and ANALYZE.) To
show the space used by TOAST tables, use a query based on the heap relfilenode shown above:
play=# SELECT relname, relpages
play-# FROM pg_class
play-# WHERE relname = ’pg_toast_16806’ OR
play-# relname = ’pg_toast_16806_index’
play-# ORDER BY relname;
relname | relpages
----------------------+----------
pg_toast_16806 | 0
pg_toast_16806_index | 1
You can easily display index usage too:
play=# SELECT c2.relname, c2.relpages
play-# FROM pg_class c, pg_class c2, pg_index i
play-# WHERE c.relname = ’customer’ AND
play-# c.oid = i.indrelid AND
play-# c2.oid = i.indexrelid
play-# ORDER BY c2.relname;
relname | relpages
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Chapter 11. Monitoring Disk Usage
----------------------+----------
customer_id_indexdex | 26
It is easy to find your largest files using psql:
play=# SELECT relname, relpages
play-# FROM pg_class
play-# ORDER BY relpages DESC;
relname | relpages
----------------------+----------
bigtable | 3290
customer | 3144
contrib/dbsize loads functions into your database that allow you to find the size of a table or database
from inside psql without the need for VACUUM/ANALYZE.
You can also use contrib/oid2name to show disk usage. See README.oid2name for examples. It
includes a script that shows disk usage for each database.
11.2. Disk Full Failure
The most important disk monitoring task of a database administrator is to make sure the disk doesn’t grow
full. A filled data disk may result in subsequent corruption of database indexes, but not of the fundamental
data tables. If the WAL files are on the same disk (as is the case for a default configuration) then a filled
disk during database initialization may result in corrupted or incomplete WAL files. This failure condition
is detected and the database server will refuse to start up.
If you cannot free up additional space on the disk by deleting other things you can move some of the
database files to other file systems and create a symlink from the original location. But note that pg_dump
cannot save the location layout information of such a setup; a restore would put everything back in one
place. To avoid running out of disk space, you can place the WAL files or individual databases in other
locations while creating them. See the initdb documentation and Section 5.5 for more information.
Tip: Some file systems perform badly when they are almost full, so do not wait until the disk is full to
take action.
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Chapter 12. Write-Ahead Logging (WAL)
Author: Vadim Mikheev and Oliver Elphick
12.1. General Description
Write Ahead Logging (WAL) is a standard approach to transaction logging. Its detailed description may
be found in most (if not all) books about transaction processing. Briefly, WAL’s central concept is that
changes to data files (where tables and indexes reside) must be written only after those changes have
been logged - that is, when log records have been flushed to permanent storage. When we follow this
procedure, we do not need to flush data pages to disk on every transaction commit, because we know that
in the event of a crash we will be able to recover the database using the log: any changes that have not
been applied to the data pages will first be redone from the log records (this is roll-forward recovery, also
known as REDO) and then changes made by uncommitted transactions will be removed from the data
pages (roll-backward recovery - UNDO).
12.1.1. Immediate Benefits of WAL
The first obvious benefit of using WAL is a significantly reduced number of disk writes, since only the log
file needs to be flushed to disk at the time of transaction commit; in multiuser environments, commits of
many transactions may be accomplished with a single fsync() of the log file. Furthermore, the log file
is written sequentially, and so the cost of syncing the log is much less than the cost of flushing the data
pages.
The next benefit is consistency of the data pages. The truth is that, before WAL, PostgreSQL was never
able to guarantee consistency in the case of a crash. Before WAL, any crash during writing could result
in:
1. index tuples pointing to nonexistent table rows
2. index tuples lost in split operations
3. totally corrupted table or index page content, because of partially written data pages
Problems with indexes (problems 1 and 2) could possibly have been fixed by additional fsync() calls,
but it is not obvious how to handle the last case without WAL; WAL saves the entire data page content in
the log if that is required to ensure page consistency for after-crash recovery.
12.1.2. Future Benefits
UNDO operation is not implemented. This means that changes made by aborted transactions will still
occupy disk space and that we still need a permanent pg_clog file to hold the status of transactions, since
we are not able to re-use transaction identifiers. Once UNDO is implemented, pg_clog will no longer be
required to be permanent; it will be possible to remove pg_clog at shutdown. (However, the urgency of
this concern has decreased greatly with the adoption of a segmented storage method for pg_clog --- it is
no longer necessary to keep old pg_clog entries around forever.)
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Chapter 12. Write-Ahead Logging (WAL)
With UNDO, it will also be possible to implement savepoints to allow partial rollback of invalid transac-
tion operations (parser errors caused by mistyping commands, insertion of duplicate primary/unique keys
and so on) with the ability to continue or commit valid operations made by the transaction before the error.
At present, any error will invalidate the whole transaction and require a transaction abort.
WAL offers the opportunity for a new method for database on-line backup and restore (BAR). To use this
method, one would have to make periodic saves of data files to another disk, a tape or another host and
also archive the WAL log files. The database file copy and the archived log files could be used to restore
just as if one were restoring after a crash. Each time a new database file copy was made the old log files
could be removed. Implementing this facility will require the logging of data file and index creation and
deletion; it will also require development of a method for copying the data files (operating system copy
commands are not suitable).
A difficulty standing in the way of realizing these benefits is that they require saving WAL entries for con-
siderable periods of time (eg, as long as the longest possible transaction if transaction UNDO is wanted).
The present WAL format is extremely bulky since it includes many disk page snapshots. This is not a
serious concern at present, since the entries only need to be kept for one or two checkpoint intervals; but
to achieve these future benefits some sort of compressed WAL format will be needed.
12.2. Implementation
WAL is automatically enabled from release 7.1 onwards. No action is required from the administrator
with the exception of ensuring that the additional disk-space requirements of the WAL logs are met, and
that any necessary tuning is done (see Section 12.3).
WAL logs are stored in the directory $PGDATA/pg_xlog, as a set of segment files, each 16 MB in size.
Each segment is divided into 8 kB pages. The log record headers are described in access/xlog.h; record
content is dependent on the type of event that is being logged. Segment files are given ever-increasing
numbers as names, starting at 0000000000000000. The numbers do not wrap, at present, but it should
take a very long time to exhaust the available stock of numbers.
The WAL buffers and control structure are in shared memory, and are handled by the backends; they are
protected by lightweight locks. The demand on shared memory is dependent on the number of buffers.
The default size of the WAL buffers is 8 buffers of 8 kB each, or 64 kB total.
It is of advantage if the log is located on another disk than the main database files. This may be achieved
by moving the directory, pg_xlog, to another location (while the postmaster is shut down, of course) and
creating a symbolic link from the original location in $PGDATA to the new location.
The aim of WAL, to ensure that the log is written before database records are altered, may be subverted
by disk drives that falsely report a successful write to the kernel, when, in fact, they have only cached the
data and not yet stored it on the disk. A power failure in such a situation may still lead to irrecoverable
data corruption. Administrators should try to ensure that disks holding PostgreSQL’s log files do not make
such false reports.
12.2.1. Database Recovery with WAL
After a checkpoint has been made and the log flushed, the checkpoint’s position is saved in the file
pg_control. Therefore, when recovery is to be done, the backend first reads pg_control and then
the checkpoint record; then it performs the REDO operation by scanning forward from the log position
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Chapter 12. Write-Ahead Logging (WAL)
indicated in the checkpoint record. Because the entire content of data pages is saved in the log on the
first page modification after a checkpoint, all pages changed since the checkpoint will be restored to a
consistent state.
Using pg_control to get the checkpoint position speeds up the recovery process, but to handle possible
corruption of pg_control, we should actually implement the reading of existing log segments in reverse
order -- newest to oldest -- in order to find the last checkpoint. This has not been implemented, yet.
12.3. WAL Configuration
There are several WAL-related parameters that affect database performance. This section explains their
use. Consult Section 3.4 for details about setting configuration parameters.
Checkpoints are points in the sequence of transactions at which it is guaranteed that the data files have
been updated with all information logged before the checkpoint. At checkpoint time, all dirty data pages
are flushed to disk and a special checkpoint record is written to the log file. As result, in the event of
a crash, the recoverer knows from what record in the log (known as the redo record) it should start the
REDO operation, since any changes made to data files before that record are already on disk. After a
checkpoint has been made, any log segments written before the undo records are no longer needed and
can be recycled or removed. (When WAL-based BAR is implemented, the log segments would be archived
before being recycled or removed.)
The postmaster spawns a special backend process every so often to create the next checkpoint. A check-
point is created every CHECKPOINT_SEGMENTS log segments, or every CHECKPOINT_TIMEOUT seconds,
whichever comes first. The default settings are 3 segments and 300 seconds respectively. It is also possible
to force a checkpoint by using the SQL command CHECKPOINT.
Reducing CHECKPOINT_SEGMENTS and/or CHECKPOINT_TIMEOUT causes checkpoints to be done more
often. This allows faster after-crash recovery (since less work will need to be redone). However, one must
balance this against the increased cost of flushing dirty data pages more often. In addition, to ensure
data page consistency, the first modification of a data page after each checkpoint results in logging the
entire page content. Thus a smaller checkpoint interval increases the volume of output to the log, partially
negating the goal of using a smaller interval, and in any case causing more disk I/O.
There will be at least one 16MB segment file, and will normally not be more than 2 *
CHECKPOINT_SEGMENTS + 1 files. You can use this to estimate space requirements for WAL. Ordinarily,
when old log segment files are no longer needed, they are recycled (renamed to become the next
sequential future segments). If, due to a short-term peak of log output rate, there are more than 2 *
CHECKPOINT_SEGMENTS + 1 segment files, the unneeded segment files will be deleted instead of
recycled until the system gets back under this limit.
There are two commonly used WAL functions: LogInsert and LogFlush. LogInsert is used to place
a new record into the WAL buffers in shared memory. If there is no space for the new record, LogInsert
will have to write (move to kernel cache) a few filled WAL buffers. This is undesirable because LogIn-
sert is used on every database low level modification (for example, tuple insertion) at a time when an
exclusive lock is held on affected data pages, so the operation needs to be as fast as possible. What is
worse, writing WAL buffers may also force the creation of a new log segment, which takes even more
time. Normally, WAL buffers should be written and flushed by a LogFlush request, which is made, for
the most part, at transaction commit time to ensure that transaction records are flushed to permanent stor-
age. On systems with high log output, LogFlush requests may not occur often enough to prevent WAL
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Chapter 12. Write-Ahead Logging (WAL)
buffers being written by LogInsert. On such systems one should increase the number of WAL buffers
by modifying the postgresql.conf WAL_BUFFERS parameter. The default number of WAL buffers is
8. Increasing this value will correspondingly increase shared memory usage.
The COMMIT_DELAY parameter defines for how many microseconds the backend will sleep after writing
a commit record to the log with LogInsert but before performing a LogFlush. This delay allows other
backends to add their commit records to the log so as to have all of them flushed with a single log sync.
No sleep will occur if fsync is not enabled or if fewer than COMMIT_SIBLINGS other backends are not
currently in active transactions; this avoids sleeping when it’s unlikely that any other backend will commit
soon. Note that on most platforms, the resolution of a sleep request is ten milliseconds, so that any nonzero
COMMIT_DELAY setting between 1 and 10000 microseconds will have the same effect. Good values for
these parameters are not yet clear; experimentation is encouraged.
The WAL_SYNC_METHOD parameter determines how PostgreSQL will ask the kernel to force WAL updates
out to disk. All the options should be the same as far as reliability goes, but it’s quite platform-specific
which one will be the fastest. Note that this parameter is irrelevant if FSYNC has been turned off.
Setting the WAL_DEBUG parameter to any nonzero value will result in each LogInsert and LogFlush
WAL call being logged to standard error. At present, it makes no difference what the nonzero value is.
This option may be replaced by a more general mechanism in the future.
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Chapter 13. Regression Tests
13.1. Introduction
The regression tests are a comprehensive set of tests for the SQL implementation in PostgreSQL. They test
standard SQL operations as well as the extended capabilities of PostgreSQL. The test suite was originally
developed by Jolly Chen and Andrew Yu, and was extensively revised and repackaged by Marc Fournier
and Thomas Lockhart. From PostgreSQL 6.1 onward the regression tests are current for every official
release.
13.2. Running the Tests
The regression test can be run against an already installed and running server, or using a temporary in-
stallation within the build tree. Furthermore, there is a “parallel” and a “sequential” mode for running the
tests. The sequential method runs each test script in turn, whereas the parallel method starts up multiple
server processes to run groups of tests in parallel. Parallel testing gives confidence that interprocess com-
munication and locking are working correctly. For historical reasons, the sequential test is usually run
against an existing installation and the parallel method against a temporary installation, but there are no
technical reasons for this.
To run the regression tests after building but before installation, type
$ gmake check
in the top-level directory. (Or you can change to src/test/regress and run the command there.) This
will first build several auxiliary files, such as platform-dependent “expected” files and some sample user-
defined trigger functions, and then run the test driver script. At the end you should see something like
======================
All 77 tests passed.
======================
or otherwise a note about what tests failed. See Section 13.3 below for more.
Note: Because this test method runs a temporary server, it will not work when you are the root user
(the server will not start as root). If you already did the build as root, you do not have to start all over.
Instead, make the regression test directory writable by some other user, log in as that user, and restart
the tests. For example,
root# chmod -R a+w src/test/regress
root# chmod -R a+w contrib/spi
root# su - joeuser
joeuser$ cd top-level build directory
joeuser$ gmake check
(The only possible “security risk” here is that other users might be able to alter the regression test
results behind your back. Use common sense when managing user permissions.)
Alternatively, run the tests after installation.
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Tip: The parallel regression test starts quite a few processes under your user ID. Presently, the maxi-
mum concurrency is twenty parallel test scripts, which means sixty processes --- there’s a backend, a
psql, and usually a shell parent process for the psql for each test script. So if your system enforces a
per-user limit on the number of processes, make sure this limit is at least seventy-five or so, else you
may get random-seeming failures in the parallel test. If you are not in a position to raise the limit, you
can edit the file src/test/regress/parallel_schedule to split the larger concurrent test sets into
more manageable groups.
Tip: On some systems, the default Bourne-compatible shell (/bin/sh) gets confused when it has to
manage too many child processes in parallel. This may cause the parallel test run to lock up or fail. In
such cases, specify a different Bourne-compatible shell on the command line, for example:
$ gmake SHELL=/bin/ksh check
If no non-broken shell is available, you can alter the parallel test schedule as suggested above.
To run the tests after installation (see Chapter 1), initialize a data area and start the server, as explained in
Chapter 3, then type
$ gmake installcheck
The tests will expect to contact the server at the local host and the default port number, unless directed
otherwise by PGHOST and PGPORT environment variables.
13.3. Test Evaluation
Some properly installed and fully functional PostgreSQL installations can “fail” some of these regres-
sion tests due to platform-specific artifacts such as varying floating-point representation and time zone
support. The tests are currently evaluated using a simple diff comparison against the outputs generated
on a reference system, so the results are sensitive to small system differences. When a test is reported as
“failed”, always examine the differences between expected and actual results; you may well find that the
differences are not significant. Nonetheless, we still strive to maintain accurate reference files across all
supported platforms, so it can be expected that all tests pass.
The actual outputs of the regression tests are in files in the src/test/regress/results directory.
The test script uses diff to compare each output file against the reference outputs stored in the
src/test/regress/expected directory. Any differences are saved for your inspection in
src/test/regress/regression.diffs. (Or you can run diff yourself, if you prefer.)
13.3.1. Error message differences
Some of the regression tests involve intentional invalid input values. Error messages can come from either
the PostgreSQL code or from the host platform system routines. In the latter case, the messages may vary
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Chapter 13. Regression Tests
between platforms, but should reflect similar information. These differences in messages will result in a
“failed” regression test that can be validated by inspection.
13.3.2. Locale differences
If you run the tests against an already-installed server that was initialized with a collation order locale
different than C then there may be differences due to sort order and follow-up failures. The regression
test suite is set up to handle this problem by providing alternative result files that together are known to
handle a large number of locales. For example, for the “char” test, the expected file char.out handles
the C and POSIX locales, and the file char_1.out handles many other locales. The regression test driver
will automatically pick the best file to match against when checking for success and for computing failure
differences. (This means that the regression tests cannot detect whether the results are appropriate for the
configured locale. The tests will simply pick the one result file that works best.)
If for some reason the existing expected files do not cover some locale, you can add a new file. The naming
scheme is testname_digit.out. The actual digit is not significant. Remember that the regression test
driver will consider all such files to be equally valid test results. If the test results are platform-dependent,
the technique described in Section 13.4 should be used instead.
13.3.3. Date and time differences
Some of the queries in the horology test will fail if you run the test on the day of a daylight-saving
time changeover, or the day before or after one. These queries assume that the intervals between midnight
yesterday, midnight today and midnight tomorrow are exactly twenty-four hours -- which is wrong if
daylight-saving time went into or out of effect meanwhile.
Most of the date and time results are dependent on the time zone environment. The reference files are
generated for time zone PST8PDT (Berkeley, California) and there will be apparent failures if the tests
are not run with that time zone setting. The regression test driver sets environment variable PGTZ to
PST8PDT, which normally ensures proper results. However, your system must provide library support for
the PST8PDT time zone, or the time zone-dependent tests will fail. To verify that your machine does have
this support, type the following:
$ env TZ=PST8PDT date
The command above should have returned the current system time in the PST8PDT time zone. If the
PST8PDT database is not available, then your system may have returned the time in GMT. If the PST8PDT
time zone is not available, you can set the time zone rules explicitly:
PGTZ=’PST8PDT7,M04.01.0,M10.05.03’; export PGTZ
There appear to be some systems that do not accept the recommended syntax for explicitly setting the
local time zone rules; you may need to use a different PGTZ setting on such machines.
Some systems using older time zone libraries fail to apply daylight-saving corrections to dates before
1970, causing pre-1970 PDT times to be displayed in PST instead. This will result in localized differences
in the test results.
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Chapter 13. Regression Tests
13.3.4. Floating-point differences
Some of the tests involve computing 64-bit (double precision) numbers from table columns. Differ-
ences in results involving mathematical functions of double precision columns have been observed.
The float8 and geometry tests are particularly prone to small differences across platforms, or even with
different compiler optimization options. Human eyeball comparison is needed to determine the real sig-
nificance of these differences which are usually 10 places to the right of the decimal point.
Some systems signal errors from pow() and exp() differently from the mechanism expected by the
current PostgreSQL code.
13.3.5. Polygon differences
Several of the tests involve operations on geographic data about the Oakland/Berkeley, California street
map. The map data is expressed as polygons whose vertices are represented as pairs of double pre-
cision numbers (decimal latitude and longitude). Initially, some tables are created and loaded with ge-
ographic data, then some views are created that join two tables using the polygon intersection operator
(##), then a select is done on the view.
When comparing the results from different platforms, differences occur in the 2nd or 3rd place to the right
of the decimal point. The SQL statements where these problems occur are the following:
SELECT * from street;
SELECT * from iexit;
13.3.6. Row ordering differences
You might see differences in which the same rows are output in a different order than what appears in the
expected file. In most cases this is not, strictly speaking, a bug. Most of the regression test scripts are not
so pedantic as to use an ORDER BY for every single SELECT, and so their result row orderings are not
well-defined according to the letter of the SQL specification. In practice, since we are looking at the same
queries being executed on the same data by the same software, we usually get the same result ordering
on all platforms, and so the lack of ORDER BY isn’t a problem. Some queries do exhibit cross-platform
ordering differences, however. (Ordering differences can also be triggered by non-C locale settings.)
Therefore, if you see an ordering difference, it’s not something to worry about, unless the query does have
an ORDER BY that your result is violating. But please report it anyway, so that we can add an ORDER
BY to that particular query and thereby eliminate the bogus “failure” in future releases.
You might wonder why we don’t order all the regress test queries explicitly to get rid of this issue once
and for all. The reason is that that would make the regression tests less useful, not more, since they’d tend
to exercise query plan types that produce ordered results to the exclusion of those that don’t.
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Chapter 13. Regression Tests
13.3.7. The “random” test
There is at least one case in the “random” test script that is intended to produce random results. This
causes random to fail the regression test once in a while (perhaps once in every five to ten trials). Typing
diff results/random.out expected/random.out
should produce only one or a few lines of differences. You need not worry unless the random test always
fails in repeated attempts. (On the other hand, if the random test is never reported to fail even in many
trials of the regression tests, you probably should worry.)
13.4. Platform-specific comparison files
Since some of the tests inherently produce platform-specific results, we have provided a way to supply
platform-specific result comparison files. Frequently, the same variation applies to multiple platforms;
rather than supplying a separate comparison file for every platform, there is a mapping file that defines
which comparison file to use. So, to eliminate bogus test “failures” for a particular platform, you must
choose or make a variant result file, and then add a line to the mapping file, which is resultmap.
Each line in the mapping file is of the form
testname/platformpattern=comparisonfilename
The test name is just the name of the particular regression test module. The platform pattern is a pattern
in the style of expr (that is, a regular expression with an implicit ^ anchor at the start). It is matched
against the platform name as printed by config.guess followed by :gcc or :cc, depending on whether
you use the GNU compiler or the system’s native compiler (on systems where there is a difference). The
comparison file name is the name of the substitute result comparison file.
For example: some systems using older time zone libraries fail to apply daylight-saving corrections to
dates before 1970, causing pre-1970 PDT times to be displayed in PST instead. This causes a few dif-
ferences in the horology regression test. Therefore, we provide a variant comparison file, horology-
no-DST-before-1970.out, which includes the results to be expected on these systems. To silence the
bogus “failure” message on HPPA platforms, resultmap includes
horology/hppa=horology-no-DST-before-1970
which will trigger on any machine for which the output of config.guess begins with “hppa”. Other
lines in resultmap select the variant comparison file for other platforms where it’s appropriate.
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Appendix A. Release Notes
A.1. Release 7.3.2
Release date: 2003-02-04
This has a variety of fixes from 7.3.1.
A.1.1. Migration to version 7.3.2
A dump/restore is not required for those running 7.3.*.
A.1.2. Changes
Restore creation of OID column in CREATE TABLE AS / SELECT INTO
Fix pg_dump core dump when dumping views having comments
Dump DEFERRABLE/INITIALLY DEFERRED constraints properly
Fix UPDATE when child table’s column numbering differs from parent
Increase default value of max_fsm_relations
Fix problem when fetching backwards in a cursor for a single-row query
Make backward fetch work properly with cursor on SELECT DISTINCT query
Fix problems with loading pg_dump files containing contrib/lo usage
Fix problem with all-numeric user names
Fix possible memory leak and core dump during disconnect in libpgtcl
Make plpython’s spi_execute command handle nulls properly (Andrew Bosma)
Adjust plpython error reporting so that its regression test passes again
Work with bison 1.875
Handle mixed-case names properly in plpgsql’s %type (Neil)
Fix core dump in pltcl when executing a query rewritten by a rule
Repair array subscript overruns (per report from Yichen Xie)
Reduce MAX_TIME_PRECISION from 13 to 10 in floating-point case
Correctly case-fold variable names in per-database and per-user settings
Fix coredump in plpgsql’s RETURN NEXT when SELECT into record returns no rows
Fix outdated use of pg_type.typprtlen in python client interface
Correctly handle fractional seconds in timestamps in JDBC driver
Improve performance of getImportedKeys() in JDBC
Make shared-library symlinks work standardly on HPUX (Giles)
Repair inconsistent rounding behavior for timestamp, time, interval
SSL negotiation fixes (Nathan Mueller)
Make libpq’s ~/.pgpass feature work when connecting with PQconnectDB
Update my2pg, ora2pg
Translation updates
Add casts between types lo and oid in contrib/lo
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Appendix A. Release Notes
fastpath code now checks for privilege to call function
A.2. Release 7.3.1
Release date: 2002-12-18
This has a variety of fixes from 7.3.
A.2.1. Migration to version 7.3.1
A dump/restore is not required for those running 7.3. However, it should be noted that the main Post-
greSQL interface library, libpq, has a new major version number for this release, which will require that
client code using libpq be relinked.
A.2.2. Changes
Fix a core dump of COPY TO when client/server encodings don’t match
(Tom)
Allow pg_dump to work with pre-7.2 servers (Philip)
contrib/adddepend fixes (Tom)
Fix problem with deletion of per-user/per-database config settings
(Tom)
contrib/vacuumlo fix (Tom)
Allow ’password’ encryption even when pg_shadow contains MD5 passwords
(Bruce)
contrib/dbmirror fix (Steven Singer)
Optimizer fixes (Tom)
contrib/tsearch fixes (Teodor Sigaev, Magnus)
Fix encoding name resolution to work in Turkish locale (Nicolai Tufar)
Increment libpq library’s major version number (Bruce)
pg_hba.conf error reporting fixes (Bruce, Neil)
Add SCO OpenServer 5.0.4 as a supported platform (Bruce)
Prevent EXPLAIN from crashing server (Tom)
SSL fixes (Nathan Mueller)
Prevent composite column creation via ALTER TABLE (Tom)
Fix conversion between LATIN9 and UNICODE (Peter)
Translation updates
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Appendix A. Release Notes
A.3. Release 7.3
Release date: 2002-11-27
A.3.1. Overview
Major changes in this release:
Schemas
Schemas allow users to create objects in separate namespaces, so two people or applications can have
tables with the same name. There is also a public schema for shared tables. Table/index creation can
be restricted by removing permissions on the public schema.
Drop Column
PostgreSQL now supports the ALTER TABLE ... DROP COLUMN functionality.
Table Functions
Functions returning multiple rows and/or multiple columns are now much easier to use than before.
You can call such a “table function” in the SELECT FROM clause, treating its output like a table. Also,
PL/pgSQL functions can now return sets.
Prepared Queries
PostgreSQL now supports prepared queries, for improved performance.
Dependency Tracking
PostgreSQL now records object dependencies, which allows improvements in many areas. DROP
statements now take either CASCADE or RESTRICT to control whether dependent objects are also
dropped.
Privileges
Functions and procedural languages now have privileges, and functions can be defined to run with
the privileges of their creator.
Internationalization
Both multibyte and locale support are now always enabled.
Logging
A variety of logging options have been enhanced.
Interfaces
A large number of interfaces have been moved to http://gborg.postgresql.org where they can be de-
veloped and released independently.
Functions/Identifiers
By default, functions can now take up to 32 parameters, and identifiers can be up to 63 bytes long.
Also, OPAQUE is now deprecated: there are specific “pseudo-datatypes” to represent each of the for-
mer meanings of OPAQUE in function argument and result types.
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Appendix A. Release Notes
A.3.2. Migration to version 7.3
A dump/restore using pg_dump is required for those wishing to migrate data from any
previous release. If your application examines the system catalogs, additional changes
will be required due to the introduction of schemas in 7.3; for more information, see:
http://www.ca.postgresql.org/docs/momjian/upgrade_tips_7.3
2
.
Observe the following incompatibilities:
• Pre-6.3 clients are no longer supported.
• pg_hba.conf now has a column for the user name and additional features. Existing files need to be
adjusted.
• Several postgresql.conf logging parameters have been renamed.
• LIMIT #,# has been disabled; use LIMIT # OFFSET #.
• INSERT statements with column lists must specify a value for each specified column. For example,
INSERT INTO tab (col1, col2) VALUES (’val1’) is now invalid. It’s still allowed to supply
fewer columns than expected if the INSERT does not have a column list.
• serial columns are no longer automatically UNIQUE; thus, an index will not automatically be created.
• A SET command inside an aborted transaction is now rolled back.
• COPY no longer considers missing trailing columns to be null. All columns need to be specified. (How-
ever, one may achieve a similar effect by specifying a column list in the COPY command.)
• The data type timestampis now equivalent to timestamp without time zone, instead of times-
tamp with time zone.
• Pre-7.3 databases loaded into 7.3 will not have the new object dependencies for serial columns,
unique constraints, and foreign keys. See the directory contrib/adddepend/ for a detailed descrip-
tion and a script that will add such dependencies.
• An empty string (”) is no longer allowed as the input into an integer field. Formerly, it was silently
interpreted as 0.
A.3.3. Changes
A.3.3.1. Server Operation
Add pg_locks view to show locks (Neil)
Security fixes for password negotiation memory allocation (Neil)
Remove support for version 0 FE/BE protocol (PostgreSQL 6.2 and
2. http://www.ca.postgresql.org/docs/momjian/upgrade_tips_7.3
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Appendix A. Release Notes
earlier) (Tom)
Reserve the last few backend slots for superusers, add parameter
superuser_reserved_connections to control this (Nigel J. Andrews)
A.3.3.2. Performance
Improve startup by calling localtime() only once (Tom)
Cache system catalog information in flat files for faster startup
(Tom)
Improve caching of index information (Tom)
Optimizer improvements (Tom, Fernando Nasser)
Catalog caches now store failed lookups (Tom)
Hash function improvements (Neil)
Improve performance of query tokenization and network handling (Peter)
Speed improvement for large object restore (Mario Weilguni)
Mark expired index entries on first lookup, saving later heap fetches
(Tom)
Avoid excessive NULL bitmap padding (Manfred Koizar)
Add BSD-licensed qsort() for Solaris, for performance (Bruce)
Reduce per-row overhead by four bytes (Manfred Koizar)
Fix GEQO optimizer bug (Neil Conway)
Make WITHOUT OID actually save four bytes per row (Manfred Koizar)
Add default_statistics_target variable to specify ANALYZE buckets
(Neil)
Use local buffer cache for temporary tables so no WAL overhead (Tom)
Improve free space map performance on large tables (Stephen Marshall,
Tom)
Improved WAL write concurrency (Tom)
A.3.3.3. Privileges
Add privileges on functions and procedural languages (Peter)
Add OWNER to CREATE DATABASE so superusers can create databases
on behalf of unprivileged users. (Gavin Sherry, Tom)
Add new object permission bits EXECUTE and USAGE (Tom)
Add SET SESSION AUTHORIZATION DEFAULT and RESET SESSION AUTHORIZATION
(Tom)
Allow functions to be executed with the privilege of the function
owner (Peter)
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Appendix A. Release Notes
A.3.3.4. Server Configuration
Server log messages now tagged with LOG, not DEBUG (Bruce)
Add user column to pg_hba.conf (Bruce)
Have log_connections output two lines in log file (Tom)
Remove debug_level from postgresql.conf, now server_min_messages
(Bruce)
New ALTER DATABASE/USER ... SET command for per-user/database
initialization (Peter)
New parameters server_min_messages and client_min_messages to
control which messages are sent to the server logs or client
applications (Bruce)
Allow pg_hba.conf to specify lists of users/databases separated by
commas, group names prepended with +, and file names prepended
with @ (Bruce)
Remove secondary password file capability and pg_password utility
(Bruce)
Add variable db_user_namespace for database-local user names (Bruce)
SSL improvements (Bear Giles)
Make encryption of stored passwords the default (Bruce)
Allow pg_statistics to be reset by calling pg_stat_reset()
(Christopher)
Add log_duration parameter (Bruce)
Rename debug_print_query to log_statement (Bruce)
Rename show_query_stats to show_statement_stats (Bruce)
Add param log_min_error_statement to print commands to logs on error
(Gavin)
A.3.3.5. Queries
Make cursors insensitive, meaning their contents do not change (Tom)
Disable LIMIT #,# syntax; now only LIMIT # OFFSET # supported (Bruce)
Increase identifier length to 63 (Neil, Bruce)
UNION fixes for merging >= 3 columns of different lengths (Tom)
Add DEFAULT keyword to INSERT, e.g., INSERT ... (..., DEFAULT, ...)
(Rod)
Allow views to have default values using ALTER COLUMN ... SET DEFAULT
(Neil)
Fail on INSERTs with column lists that don’t supply all column
values, e.g., INSERT INTO tab (col1, col2) VALUES (’val1’); (Rod)
Fix for join aliases (Tom)
Fix for FULL OUTER JOINs (Tom)
Improve reporting of invalid identifier and location (Tom, Gavin)
Fix OPEN cursor(args) (Tom)
Allow ’ctid’ to be used in a view and currtid(viewname) (Hiroshi)
Fix for CREATE TABLE AS with UNION (Tom)
SQL99 syntax improvements (Thomas)
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Appendix A. Release Notes
Add statement_timeout variable to cancel queries (Bruce)
Allow prepared queries with PREPARE/EXECUTE (Neil)
Allow FOR UPDATE to appear after LIMIT/OFFSET (Bruce)
Add variable autocommit (Tom, David Van Wie)
A.3.3.6. Object Manipulation
Make equals signs optional in CREATE DATABASE (Gavin Sherry)
Make ALTER TABLE OWNER change index ownership too (Neil)
New ALTER TABLE tabname ALTER COLUMN colname SET STORAGE controls
TOAST storage, compression (John Gray)
Add schema support, CREATE/DROP SCHEMA (Tom)
Create schema for temporary tables (Tom)
Add variable search_path for schema search (Tom)
Add ALTER TABLE SET/DROP NOT NULL (Christopher)
New CREATE FUNCTION volatility levels (Tom)
Make rule names unique only per table (Tom)
Add ’ON tablename’ clause to DROP RULE and COMMENT ON RULE (Tom)
Add ALTER TRIGGER RENAME (Joe)
New current_schema() and current_schemas() inquiry functions (Tom)
Allow functions to return multiple rows (table functions) (Joe)
Make WITH optional in CREATE DATABASE, for consistency (Bruce)
Add object dependency tracking (Rod, Tom)
Add RESTRICT/CASCADE to DROP commands (Rod)
Add ALTER TABLE DROP for non-CHECK CONSTRAINT (Rod)
Autodestroy sequence on DROP of table with SERIAL (Rod)
Prevent column dropping if column is used by foreign key (Rod)
Automatically drop constraints/functions when object is dropped (Rod)
Add CREATE/DROP OPERATOR CLASS (Bill Studenmund, Tom)
Add ALTER TABLE DROP COLUMN (Christopher, Tom, Hiroshi)
Prevent inherited columns from being removed or renamed (Alvaro
Herrera)
Fix foreign key constraints to not error on intermediate database
states (Stephan)
Propagate column or table renaming to foreign key constraints
Add CREATE OR REPLACE VIEW (Gavin, Neil, Tom)
Add CREATE OR REPLACE RULE (Gavin, Neil, Tom)
Have rules execute alphabetically, returning more predictable values
(Tom)
Triggers are now fired in alphabetical order (Tom)
Add /contrib/adddepend to handle pre-7.3 object dependencies (Rod)
Allow better casting when inserting/updating values (Tom)
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Appendix A. Release Notes
A.3.3.7. Utility Commands
Have COPY TO output embedded carriage returns and newlines as \r and
\n (Tom)
Allow DELIMITER in COPY FROM to be 8-bit clean (Tatsuo)
Make pg_dump use ALTER TABLE ADD PRIMARY KEY, for performance (Neil)
Disable brackets in multistatement rules (Bruce)
Disable VACUUM from being called inside a function (Bruce)
Allow dropdb and other scripts to use identifiers with spaces (Bruce)
Restrict database comment changes to the current database
Allow comments on operators, independent of the underlying function
(Rod)
Rollback SET commands in aborted transactions (Tom)
EXPLAIN now outputs as a query (Tom)
Display condition expressions and sort keys in EXPLAIN (Tom)
Add ’SET LOCAL var = value’ to set configuration variables for a
single transaction (Tom)
Allow ANALYZE to run in a transaction (Bruce)
Improve COPY syntax using new WITH clauses, keep backward
compatibility (Bruce)
Fix pg_dump to consistently output tags in non-ASCII dumps (Bruce)
Make foreign key constraints clearer in dump file (Rod)
Add COMMENT ON CONSTRAINT (Rod)
Allow COPY TO/FROM to specify column names (Brent Verner)
Dump UNIQUE and PRIMARY KEY contraints as ALTER TABLE (Rod)
Have SHOW output a query result (Joe)
Generate failure on short COPY lines rather than pad NULLs (Neil)
Fix CLUSTER to preserve all table attributes (Alvaro Herrera)
New pg_settings table to view/modify GUC settings (Joe)
Add smart quoting, portability improvements to pg_dump output (Peter)
Dump serial columns out as SERIAL (Tom)
Enable large file support, >2G for pg_dump (Peter, Philip Warner,
Bruce)
Disallow TRUNCATE on tables that are involved in referential
constraints (Rod)
Have TRUNCATE also auto-truncate the toast table of the relation (Tom)
Add clusterdb utility that will auto-cluster an entire database
based on previous CLUSTER operations (Alvaro Herrera)
Overhaul pg_dumpall (Peter)
Allow REINDEX of TOAST tables (Tom)
Implemented START TRANSACTION, per SQL99 (Neil)
Fix rare index corruption when a page split affects bulk delete (Tom)
Fix ALTER TABLE ... ADD COLUMN for inheritance (Alvaro Herrera)
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Appendix A. Release Notes
A.3.3.8. Data Types and Functions
Fix factorial(0) to return 1 (Bruce)
Date/time/timezone improvements (Thomas)
Fix for array slice extraction (Tom)
Fix extract/date_part to report proper microseconds for timestamp
(Tatsuo)
Allow text_substr() and bytea_substr() to read TOAST values more
efficiently (John Gray)
Add domain support (Rod)
Make WITHOUT TIME ZONE the default for TIMESTAMP and TIME data types
(Thomas)
Allow alternate storage scheme of 64-bit integers for date/time types
using --enable-integer-datetimes in configure (Thomas)
Make timezone(timestamptz) return timestamp rather than a string
(Thomas)
Allow fractional seconds in date/time types for dates prior to 1BC
(Thomas)
Limit timestamp data types to 6 decimal places of precision (Thomas)
Change timezone conversion functions from timetz() to timezone()
(Thomas)
Add configuration variables datestyle and timezone (Tom)
Add OVERLAY(), which allows substitution of a substring in a string
(Thomas)
Add SIMILAR TO (Thomas, Tom)
Add regular expression SUBSTRING(string FROM pat FOR escape) (Thomas)
Add LOCALTIME and LOCALTIMESTAMP functions (Thomas)
Add named composite types using CREATE TYPE typename AS (column)
(Joe)
Allow composite type definition in the table alias clause (Joe)
Add new API to simplify creation of C language table functions (Joe)
Remove ODBC-compatible empty parentheses from calls to SQL99
functions for which these parentheses do not match the standard
(Thomas)
Allow macaddr data type to accept 12 hex digits with no separators
(Mike Wyer)
Add CREATE/DROP CAST (Peter)
Add IS DISTINCT FROM operator (Thomas)
Add SQL99 TREAT() function, synonym for CAST() (Thomas)
Add pg_backend_pid() to output backend pid (Bruce)
Add IS OF / IS NOT OF type predicate (Thomas)
Allow bit string constants without fully-specified length (Thomas)
Allow conversion between 8-byte integers and bit strings (Thomas)
Implement hex literal conversion to bit string literal (Thomas)
Allow table functions to appear in the FROM clause (Joe)
Increase maximum number of function parameters to 32 (Bruce)
No longer automatically create index for SERIAL column (Tom)
Add current_database() (Rod)
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Appendix A. Release Notes
Fix cash_words() to not overflow buffer (Tom)
Add functions replace(), split_part(), to_hex() (Joe)
Fix LIKE for bytea as a right-hand argument (Joe)
Prevent crashes caused by SELECT cash_out(2) (Tom)
Fix to_char(1,’FM999.99’) to return a period (Karel)
Fix trigger/type/language functions returning OPAQUE to return
proper type (Tom)
A.3.3.9. Internationalization
Add additional encodings: Korean (JOHAB), Thai (WIN874), Vietnamese
(TCVN), Arabic (WIN1256), Simplified Chinese (GBK), Korean (UHC)
(Eiji Tokuya)
Enable locale support by default (Peter)
Add locale variables (Peter)
Escape byes >= 0x7f for multibyte in PQescapeBytea/PQunescapeBytea
(Tatsuo)
Add locale awareness to regular expression character classes
Enable multibyte support by default (Tatso)
Add GB18030 multibyte support (Bill Huang)
Add CREATE/DROP CONVERSION, allowing loadable encodings (Tatsuo,
Kaori)
Add pg_conversion table (Tatsuo)
Add SQL99 CONVERT() function (Tatsuo)
pg_dumpall, pg_controldata, and pg_resetxlog now national-language
aware (Peter)
New and updated translations
A.3.3.10. Server-side Languages
Allow recursive SQL function (Peter)
Change PL/Tcl build to use configured compiler and Makefile.shlib
(Peter)
Overhaul the PL/pgSQL FOUND variable to be more Oracle-compatible
(Neil, Tom)
Allow PL/pgSQL to handle quoted identifiers (Tom)
Allow set-returning PL/pgSQL functions (Neil)
Make PL/pgSQL schema-aware (Joe)
Remove some memory leaks (Nigel J. Andrews, Tom)
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Appendix A. Release Notes
A.3.3.11. Psql
Don’t lowercase psql \connect database name for 7.2.0 compatibility
(Tom)
Add psql \timing to time user queries (Greg Sabino Mullane)
Have psql \d show index information (Greg Sabino Mullane)
New psql \dD shows domains (Jonathan Eisler)
Allow psql to show rules on views (Paul ?)
Fix for psql variable substitution (Tom)
Allow psql \d to show temporary table structure (Tom)
Allow psql \d to show foreign keys (Rod)
Fix \? to honor \pset pager (Bruce)
Have psql reports its version number on startup (Tom)
Allow \copy to specify column names (Tom)
A.3.3.12. Libpq
Add $HOME/.pgpass to store host/user password combinations (Alvaro
Herrera)
Add PQunescapeBytea() function to libpq (Patrick Welche)
Fix for sending large queries over non-blocking connections
(Bernhard Herzog)
Fix for libpq using timers on Win9X (David Ford)
Allow libpq notify to handle servers with different-length
identifiers (Tom)
Add libpq PQescapeString() and PQescapeBytea() to Win32 (Bruce)
Fix for SSL with non-blocking connections (Jack Bates)
Add libpq connection timeout parameter (Denis A Ustimenko)
A.3.3.13. JDBC
Allow JDBC to compile with JDK 1.4 (Dave)
Add JDBC 3 support (Barry)
Allows JDBC to set loglevel by adding ?loglevel=X to the connection
URL (Barry)
Add Driver.info() message that prints out the version number (Barry)
Add updateable result sets (Raghu Nidagal, Dave)
Add support for callable statements (Paul Bethe)
Add query cancel capability
Add refresh row (Dave)
Fix MD5 encryption handling for multibyte servers (Jun Kawai)
Add support for prepared statements (Barry)
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Appendix A. Release Notes
A.3.3.14. Miscellaneous Interfaces
Fixed ECPG bug concerning octal numbers in single quotes (Michael)
Move src/interfaces/libpgeasy to http://gborg.postgresql.org (Marc,
Bruce)
Improve Python interface (Elliot Lee, Andrew Johnson, Greg Copeland)
Add libpgtcl connection close event (Gerhard Hintermayer)
Move src/interfaces/libpq++ to http://gborg.postgresql.org (Marc,
Bruce)
Move src/interfaces/odbc to http://gborg.postgresql.org (Marc)
Move src/interfaces/libpgeasy to http://gborg.postgresql.org (Marc,
Bruce)
Move src/interfaces/perl5 to http://gborg.postgresql.org (Marc,
Bruce)
Remove src/bin/pgaccess from main tree, now at
http://www.pgaccess.org (Bruce)
Add pg_on_connection_loss command to libpgtcl (Gerhard Hintermayer,
Tom)
A.3.3.15. Source Code
Fix for parallel make (Peter)
AIX fixes for linking Tcl (Andreas Zeugswetter)
Allow PL/Perl to build under Cygwin (Jason Tishler)
Improve MIPS compiles (Peter, Oliver Elphick)
Require Autoconf version 2.53 (Peter)
Require readline and zlib by default in configure (Peter)
Allow Solaris to use Intimate Shared Memory (ISM), for performance
(Scott Brunza, P.J. Josh Rovero)
Always enable syslog in compile, remove --enable-syslog option
(Tatsuo)
Always enable multibyte in compile, remove --enable-multibyte option
(Tatsuo)
Always enable locale in compile, remove --enable-locale option
(Peter)
Fix for Win9x DLL creation (Magnus Naeslund)
Fix for link() usage by WAL code on Win32, BeOS (Jason Tishler)
Add sys/types.h to c.h, remove from main files (Peter, Bruce)
Fix AIX hang on SMP machines (Tomoyuki Niijima)
AIX SMP hang fix (Tomoyuki Niijima)
Fix pre-1970 date handling on newer glibc libraries (Tom)
Fix PowerPC SMP locking (Tom)
Prevent gcc -ffast-math from being used (Peter, Tom)
Bison >= 1.50 now required for developer builds
Kerberos 5 support now builds with Heimdal (Peter)
Add appendix in the User’s Guide which lists SQL features (Thomas)
Improve loadable module linking to use RTLD_NOW (Tom)
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Appendix A. Release Notes
New error levels WARNING, INFO, LOG, DEBUG[1-5] (Bruce)
New src/port directory holds replaced libc functions (Peter, Bruce)
New pg_namespace system catalog for schemas (Tom)
Add pg_class.relnamespace for schemas (Tom)
Add pg_type.typnamespace for schemas (Tom)
Add pg_proc.pronamespace for schemas (Tom)
Restructure aggregates to have pg_proc entries (Tom)
System relations now have their own namespace, pg_* test not required
(Fernando Nasser)
Rename TOAST index names to be *_index rather than *_idx (Neil)
Add namespaces for operators, opclasses (Tom)
Add additional checks to server control file (Thomas)
New Polish FAQ (Marcin Mazurek)
Add Posix semaphore support (Tom)
Document need for reindex (Bruce)
Rename some internal identifiers to simplify Win32 compile (Jan,
Katherine Ward)
Add documentation on computing disk space (Bruce)
Remove KSQO from GUC (Bruce)
Fix memory leak in rtree (Kenneth Been)
Modify a few error messages for consistency (Bruce)
Remove unused system table columns (Peter)
Make system columns NOT NULL where appropriate (Tom)
Clean up use of sprintf in favor of snprintf() (Neil, Jukka Holappa)
Remove OPAQUE and create specific subtypes (Tom)
Cleanups in array internal handling (Joe, Tom)
Disallow pg_atoi(”) (Bruce)
Remove parameter wal_files because WAL files are now recycled (Bruce)
Add version numbers to heap pages (Tom)
A.3.3.16. Contrib
Allow inet arrays in /contrib/array (Neil)
Gist fixes (Teodor Sigaev, Neil)
Upgrade /contrib/mysql
Add /contrib/dbsize which shows table sizes without vacuum (Peter)
Add /contrib/intagg, integer aggregator routines (mlw)
Improve /contrib/oid2name (Neil, Bruce)
Improve /contrib/tsearch (Oleg, Teodor Sigaev)
Cleanups of /contrib/rserver (Alexey V. Borzov)
Update /contrib/oracle conversion utility (Gilles Darold)
Update /contrib/dblink (Joe)
Improve options supported by /contrib/vacuumlo (Mario Weilguni)
Improvements to /contrib/intarray (Oleg, Teodor Sigaev, Andrey
Oktyabrski)
Add /contrib/reindexdb utility (Shaun Thomas)
Add indexing to /contrib/isbn_issn (Dan Weston)
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Add /contrib/dbmirror (Steven Singer)
Improve /contrib/pgbench (Neil)
Add /contrib/tablefunc table function examples (Joe)
Add /contrib/ltree data type for tree structures (Teodor Sigaev,
Oleg Bartunov)
Move /contrib/pg_controldata, pg_resetxlog into main tree (Bruce)
Fixes to /contrib/cube (Bruno Wolff)
Improve /contrib/fulltextindex (Christopher)
A.4. Release 7.2.4
Release date: 2003-01-30
This has a variety of fixes from 7.2.3, including fixes to prevent possible data loss.
A.4.1. Migration to version 7.2.4
A dump/restore is not required for those running 7.2.X.
A.4.2. Changes
Fix some additional cases of VACUUM "No one parent tuple was found" error
Prevent VACUUM from being called inside a function (Bruce)
Ensure pg_clog updates are sync’d to disk before marking checkpoint complete
Avoid integer overflow during large hash joins
Make GROUP commands work when pg_group.grolist is large enough to be toasted
Fix errors in datetime tables; some timezone names weren’t being recognized
Fix integer overflows in circle_poly(), path_encode(), path_add() (Neil)
Repair long-standing logic errors in lseg_eq(), lseg_ne(), lseg_center()
A.5. Release 7.2.3
Release date: 2002-10-01
This has a variety of fixes from 7.2.2, including fixes to prevent possible data loss.
119
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A.5.1. Migration to version 7.2.3
A dump/restore is not required for those running 7.2.X.
A.5.2. Changes
Prevent possible compressed transaction log loss (Tom)
Prevent non-superuser from increasing most recent vacuum info (Tom)
Handle pre-1970 date values in newer versions of glibc (Tom)
Fix possible hang during server shutdown
Prevent spinlock hangs on SMP PPC machines (Tomoyuki Niijima)
Fix pg_dump to properly dump FULL JOIN USING (Tom)
A.6. Release 7.2.2
Release date: 2002-08-23
This has a variety of fixes from 7.2.1.
A.6.1. Migration to version 7.2.2
A dump/restore is not required for those running 7.2.X.
A.6.2. Changes
Allow EXECUTE of "CREATE TABLE AS ... SELECT" in PL/pgSQL (Tom)
Fix for compressed transaction log id wraparound (Tom)
Fix PQescapeBytea/PQunescapeBytea so that they handle bytes > 0x7f (Tatsuo)
Fix for psql and pg_dump crashing when invoked with non-existand long
options (Tatsuo)
Fix crash when invoking geometric operators (Tom)
Allow OPEN cursor(args) (Tom)
Fix for rtree_gist index build (Teodor)
Fix for dumping user-defined aggregates (Tom)
Contrib/intarray fixes (Oleg)
Fix for complex UNION/EXCEPT/INTERSECT queries using parens (Tom)
Fix to pg_convert (Tatsuo)
Fix for crash with long DATA strings (Thomes, Neil)
Fix for repeat(), lpad(), rpad() and long strings (Neil)
120
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A.7. Release 7.2.1
Release date: 2002-03-21
This has a variety of fixes from 7.2.
A.7.1. Migration to version 7.2.1
A dump/restore is not required for those running 7.2.
A.7.2. Changes
Ensure that sequence counters do not go backwards after a crash (Tom)
Fix pgaccess kanji-coversion key binding (Tatsuo)
Optimizer improvements (Tom)
Cash I/O improvements (Tom)
New Russian FAQ
Compile fix for missing AuthBlockSig (Heiko)
Additional time zones and time zone fixes (Thomas)
Allow psql \connect to handle mixed case database and user names (Tom)
Return proper OID on command completion even with ON INSERT rules (Tom)
Allow COPY FROM to use 8-bit DELIMITERS (Tatsuo)
Fix bug in extract/date_part for milliseconds/microseconds (Tatsuo)
Improve handling of multiple UNIONs with different lengths (Tom)
contrib/btree_gist improvements (Teodor Sigaev)
contrib/tsearch dictionary improvements, see README.tsearch for
an additional installation step (Thomas T. Thai, Teodor Sigaev)
Fix for array subscripts handling (Tom)
Allow EXECUTE of "CREATE TABLE AS ... SELECT" in PL/pgSQL (Tom)
A.8. Release 7.2
Release date: 2002-02-04
121
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A.8.1. Overview
This release improves PostgreSQL for use in high-volume applications.
Major changes in this release:
VACUUM
Vacuuming no longer locks tables, thus allowing normal user access during the vacuum. A new
VACUUM FULL command does old-style vacuum by locking the table and shrinking the on-disk copy
of the table.
Transactions
There is no longer a problem with installations that exceed four billion transactions.
OIDs
OIDs are now optional. Users can now create tables without OIDs for cases where OID usage is
excessive.
Optimizer
The system now computes histogram column statistics during ANALYZE, allowing much better opti-
mizer choices.
Security
A new MD5 encryption option allows more secure storage and transfer of passwords. A new Unix-
domain socket authentication option is available on Linux and BSD systems.
Statistics
Administrators can use the new table access statistics module to get fine-grained information about
table and index usage.
Internationalization
Program and library messages can now be displayed in several languages.
A.8.2. Migration to version 7.2
A dump/restore using pg_dump is required for those wishing to migrate data from any previous release.
Observe the following incompatibilities:
• The semantics of the VACUUM command have changed in this release. You may wish to update your
maintenance procedures accordingly.
• In this release, comparisons using = NULL will always return false (or NULL, more precisely). Previous
releases automatically transformed this syntax to IS NULL. The old behavior can be re-enabled using
a postgresql.conf parameter.
• The pg_hba.conf and pg_ident.conf configuration is now only reloaded after receiving a SIGHUP
signal, not with each connection.
122
Appendix A. Release Notes
• The function octet_length() now returns the uncompressed data length.
• The date/time value ’current’ is no longer available. You will need to rewrite your applications.
• The timestamp(), time(), and interval() functions are no longer available. Instead of times-
tamp(), use timestamp ’string’ or CAST.
The SELECT ... LIMIT #,# syntax will be removed in the next release. You should change your
queries to use separate LIMIT and OFFSET clauses, e.g. LIMIT 10 OFFSET 20.
A.8.3. Changes
A.8.3.1. Server Operation
Create temporary files in a separate directory (Bruce)
Delete orphaned temporary files on postmaster startup (Bruce)
Added unique indexes to some system tables (Tom)
System table operator reorganization (Oleg Bartunov, Teodor Sigaev, Tom)
Renamed pg_log to pg_clog (Tom)
Enable SIGTERM, SIGQUIT to kill backends (Jan)
Removed compile-time limit on number of backends (Tom)
Better cleanup for semaphore resource failure (Tatsuo, Tom)
Allow safe transaction ID wraparound (Tom)
Removed OIDs from some system tables (Tom)
Removed "triggered data change violation" error check (Tom)
SPI portal creation of prepared/saved plans (Jan)
Allow SPI column functions to work for system columns (Tom)
Long value compression improvement (Tom)
Statistics collector for table, index access (Jan)
Truncate extra-long sequence names to a reasonable value (Tom)
Measure transaction times in milliseconds (Thomas)
Fix TID sequential scans (Hiroshi)
Superuser ID now fixed at 1 (Peter E)
New pg_ctl "reload" option (Tom)
A.8.3.2. Performance
Optimizer improvements (Tom)
New histogram column statistics for optimizer (Tom)
Reuse write-ahead log files rather than discarding them (Tom)
Cache improvements (Tom)
IS NULL, IS NOT NULL optimizer improvement (Tom)
Improve lock manager to reduce lock contention (Tom)
Keep relcache entries for index access support functions (Tom)
Allow better selectivity with NaN and infinities in NUMERIC (Tom)
R-tree performance improvements (Kenneth Been)
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Appendix A. Release Notes
B-tree splits more efficient (Tom)
A.8.3.3. Privileges
Change UPDATE, DELETE permissions to be distinct (Peter E)
New REFERENCES, TRIGGER privileges (Peter E)
Allow GRANT/REVOKE to/from more than one user at a time (Peter E)
New has_table_privilege() function (Joe Conway)
Allow non-superuser to vacuum database (Tom)
New SET SESSION AUTHORIZATION command (Peter E)
Fix bug in privilege modifications on newly created tables (Tom)
Disallow access to pg_statistic for non-superuser, add user-accessible views (Tom)
A.8.3.4. Client Authentication
Fork postmaster before doing authentication to prevent hangs (Peter E)
Add ident authentication over Unix domain sockets on Linux, *BSD (Helge Bahmann, Oliver Elphick, Teodor Sigaev, Bruce)
Add a password authentication method that uses MD5 encryption (Bruce)
Allow encryption of stored passwords using MD5 (Bruce)
PAM authentication (Dominic J. Eidson)
Load pg_hba.conf and pg_ident.conf only on startup and SIGHUP (Bruce)
A.8.3.5. Server Configuration
Interpretation of some time zone abbreviations as Australian rather than North American nowsettable at run time (Bruce)
New parameter to set default transaction isolation level (Peter E)
New parameter to enable conversion of "expr = NULL" into "expr IS NULL", off by default (Peter E)
New parameter to control memory usage by VACUUM (Tom)
New parameter to set client authentication timeout (Tom)
New parameter to set maximum number of open files (Tom)
A.8.3.6. Queries
Statements added by INSERT rules now execute after the INSERT (Jan)
Prevent unadorned relation names in target list (Bruce)
NULLs now sort after all normal values in ORDER BY (Tom)
New IS UNKNOWN, IS NOT UNKNOWN Boolean tests (Tom)
New SHARE UPDATE EXCLUSIVE lock mode (Tom)
New EXPLAIN ANALYZE command that shows run times and row counts (Martijn van Oosterhout)
Fix problem with LIMIT and subqueries (Tom)
Fix for LIMIT, DISTINCT ON pushed into subqueries (Tom)
Fix nested EXCEPT/INTERSECT (Tom)
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Appendix A. Release Notes
A.8.3.7. Schema Manipulation
Fix SERIAL in temporary tables (Bruce)
Allow temporary sequences (Bruce)
Sequences now use int8 internally (Tom)
New SERIAL8 creates int8 columns with sequences, default still SERIAL4 (Tom)
Make OIDs optional using WITHOUT OIDS (Tom)
Add %TYPE syntax to CREATE TYPE (Ian Lance Taylor)
Add ALTER TABLE / DROP CONSTRAINT for CHECK constraints (Christopher Kings-Lynne)
NewCREATE OR REPLACE FUNCTION to alter existing function (preserving the function OID) (Gavin Sherry)
Add ALTER TABLE / ADD [ UNIQUE | PRIMARY ] (Christopher Kings-Lynne)
Allow column renaming in views
Make ALTER TABLE / RENAME COLUMN update column names of indexes (Brent Verner)
Fix for ALTER TABLE / ADD CONSTRAINT ... CHECK with inherited tables (Stephan Szabo)
ALTER TABLE RENAME update foreign-key trigger arguments correctly (Brent Verner)
DROP AGGREGATE and COMMENT ON AGGREGATE now accept an aggtype (Tom)
Add automatic return type data casting for SQL functions (Tom)
Allow GiST indexes to handle NULLs and multikey indexes (Oleg Bartunov, Teodor Sigaev, Tom)
Enable partial indexes (Martijn van Oosterhout)
A.8.3.8. Utility Commands
Add RESET ALL, SHOW ALL (Marko Kreen)
CREATE/ALTER USER/GROUP now allow options in any order (Vince)
Add LOCK A, B, C functionality (Neil Padgett)
New ENCRYPTED/UNENCRYPTED option to CREATE/ALTER USER (Bruce)
New light-weight VACUUM does not lock table; old semantics are available as VACUUM FULL (Tom)
Disable COPY TO/FROM on views (Bruce)
COPY DELIMITERS string must be exactly one character (Tom)
VACUUM warning about index tuples fewer than heap now only appears when appropriate (Martijn van Oosterhout)
Fix permission checks for CREATE INDEX (Tom)
Disallow inappropriate use of CREATE/DROP INDEX/TRIGGER/VIEW (Tom)
A.8.3.9. Data Types and Functions
SUM(), AVG(), COUNT() now uses int8 internally for speed (Tom)
Add convert(), convert2() (Tatsuo)
New function bit_length() (Peter E)
Make the "n" in CHAR(n)/VARCHAR(n) represents letters, not bytes (Tatsuo)
CHAR(), VARCHAR() now reject strings that are too long (Peter E)
BIT VARYING now rejects bit strings that are too long (Peter E)
BIT now rejects bit strings that do not match declared size (Peter E)
INET, CIDR text conversion functions (Alex Pilosov)
INET, CIDR operators << and <<= indexable (Alex Pilosov)
Bytea \### now requires valid three digit octal number
Bytea comparison improvements, now supports =, <>, >, >=, <, and <=
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Appendix A. Release Notes
Bytea now supports B-tree indexes
Bytea now supports LIKE, LIKE...ESCAPE, NOT LIKE, NOT LIKE...ESCAPE
Bytea now supports concatenation
New bytea functions: position, substring, trim, btrim, and length
New encode() function mode, "escaped", converts minimally escaped bytea to/from text
Add pg_database_encoding_max_length() (Tatsuo)
Add pg_client_encoding() function (Tatsuo)
now() returns time with millisecond precision (Thomas)
New TIMESTAMP WITHOUT TIMEZONE data type (Thomas)
Add ISO date/time specification with "T", yyyy-mm-ddThh:mm:ss (Thomas)
New xid/int comparison functions (Hiroshi)
Add precision to TIME, TIMESTAMP, and INVERVAL data types (Thomas)
Modify type coercion logic to attempt binary-compatible functions first (Tom)
New encode() function installed by default (Marko Kreen)
Improved to_*() conversion functions (Karel Zak)
Optimize LIKE/ILIKE when using single-byte encodings (Tatsuo)
New functions in contrib/pgcrypto: crypt(), hmac(), encrypt(), gen_salt() (Marko Kreen)
Correct description of translate() function (Bruce)
Add INTERVAL argument for SET TIME ZONE (Thomas)
Add INTERVAL YEAR TO MONTH (etc.) syntax (Thomas)
Optimize length functions when using single-byte encodings (Tatsuo)
Fix path_inter, path_distance, path_length, dist_ppath to handle closed paths (Curtis Barrett, Tom)
octet_length(text) now returns non-compressed length (Tatsuo, Bruce)
Handle "July" full name in date/time literals (Greg Sabino Mullane)
Some datatype() function calls now evaluated differently
Add support for Julian and ISO time specifications (Thomas)
A.8.3.10. Internationalization
National language support in psql, pg_dump, libpq, and server (Peter E)
Message translations in Chinese (simplified, traditional), Czech, French, German, Hungarian, Russian, Swedish (Pe-
ter E, Serguei A. Mokhov, Karel Zak, Weiping He, Zhenbang Wei, Kovacs Zoltan)
Make trim, ltrim, rtrim, btrim, lpad, rpad, translate multibyte aware (Tatsuo)
Add LATIN5,6,7,8,9,10 support (Tatsuo)
Add ISO 8859-5,6,7,8 support (Tatsuo)
Correct LATIN5 to mean ISO-8859-9, not ISO-8859-5 (Tatsuo)
Make mic2ascii() non-ASCII aware (Tatsuo)
Reject invalid multibyte character sequences (Tatsuo)
A.8.3.11. PL/pgSQL
Now uses portals for SELECT loops, allowing huge result sets (Jan)
CURSOR and REFCURSOR support (Jan)
Can now return open cursors (Jan)
Add ELSEIF (Klaus Reger)
Improve PL/pgSQL error reporting, including location of error (Tom)
126
Appendix A. Release Notes
Allow IS or FOR key words in cursor declaration, for compatibility (Bruce)
Fix for SELECT ... FOR UPDATE (Tom)
Fix for PERFORM returning multiple rows (Tom)
Make PL/pgSQL use the server’s type coercion code (Tom)
Memory leak fix (Jan, Tom)
Make trailing semicolon optional (Tom)
A.8.3.12. PL/Perl
New untrusted PL/Perl (Alex Pilosov)
PL/Perl is now built on some platforms even if libperl is not shared (Peter E)
A.8.3.13. PL/Tcl
Now reports errorInfo (Vsevolod Lobko)
Add spi_lastoid function (bob@redivi.com)
A.8.3.14. PL/Python
...is new (Andrew Bosma)
A.8.3.15. Psql
\d displays indexes in unique, primary groupings (Christopher Kings-Lynne)
Allow trailing semicolons in backslash commands (Greg Sabino Mullane)
Read password from /dev/tty if possible
Force new password prompt when changing user and database (Tatsuo, Tom)
Format the correct number of columns for Unicode (Patrice)
A.8.3.16. Libpq
New function PQescapeString() to escape quotes in command strings (Florian Weimer)
New function PQescapeBytea() escapes binary strings for use as SQL string literals
A.8.3.17. JDBC
Return OID of INSERT (Ken K)
Handle more data types (Ken K)
Handle single quotes and newlines in strings (Ken K)
Handle NULL variables (Ken K)
Fix for time zone handling (Barry Lind)
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Improved Druid support
Allow eight-bit characters with non-multibyte server (Barry Lind)
Support BIT, BINARY types (Ned Wolpert)
Reduce memory usage (Michael Stephens, Dave Cramer)
Update DatabaseMetaData (Peter E)
Add DatabaseMetaData.getCatalogs() (Peter E)
Encoding fixes (Anders Bengtsson)
Get/setCatalog methods (Jason Davies)
DatabaseMetaData.getColumns() now returns column defaults (Jason Davies)
DatabaseMetaData.getColumns() performance improvement (Jeroen van Vianen)
Some JDBC1 and JDBC2 merging (Anders Bengtsson)
Transaction performance improvements (Barry Lind)
Array fixes (Greg Zoller)
Serialize addition
Fix batch processing (Rene Pijlman)
ExecSQL method reorganization (Anders Bengtsson)
GetColumn() fixes (Jeroen van Vianen)
Fix isWriteable() function (Rene Pijlman)
Improved passage of JDBC2 conformance tests (Rene Pijlman)
Add bytea type capability (Barry Lind)
Add isNullable() (Rene Pijlman)
JDBC date/time test suite fixes (Liam Stewart)
Fix for SELECT ’id’ AS xxx FROM table (Dave Cramer)
Fix DatabaseMetaData to show precision properly (Mark Lillywhite)
New getImported/getExported keys (Jason Davies)
MD5 password encryption support (Jeremy Wohl)
Fix to actually use type cache (Ned Wolpert)
A.8.3.18. ODBC
Remove query size limit (Hiroshi)
Remove text field size limit (Hiroshi)
Fix for SQLPrimaryKeys in multibyte mode (Hiroshi)
Allow ODBC procedure calls (Hiroshi)
Improve boolean handing (Aidan Mountford)
Most configuration options on setable via DSN (Hiroshi)
Multibyte, performance fixes (Hiroshi)
Allow driver to be used with iODBC or unixODBC (Peter E)
MD5 password encryption support (Bruce)
Add more compatibility functions to odbc.sql (Peter E)
128
Appendix A. Release Notes
A.8.3.19. ECPG
EXECUTE ... INTO implemented (Christof Petig)
Multiple row descriptor support (e.g. CARDINALITY) (Christof Petig)
Fix for GRANT parameters (Lee Kindness)
Fix INITIALLY DEFERRED bug
Various bug fixes (Michael, Christof Petig)
Auto allocation for indicator variable arrays (int *ind_p=NULL)
Auto allocation for string arrays (char **foo_pp=NULL)
ECPGfree_auto_mem fixed
All function names with external linkage are now prefixed by ECPG
Fixes for arrays of structures (Michael)
A.8.3.20. Misc. Interfaces
Python fix fetchone() (Gerhard Haring)
Use UTF, Unicode in Tcl where appropriate (Vsevolod Lobko, Reinhard Max)
Add Tcl COPY TO/FROM (ljb)
Prevent output of default index op class in pg_dump (Tom)
Fix libpgeasy memory leak (Bruce)
A.8.3.21. Build and Install
Configure, dynamic loader, and shared library fixes (Peter E)
Fixes in QNX 4 port (Bernd Tegge)
Fixes in Cygwin and Win32 ports (Jason Tishler, Gerhard Haring, Dmitry Yurtaev, Darko Prenosil, Mikhail Terekhov)
Fix for Win32 socket communication failures (Magnus, Mikhail Terekhov)
Hurd compile fix (Oliver Elphick)
BeOS fixes (Cyril Velter)
Remove configure --enable-unicode-conversion, now enabled by multibyte (Tatsuo)
AIX fixes (Tatsuo, Andreas)
Fix parallel make (Peter E)
Install SQL language manual pages into OS-specific directories (Peter E)
Rename config.h to pg_config.h (Peter E)
Reorganize installation layout of header files (Peter E)
A.8.3.22. Source Code
Remove SEP_CHAR (Bruce)
New GUC hooks (Tom)
Merge GUC and command line handling (Marko Kreen)
Remove EXTEND INDEX (Martijn van Oosterhout, Tom)
New pgjindent utility to indent java code (Bruce)
Remove define of true/false when compiling under C++ (Leandro Fanzone, Tom)
pgindent fixes (Bruce, Tom)
129
Appendix A. Release Notes
Replace strcasecmp() with strcmp() where appropriate (Peter E)
Dynahash portability improvements (Tom)
Add ’volatile’ usage in spinlock structures
Improve signal handling logic (Tom)
A.8.3.23. Contrib
New contrib/rtree_gist (Oleg Bartunov, Teodor Sigaev)
New contrib/tsearch full-text indexing (Oleg, Teodor Sigaev)
Add contrib/dblink for remote database access (Joe Conway)
contrib/ora2pg Oracle conversion utility (Gilles Darold)
contrib/xml XML conversion utility (John Gray)
contrib/fulltextindex fixes (Christopher Kings-Lynne)
New contrib/fuzzystrmatch with levenshtein and metaphone, soundex merged (Joe Conway)
Add contrib/intarray boolean queries, binary search, fixes (Oleg Bartunov)
New pg_upgrade utility (Bruce)
Add new pg_resetxlog options (Bruce, Tom)
A.9. Release 7.1.3
Release date: 2001-08-15
A.9.1. Migration to version 7.1.3
A dump/restore is not required for those running 7.1.X.
A.9.2. Changes
Remove unused WAL segements of large transactions (Tom)
Multiaction rule fix (Tom)
PL/pgSQL memory allocation fix (Jan)
VACUUM buffer fix (Tom)
Regression test fixes (Tom)
pg_dump fixes for GRANT/REVOKE/comments on views, user-defined types (Tom)
Fix subselects with DISTINCT ON or LIMIT (Tom)
BeOS fix
Disable COPY TO/FROM a view (Tom)
Cygwin build (Jason Tishler)
130
Appendix A. Release Notes
A.10. Release 7.1.2
Release date: 2001-05-11
This has one fix from 7.1.1.
A.10.1. Migration to version 7.1.2
A dump/restore is not required for those running 7.1.X.
A.10.2. Changes
Fix PL/pgSQL SELECTs when returning no rows
Fix for psql backslash core dump
Referential integrity permission fix
Optimizer fixes
pg_dump cleanups
A.11. Release 7.1.1
Release date: 2001-05-05
This has a variety of fixes from 7.1.
A.11.1. Migration to version 7.1.1
A dump/restore is not required for those running 7.1.
A.11.2. Changes
Fix for numeric MODULO operator (Tom)
pg_dump fixes (Philip)
pg_dump can dump 7.0 databases (Philip)
readline 4.2 fixes (Peter E)
JOIN fixes (Tom)
AIX, MSWIN, VAX, N32K fixes (Tom)
Multibytes fixes (Tom)
Unicode fixes (Tatsuo)
Optimizer improvements (Tom)
131
Appendix A. Release Notes
Fix for whole tuples in functions (Tom)
Fix for pg_ctl and option strings with spaces (Peter E)
ODBC fixes (Hiroshi)
EXTRACT can now take string argument (Thomas)
Python fixes (Darcy)
A.12. Release 7.1
Release date: 2001-04-13
This release focuses on removing limitations that have existed in the PostgreSQL code for many years.
Major changes in this release:
Write-ahead Log (WAL)
To maintain database consistency in case of an operating system crash, previous releases of Post-
greSQL have forced all data modifications to disk before each transaction commit. With WAL, only
one log file must be flushed to disk, greatly improving performance. If you have been using -F in
previous releases to disable disk flushes, you may want to consider discontinuing its use.
TOAST
TOAST - Previous releases had a compiled-in row length limit, typically 8k - 32k. This limit made
storage of long text fields difficult. With TOAST, long rows of any length can be stored with good
performance.
Outer Joins
We now support outer joins. The UNION/NOT IN workaround for outer joins is no longer required.
We use the SQL92 outer join syntax.
Function Manager
The previous C function manager did not handle null values properly, nor did it support 64-bit CPU’s
(Alpha). The new function manager does. You can continue using your old custom functions, but you
may want to rewrite them in the future to use the new function manager call interface.
Complex Queries
A large number of complex queries that were unsupported in previous releases now work. Many
combinations of views, aggregates, UNION, LIMIT, cursors, subqueries, and inherited tables now
work properly. Inherited tables are now accessed by default. Subqueries in FROM are now supported.
132
Appendix A. Release Notes
A.12.1. Migration to version 7.1
A dump/restore using pg_dump is required for those wishing to migrate data from any previous release.
A.12.2. Changes
Bug Fixes
---------
Many multibyte/Unicode/locale fixes (Tatsuo and others)
More reliable ALTER TABLE RENAME (Tom)
Kerberos V fixes (David Wragg)
Fix for INSERT INTO...SELECT where targetlist has subqueries (Tom)
Prompt username/password on standard error (Bruce)
Large objects inv_read/inv_write fixes (Tom)
Fixes for to_char(), to_date(), to_ascii(), and to_timestamp() (Karel,
Daniel Baldoni)
Prevent query expressions from leaking memory (Tom)
Allow UPDATE of arrays elements (Tom)
Wake up lock waiters during cancel (Hiroshi)
Fix rare cursor crash when using hash join (Tom)
Fix for DROP TABLE/INDEX in rolled-back transaction (Hiroshi)
Fix psql crash from \l+ if MULTIBYTE enabled (Peter E)
Fix truncation of rule names during CREATE VIEW (Ross Reedstrom)
Fix PL/perl (Alex Kapranoff)
Disallow LOCK on views (Mark Hollomon)
Disallow INSERT/UPDATE/DELETE on views (Mark Hollomon)
Disallow DROP RULE, CREATE INDEX, TRUNCATE on views (Mark Hollomon)
Allow PL/pgSQL accept non-ASCII identifiers (Tatsuo)
Allow views to proper handle GROUP BY, aggregates, DISTINCT (Tom)
Fix rare failure with TRUNCATE command (Tom)
Allow UNION/INTERSECT/EXCEPT to be used with ALL, subqueries, views,
DISTINCT, ORDER BY, SELECT...INTO (Tom)
Fix parser failures during aborted transactions (Tom)
Allow temporary relations to properly clean up indexes (Bruce)
Fix VACUUM problem with moving rows in same page (Tom)
Modify pg_dump to better handle user-defined items in template1 (Philip)
Allow LIMIT in VIEW (Tom)
Require cursor FETCH to honor LIMIT (Tom)
Allow PRIMARY/FOREIGN Key definitions on inherited columns (Stephan)
Allow ORDER BY, LIMIT in sub-selects (Tom)
Allow UNION in CREATE RULE (Tom)
Make ALTER/DROP TABLE rollback-able (Vadim, Tom)
Store initdb collation in pg_control so collation cannot be changed (Tom)
Fix INSERT...SELECT with rules (Tom)
Fix FOR UPDATE inside views and subselects (Tom)
Fix OVERLAPS operators conform to SQL92 spec regarding NULLs (Tom)
Fix lpad() and rpad() to handle length less than input string (Tom)
Fix use of NOTIFY in some rules (Tom)
Overhaul btree code (Tom)
Fix NOT NULL use in Pl/pgSQL variables (Tom)
Overhaul GIST code (Oleg)
Fix CLUSTER to preserve constraints and column default (Tom)
133
Appendix A. Release Notes
Improved deadlock detection handling (Tom)
Allow multiple SERIAL columns in a table (Tom)
Prevent occasional index corruption (Vadim)
Enhancements
------------
Add OUTER JOINs (Tom)
Function manager overhaul (Tom)
Allow ALTER TABLE RENAME on indexes (Tom)
Improve CLUSTER (Tom)
Improve ps status display for more platforms (Peter E, Marc)
Improve CREATE FUNCTION failure message (Ross)
JDBC improvements (Peter, Travis Bauer, Christopher Cain, William Webber,
Gunnar)
Grand Unified Configuration scheme/GUC. Many options can now be set in
data/postgresql.conf, postmaster/postgres flags, or SET commands (Peter E)
Improved handling of file descriptor cache (Tom)
New warning code about auto-created table alias entries (Bruce)
Overhaul initdb process (Tom, Peter E)
Overhaul of inherited tables; inherited tables now accessed by default;
new ONLY keyword prevents it (Chris Bitmead, Tom)
ODBC cleanups/improvements (Nick Gorham, Stephan Szabo, Zoltan Kovacs,
Michael Fork)
Allow renaming of temp tables (Tom)
Overhaul memory manager contexts (Tom)
pg_dumpall uses CREATE USER or CREATE GROUP rather using COPY (Peter E)
Overhaul pg_dump (Philip Warner)
Allow pg_hba.conf secondary password file to specify only username (Peter E)
Allow TEMPORARY or TEMP keyword when creating temporary tables (Bruce)
New memory leak checker (Karel)
New SET SESSION CHARACTERISTICS (Thomas)
Allow nested block comments (Thomas)
Add WITHOUT TIME ZONE type qualifier (Thomas)
New ALTER TABLE ADD CONSTRAINT (Stephan)
Use NUMERIC accumulators for INTEGER aggregates (Tom)
Overhaul aggregate code (Tom)
New VARIANCE and STDDEV() aggregates
Improve dependency ordering of pg_dump (Philip)
New pg_restore command (Philip)
New pg_dump tar output option (Philip)
New pg_dump of large objects (Philip)
New ESCAPE option to LIKE (Thomas)
New case-insensitive LIKE - ILIKE (Thomas)
Allow functional indexes to use binary-compatible type (Tom)
Allow SQL functions to be used in more contexts (Tom)
New pg_config utility (Peter E)
New PL/pgSQL EXECUTE command which allows dynamic SQL and utility statements
(Jan)
New PL/pgSQL GET DIAGNOSTICS statement for SPI value access (Jan)
New quote_identifiers() and quote_literal() functions (Jan)
New ALTER TABLE table OWNER TO user command (Mark Hollomon)
Allow subselects in FROM, i.e. FROM (SELECT ...) [AS] alias (Tom)
Update PyGreSQL to version 3.1 (D’Arcy)
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Appendix A. Release Notes
Store tables as files named by OID (Vadim)
New SQL function setval(seq,val,bool) for use in pg_dump (Philip)
Require DROP VIEW to remove views, no DROP TABLE (Mark)
Allow DROP VIEW view1, view2 (Mark)
Allow multiple objects in DROP INDEX, DROP RULE, and DROP TYPE (Tom)
Allow automatic conversion to/from Unicode (Tatsuo, Eiji)
New /contrib/pgcrypto hashing functions (Marko Kreen)
New pg_dumpall --globals-only option (Peter E)
New CHECKPOINT command for WAL which creates new WAL log file (Vadim)
New AT TIME ZONE syntax (Thomas)
Allow location of Unix domain socket to be configurable (David J. MacKenzie)
Allow postmaster to listen on a specific IP address (David J. MacKenzie)
Allow socket path name to be specified in hostname by using leading slash
(David J. MacKenzie)
Allow CREATE DATABASE to specify template database (Tom)
New utility to convert MySQL schema dumps to SQL92 and PostgreSQL (Thomas)
New /contrib/rserv replication toolkit (Vadim)
New file format for COPY BINARY (Tom)
New /contrib/oid2name to map numeric files to table names (B Palmer)
New "idle in transaction" ps status message (Marc)
Update to pgaccess 0.98.7 (Constantin Teodorescu)
pg_ctl now defaults to -w (wait) on shutdown, new -l (log) option
Add rudimentary dependency checking to pg_dump (Philip)
Types
-----
Fix INET/CIDR type ordering and add new functions (Tom)
Make OID behave as an unsigned type (Tom)
Allow BIGINT as synonym for INT8 (Peter E)
New int2 and int8 comparison operators (Tom)
New BIT and BIT VARYING types (Adriaan Joubert, Tom, Peter E)
CHAR() no longer faster than VARCHAR() because of TOAST (Tom)
New GIST seg/cube examples (Gene Selkov)
Improved round(numeric) handling (Tom)
Fix CIDR output formatting (Tom)
New CIDR abbrev() function (Tom)
Performance
-----------
Write-Ahead Log (WAL) to provide crash recovery with less performance
overhead (Vadim)
ANALYZE stage of VACUUM no longer exclusively locks table (Bruce)
Reduced file seeks (Denis Perchine)
Improve BTREE code for duplicate keys (Tom)
Store all large objects in a single table (Denis Perchine, Tom)
Improve memory allocation performance (Karel, Tom)
Source Code
-----------
New function manager call conventions (Tom)
SGI portability fixes (David Kaelbling)
New configure --enable-syslog option (Peter E)
New BSDI README (Bruce)
135
Appendix A. Release Notes
configure script moved to top level, not /src (Peter E)
Makefile/configuration/compilation overhaul (Peter E)
New configure --with-python option (Peter E)
Solaris cleanups (Peter E)
Overhaul /contrib Makefiles (Karel)
New OpenSSL configuration option (Magnus, Peter E)
AIX fixes (Andreas)
QNX fixes (Maurizio)
New heap_open(), heap_openr() API (Tom)
Remove colon and semi-colon operators (Thomas)
New pg_class.relkind value for views (Mark Hollomon)
Rename ichar() to chr() (Karel)
New documentation for btrim(), ascii(), chr(), repeat() (Karel)
Fixes for NT/Cygwin (Pete Forman)
AIX port fixes (Andreas)
New BeOS port (David Reid, Cyril Velter)
Add proofreader’s changes to docs (Addison-Wesley, Bruce)
New Alpha spinlock code (Adriaan Joubert, Compaq)
UnixWare port overhaul (Peter E)
New Darwin/MacOS X port (Peter Bierman, Bruce Hartzler)
New FreeBSD Alpha port (Alfred)
Overhaul shared memory segments (Tom)
Add IBM S/390 support (Neale Ferguson)
Moved macmanuf to /contrib (Larry Rosenman)
Syslog improvements (Larry Rosenman)
New template0 database that contains no user additions (Tom)
New /contrib/cube and /contrib/seg GIST sample code (Gene Selkov)
Allow NetBSD’s libedit instead of readline (Peter)
Improved assembly language source code format (Bruce)
New contrib/pg_logger
New --template option to createdb
New contrib/pg_control utility (Oliver)
New FreeBSD tools ipc_check, start-scripts/freebsd
A.13. Release 7.0.3
Release date: 2000-11-11
This has a variety of fixes from 7.0.2.
A.13.1. Migration to version 7.0.3
A dump/restore is not required for those running 7.0.*.
136
Appendix A. Release Notes
A.13.2. Changes
Jdbc fixes (Peter)
Large object fix (Tom)
Fix lean in COPY WITH OIDS leak (Tom)
Fix backwards-index-scan (Tom)
Fix SELECT ... FOR UPDATE so it checks for duplicate keys (Hiroshi)
Add --enable-syslog to configure (Marc)
Fix abort transaction at backend exit in rare cases (Tom)
Fix for psql \l+ when multibyte enabled (Tatsuo)
Allow PL/pgSQL to accept non ascii identifiers (Tatsuo)
Make vacuum always flush buffers (Tom)
Fix to allow cancel while waiting for a lock (Hiroshi)
Fix for memory aloocation problem in user authentication code (Tom)
Remove bogus use of int4out() (Tom)
Fixes for multiple subqueries in COALESCE or BETWEEN (Tom)
Fix for failure of triggers on heap open in certain cases (Jeroen van
Vianen)
Fix for erroneous selectivity of not-equals (Tom)
Fix for erroneous use of strcmp() (Tom)
Fix for bug where storage manager accesses items beyond end of file
(Tom)
Fix to include kernel errno message in all smgr elog messages (Tom)
Fix for ’.’ not in PATH at build time (SL Baur)
Fix for out-of-file-descriptors error (Tom)
Fix to make pg_dump dump ’iscachable’ flag for functions (Tom)
Fix for subselect in targetlist of Append node (Tom)
Fix for mergejoin plans (Tom)
Fix TRUNCATE failure on relations with indexes (Tom)
Avoid database-wide restart on write error (Hiroshi)
Fix nodeMaterial to honor chgParam by recomputing its output (Tom)
Fix VACUUM problem with moving chain of update tuples when source and
destination of a tuple lie on the same page (Tom)
Fix user.c CommandCounterIncrement (Tom)
Fix for AM/PM boundary problem in to_char() (Karel Zak)
Fix TIME aggregate handling (Tom)
Fix to_char() to avoid coredump on NULL input (Tom)
Buffer fix (Tom)
Fix for inserting/copying longer multibyte strings into char() data
types (Tatsuo)
Fix for crash of backend, on abort (Tom)
A.14. Release 7.0.2
Release date: 2000-06-05
137
Appendix A. Release Notes
This is a repackaging of 7.0.1 with added documentation.
A.14.1. Migration to version 7.0.2
A dump/restore is not required for those running 7.*.
A.14.2. Changes
Added documentation to tarball.
A.15. Release 7.0.1
Release date: 2000-06-01
This is a cleanup release for 7.0.
A.15.1. Migration to version 7.0.1
A dump/restore is not required for those running 7.0.
A.15.2. Changes
Fix many CLUSTER failures (Tom)
Allow ALTER TABLE RENAME works on indexes (Tom)
Fix plpgsql to handle datetime->timestamp and timespan->interval (Bruce)
New configure --with-setproctitle switch to use setproctitle() (Marc, Bruce)
Fix the off by one errors in ResultSet from 6.5.3, and more.
jdbc ResultSet fixes (Joseph Shraibman)
optimizer tunings (Tom)
Fix create user for pgaccess
Fix for UNLISTEN failure
IRIX fixes (David Kaelbling)
QNX fixes (Andreas Kardos)
Reduce COPY IN lock level (Tom)
Change libpqeasy to use PQconnectdb() style parameters (Bruce)
Fix pg_dump to handle OID indexes (Tom)
Fix small memory leak (Tom)
Solaris fix for createdb/dropdb (Tatsuo)
Fix for non-blocking connections (Alfred Perlstein)
Fix improper recovery after RENAME TABLE failures (Tom)
Copy pg_ident.conf.sample into /lib directory in install (Bruce)
138
Appendix A. Release Notes
Add SJIS UDC (NEC selection IBM kanji) support (Eiji Tokuya)
Fix too long syslog message (Tatsuo)
Fix problem with quoted indexes that are too long (Tom)
JDBC ResultSet.getTimestamp() fix (Gregory Krasnow & Floyd Marinescu)
ecpg changes (Michael)
A.16. Release 7.0
Release date: 2000-05-08
This release contains improvements in many areas, demonstrating the continued growth of PostgreSQL.
There are more improvements and fixes in 7.0 than in any previous release. The developers have confi-
dence that this is the best release yet; we do our best to put out only solid releases, and this one is no
exception.
Major changes in this release:
Foreign Keys
Foreign keys are now implemented, with the exception of PARTIAL MATCH foreign keys. Many
users have been asking for this feature, and we are pleased to offer it.
Optimizer Overhaul
Continuing on work started a year ago, the optimizer has been improved, allowing better query plan
selection and faster performance with less memory usage.
Updated psql
psql, our interactive terminal monitor, has been updated with a variety of new features. See the psql
manual page for details.
Join Syntax
SQL92 join syntax is now supported, though only as INNER JOIN for this release. JOIN, NATURAL
JOIN, JOIN/USING, and JOIN/ON are available, as are column correlation names.
A.16.1. Migration to version 7.0
A dump/restore using pg_dump is required for those wishing to migrate data from any previous release of
PostgreSQL. For those upgrading from 6.5.*, you may instead use pg_upgrade to upgrade to this release;
however, a full dump/reload installation is always the most robust method for upgrades.
Interface and compatibility issues to consider for the new release include:
139
Appendix A. Release Notes
• The date/time types datetime and timespan have been superseded by the SQL92-defined types
timestamp and interval. Although there has been some effort to ease the transition by allowing
PostgreSQL to recognize the deprecated type names and translate them to the new type names, this
mechanism may not be completely transparent to your existing application.
• The optimizer has been substantially improved in the area of query cost estimation. In some cases,
this will result in decreased query times as the optimizer makes a better choice for the preferred plan.
However, in a small number of cases, usually involving pathological distributions of data, your query
times may go up. If you are dealing with large amounts of data, you may want to check your queries to
verify performance.
• The JDBC and ODBC interfaces have been upgraded and extended.
• The string function CHAR_LENGTH is now a native function. Previous versions translated this into a
call to LENGTH, which could result in ambiguity with other types implementing LENGTH such as the
geometric types.
A.16.2. Changes
Bug Fixes
---------
Prevent function calls exceeding maximum number of arguments (Tom)
Improve CASE construct (Tom)
Fix SELECT coalesce(f1,0) FROM int4_tbl GROUP BY f1 (Tom)
Fix SELECT sentence.words[0] FROM sentence GROUP BY sentence.words[0] (Tom)
Fix GROUP BY scan bug (Tom)
Improvements in SQL grammar processing (Tom)
Fix for views involved in INSERT ... SELECT ... (Tom)
Fix for SELECT a/2, a/2 FROM test_missing_target GROUP BY a/2 (Tom)
Fix for subselects in INSERT ... SELECT (Tom)
Prevent INSERT ... SELECT ... ORDER BY (Tom)
Fixes for relations greater than 2GB, including vacuum
Improve propagating system table changes to other backends (Tom)
Improve propagating user table changes to other backends (Tom)
Fix handling of temp tables in complex situations (Bruce, Tom)
Allow table locking at table open, improving concurrent reliability (Tom)
Properly quote sequence names in pg_dump (Ross J. Reedstrom)
Prevent DROP DATABASE while others accessing
Prevent any rows from being returned by GROUP BY if no rows processed (Tom)
Fix SELECT COUNT(1) FROM table WHERE ...’ if no rows matching WHERE (Tom)
Fix pg_upgrade so it works for MVCC (Tom)
Fix for SELECT ... WHERE x IN (SELECT ... HAVING SUM(x) > 1) (Tom)
Fix for "f1 datetime DEFAULT ’now’" (Tom)
Fix problems with CURRENT_DATE used in DEFAULT (Tom)
Allow comment-only lines, and ;;; lines too. (Tom)
Improve recovery after failed disk writes, disk full (Hiroshi)
Fix cases where table is mentioned in FROM but not joined (Tom)
Allow HAVING clause without aggregate functions (Tom)
Fix for "--" comment and no trailing newline, as seen in perl interface
Improve pg_dump failure error reports (Bruce)
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Appendix A. Release Notes
Allow sorts and hashes to exceed 2GB file sizes (Tom)
Fix for pg_dump dumping of inherited rules (Tom)
Fix for NULL handling comparisons (Tom)
Fix inconsistent state caused by failed CREATE/DROP commands (Hiroshi)
Fix for dbname with dash
Prevent DROP INDEX from interfering with other backends (Tom)
Fix file descriptor leak in verify_password()
Fix for "Unable to identify an operator =$" problem
Fix ODBC so no segfault if CommLog and Debug enabled (Dirk Niggemann)
Fix for recursive exit call (Massimo)
Fix for extra-long timezones (Jeroen van Vianen)
Make pg_dump preserve primary key information (Peter E)
Prevent databases with single quotes (Peter E)
Prevent DROP DATABASE inside transaction (Peter E)
ecpg memory leak fixes (Stephen Birch)
Fix for SELECT null::text, SELECT int4fac(null) and SELECT 2 + (null) (Tom)
Y2K timestamp fix (Massimo)
Fix for VACUUM ’HEAP_MOVED_IN was not expected’ errors (Tom)
Fix for views with tables/columns containing spaces (Tom)
Prevent permissions on indexes (Peter E)
Fix for spinlock stuck problem when error is generated (Hiroshi)
Fix ipcclean on Linux
Fix handling of NULL constraint conditions (Tom)
Fix memory leak in odbc driver (Nick Gorham)
Fix for permission check on UNION tables (Tom)
Fix to allow SELECT ’a’ LIKE ’a’ (Tom)
Fix for SELECT 1 + NULL (Tom)
Fixes to CHAR
Fix log() on numeric type (Tom)
Deprecate ’:’ and ’;’ operators
Allow vacuum of temporary tables
Disallow inherited columns with the same name as new columns
Recover or force failure when disk space is exhausted (Hiroshi)
Fix INSERT INTO ... SELECT with AS columns matching result columns
Fix INSERT ... SELECT ... GROUP BY groups by target columns not source columns (Tom)
Fix CREATE TABLE test (a char(5) DEFAULT text ”, b int4) with INSERT (Tom)
Fix UNION with LIMIT
Fix CREATE TABLE x AS SELECT 1 UNION SELECT 2
Fix CREATE TABLE test(col char(2) DEFAULT user)
Fix mismatched types in CREATE TABLE ... DEFAULT
Fix SELECT * FROM pg_class where oid in (0,-1)
Fix SELECT COUNT(’asdf’) FROM pg_class WHERE oid=12
Prevent user who can create databases can modifying pg_database table (Pe-
ter E)
Fix btree to give a useful elog when key > 1/2 (page - overhead) (Tom)
Fix INSERT of 0.0 into DECIMAL(4,4) field (Tom)
Enhancements
------------
New CLI interface include file sqlcli.h, based on SQL3/SQL98
Remove all limits on query length, row length limit still exists (Tom)
Update jdbc protocol to 2.0 (Jens Glaser <[email protected]>)
Add TRUNCATE command to quickly truncate relation (Mike Mascari)
141
Appendix A. Release Notes
Fix to give super user and createdb user proper update catalog rights (Pe-
ter E)
Allow ecpg bool variables to have NULL values (Christof)
Issue ecpg error if NULL value for variable with no NULL indicator (Christof)
Allow ^C to cancel COPY command (Massimo)
Add SET FSYNC and SHOW PG_OPTIONS commands(Massimo)
Function name overloading for dynamically-loaded C functions (Frankpitt)
Add CmdTuples() to libpq++(Vince)
New CREATE CONSTRAINT TRIGGER and SET CONSTRAINTS commands(Jan)
Allow CREATE FUNCTION/WITH clause to be used for all language types
configure --enable-debug adds -g (Peter E)
configure --disable-debug removes -g (Peter E)
Allow more complex default expressions (Tom)
First real FOREIGN KEY constraint trigger functionality (Jan)
Add FOREIGN KEY ... MATCH FULL ... ON DELETE CASCADE (Jan)
Add FOREIGN KEY ... MATCH <unspecified> referential actions (Don Baccus)
Allow WHERE restriction on ctid (physical heap location) (Hiroshi)
Move pginterface from contrib to interface directory, rename to pgeasy (Bruce)
Change pgeasy connectdb() parameter ordering (Bruce)
Require SELECT DISTINCT target list to have all ORDER BY columns (Tom)
Add Oracle’s COMMENT ON command (Mike Mascari <[email protected]>)
libpq’s PQsetNoticeProcessor function now returns previous hook(Peter E)
Prevent PQsetNoticeProcessor from being set to NULL (Peter E)
Make USING in COPY optional (Bruce)
Allow subselects in the target list (Tom)
Allow subselects on the left side of comparison operators (Tom)
New parallel regression test (Jan)
Change backend-side COPY to write files with permissions 644 not 666 (Tom)
Force permissions on PGDATA directory to be secure, even if it exists (Tom)
Added psql LASTOID variable to return last inserted oid (Peter E)
Allow concurrent vacuum and remove pg_vlock vacuum lock file (Tom)
Add permissions check for vacuum (Peter E)
New libpq functions to allow asynchronous connections: PQconnectStart(),
PQconnectPoll(), PQresetStart(), PQresetPoll(), PQsetenvStart(),
PQsetenvPoll(), PQsetenvAbort (Ewan Mellor)
New libpq PQsetenv() function (Ewan Mellor)
create/alter user extension (Peter E)
New postmaster.pid and postmaster.opts under $PGDATA (Tatsuo)
New scripts for create/drop user/db (Peter E)
Major psql overhaul (Peter E)
Add const to libpq interface (Peter E)
New libpq function PQoidValue (Peter E)
Show specific non-aggregate causing problem with GROUP BY (Tom)
Make changes to pg_shadow recreate pg_pwd file (Peter E)
Add aggregate(DISTINCT ...) (Tom)
Allow flag to control COPY input/output of NULLs (Peter E)
Make postgres user have a password by default (Peter E)
Add CREATE/ALTER/DROP GROUP (Peter E)
All administration scripts now support --long options (Peter E, Karel)
Vacuumdb script now supports --all option (Peter E)
ecpg new portable FETCH syntax
Add ecpg EXEC SQL IFDEF, EXEC SQL IFNDEF, EXEC SQL ELSE, EXEC SQL ELIF
and EXEC SQL ENDIF directives
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Appendix A. Release Notes
Add pg_ctl script to control backend start-up (Tatsuo)
Add postmaster.opts.default file to store start-up flags (Tatsuo)
Allow --with-mb=SQL_ASCII
Increase maximum number of index keys to 16 (Bruce)
Increase maximum number of function arguments to 16 (Bruce)
Allow configuration of maximum number of index keys and arguments (Bruce)
Allow unprivileged users to change their passwords (Peter E)
Password authentication enabled; required for new users (Peter E)
Disallow dropping a user who owns a database (Peter E)
Change initdb option --with-mb to --enable-multibyte
Add option for initdb to prompts for superuser password (Peter E)
Allow complex type casts like col::numeric(9,2) and col::int2::float8 (Tom)
Updated user interfaces on initdb, initlocation, pg_dump, ipcclean (Peter E)
New pg_char_to_encoding() and pg_encoding_to_char() functions (Tatsuo)
Libpq non-blocking mode (Alfred Perlstein)
Improve conversion of types in casts that don’t specify a length
New plperl internal programming language (Mark Hollomon)
Allow COPY IN to read file that do not end with a newline (Tom)
Indicate when long identifiers are truncated (Tom)
Allow aggregates to use type equivalency (Peter E)
Add Oracle’s to_char(), to_date(), to_datetime(), to_timestamp(), to_number()
Add SELECT DISTINCT ON (expr [, expr ...]) targetlist ... (Tom)
Check to be sure ORDER BY is compatible with the DISTINCT operation (Tom)
Add NUMERIC and int8 types to ODBC
Improve EXPLAIN results for Append, Group, Agg, Unique (Tom)
Add ALTER TABLE ... ADD FOREIGN KEY (Stephan Szabo)
Allow SELECT .. FOR UPDATE in PL/pgSQL (Hiroshi)
Enable backward sequential scan even after reaching EOF (Hiroshi)
Add btree indexing of boolean values, >= and <= (Don Baccus)
Print current line number when COPY FROM fails (Massimo)
Recognize POSIX time zone e.g. "PST+8" and "GMT-8" (Thomas)
Add DEC as synonym for DECIMAL (Thomas)
Add SESSION_USER as SQL92 keyword, same as CURRENT_USER (Thomas)
Implement SQL92 column aliases (aka correlation names) (Thomas)
Implement SQL92 join syntax (Thomas)
Make INTERVAL reserved word allowed as a column identifier (Thomas)
Implement REINDEX command (Hiroshi)
Accept ALL in aggregate function SUM(ALL col) (Tom)
Prevent GROUP BY from using column aliases (Tom)
New psql \encoding option (Tatsuo)
Allow PQrequestCancel() to terminate when in waiting-for-lock state (Hiroshi)
Allow negation of a negative number in all cases
Add ecpg descriptors (Christof, Michael)
Allow CREATE VIEW v AS SELECT f1::char(8) FROM tbl
Allow casts with length, like foo::char(8)
New libpq functions PQsetClientEncoding(), PQclientEncoding() (Tatsuo)
Add support for SJIS user defined characters (Tatsuo)
Larger views/rules supported
Make libpq’s PQconndefaults() thread-safe (Tom)
Disable // as comment to be ANSI conforming, should use -- (Tom)
Allow column aliases on views CREATE VIEW name (collist)
Fixes for views with subqueries (Tom)
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Appendix A. Release Notes
Allow UPDATE table SET fld = (SELECT ...) (Tom)
SET command options no longer require quotes
Update pgaccess to 0.98.6
New SET SEED command
New pg_options.sample file
New SET FSYNC command (Massimo)
Allow pg_descriptions when creating tables
Allow pg_descriptions when creating types, columns, and functions
Allow psql \copy to allow delimiters (Peter E)
Allow psql to print nulls as distinct from "" [null] (Peter E)
Types
-----
Many array fixes (Tom)
Allow bare column names to be subscripted as arrays (Tom)
Improve type casting of int and float constants (Tom)
Cleanups for int8 inputs, range checking, and type conversion (Tom)
Fix for SELECT timespan(’21:11:26’::time) (Tom)
netmask(’x.x.x.x/0’) is 255.255.255.255 instead of 0.0.0.0 (Oleg Sharoiko)
Add btree index on NUMERIC (Jan)
Perl fix for large objects containing NUL characters (Douglas Thomson)
ODBC fix for for large objects (free)
Fix indexing of cidr data type
Fix for Ethernet MAC addresses (macaddr type) comparisons
Fix for date/time types when overflows happened in computations (Tom)
Allow array on int8 (Peter E)
Fix for rounding/overflow of NUMERIC type, like NUMERIC(4,4) (Tom)
Allow NUMERIC arrays
Fix bugs in NUMERIC ceil() and floor() functions (Tom)
Make char_length()/octet_length including trailing blanks (Tom)
Made abstime/reltime use int4 instead of time_t (Peter E)
New lztext data type for compressed text fields
Revise code to handle coercion of int and float constants (Tom)
Start at new code to implement a BIT and BIT VARYING type (Adriaan Joubert)
NUMERIC now accepts scientific notation (Tom)
NUMERIC to int4 rounds (Tom)
Convert float4/8 to NUMERIC properly (Tom)
Allow type conversion with NUMERIC (Thomas)
Make ISO date style (2000-02-16 09:33) the default (Thomas)
Add NATIONAL CHAR [ VARYING ] (Thomas)
Allow NUMERIC round and trunc to accept negative scales (Tom)
New TIME WITH TIME ZONE type (Thomas)
Add MAX()/MIN() on time type (Thomas)
Add abs(), mod(), fac() for int8 (Thomas)
Rename functions to round(), sqrt(), cbrt(), pow() for float8 (Thomas)
Add transcendental math functions (e.g. sin(), acos()) for float8 (Thomas)
Add exp() and ln() for NUMERIC type
Rename NUMERIC power() to pow() (Thomas)
Improved TRANSLATE() function (Edwin Ramirez, Tom)
Allow X=-Y operators (Tom)
Allow SELECT float8(COUNT(*))/(SELECT COUNT(*) FROM t) FROM t GROUP BY f1; (Tom)
Allow LOCALE to use indexes in regular expression searches (Tom)
Allow creation of functional indexes to use default types
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Appendix A. Release Notes
Performance
-----------
Prevent exponential space consumption with many AND’s and OR’s (Tom)
Collect attribute selectivity values for system columns (Tom)
Reduce memory usage of aggregates (Tom)
Fix for LIKE optimization to use indexes with multibyte encodings (Tom)
Fix r-tree index optimizer selectivity (Thomas)
Improve optimizer selectivity computations and functions (Tom)
Optimize btree searching for cases where many equal keys exist (Tom)
Enable fast LIKE index processing only if index present (Tom)
Re-use free space on index pages with duplicates (Tom)
Improve hash join processing (Tom)
Prevent descending sort if result is already sorted(Hiroshi)
Allow commuting of index scan query qualifications (Tom)
Prefer index scans in cases where ORDER BY/GROUP BY is required (Tom)
Allocate large memory requests in fix-sized chunks for performance (Tom)
Fix vacuum’s performance by reducing memory allocation requests (Tom)
Implement constant-expression simplification (Bernard Frankpitt, Tom)
Use secondary columns to be used to determine start of index scan (Hiroshi)
Prevent quadruple use of disk space when doing internal sorting (Tom)
Faster sorting by calling fewer functions (Tom)
Create system indexes to match all system caches (Bruce, Hiroshi)
Make system caches use system indexes (Bruce)
Make all system indexes unique (Bruce)
Improve pg_statistics management for VACUUM speed improvement (Tom)
Flush backend cache less frequently (Tom, Hiroshi)
COPY now reuses previous memory allocation, improving performance (Tom)
Improve optimization cost estimation (Tom)
Improve optimizer estimate of range queries x > lowbound AND x < highbound (Tom)
Use DNF instead of CNF where appropriate (Tom, Taral)
Further cleanup for OR-of-AND WHERE-clauses (Tom)
Make use of index in OR clauses (x = 1 AND y = 2) OR (x = 2 AND y = 4) (Tom)
Smarter optimizer computations for random index page access (Tom)
New SET variable to control optimizer costs (Tom)
Optimizer queries based on LIMIT, OFFSET, and EXISTS qualifications (Tom)
Reduce optimizer internal housekeeping of join paths for speedup (Tom)
Major subquery speedup (Tom)
Fewer fsync writes when fsync is not disabled (Tom)
Improved LIKE optimizer estimates (Tom)
Prevent fsync in SELECT-only queries (Vadim)
Make index creation use psort code, because it is now faster (Tom)
Allow creation of sort temp tables > 1 Gig
Source Tree Changes
-------------------
Fix for linux PPC compile
New generic expression-tree-walker subroutine (Tom)
Change form() to varargform() to prevent portability problems
Improved range checking for large integers on Alphas
Clean up #include in /include directory (Bruce)
Add scripts for checking includes (Bruce)
Remove un-needed #include’s from *.c files (Bruce)
145
Appendix A. Release Notes
Change #include’s to use <> and "" as appropriate (Bruce)
Enable WIN32 compilation of libpq
Alpha spinlock fix from Uncle George <[email protected]>
Overhaul of optimizer data structures (Tom)
Fix to cygipc library (Yutaka Tanida)
Allow pgsql to work on newer Cygwin snapshots (Dan)
New catalog version number (Tom)
Add Linux ARM
Rename heap_replace to heap_update
Update for QNX (Dr. Andreas Kardos)
New platform-specific regression handling (Tom)
Rename oid8 -> oidvector and int28 -> int2vector (Bruce)
Included all yacc and lex files into the distribution (Peter E.)
Remove lextest, no longer needed (Peter E)
Fix for libpq and psql on Win32 (Magnus)
Internally change datetime and timespan into timestamp and interval (Thomas)
Fix for plpgsql on BSD/OS
Add SQL_ASCII test case to the regression test (Tatsuo)
configure --with-mb now deprecated (Tatsuo)
NT fixes
NetBSD fixes (Johnny C. Lam <[email protected]>)
Fixes for Alpha compiles
New multibyte encodings
A.17. Release 6.5.3
Release date: 1999-10-13
This is basically a cleanup release for 6.5.2. We have added a new PgAccess that was missing in 6.5.2,
and installed an NT-specific fix.
A.17.1. Migration to version 6.5.3
A dump/restore is not required for those running 6.5.*.
A.17.2. Changes
Updated version of pgaccess 0.98
NT-specific patch
Fix dumping rules on inherited tables
146
Appendix A. Release Notes
A.18. Release 6.5.2
Release date: 1999-09-15
This is basically a cleanup release for 6.5.1. We have fixed a variety of problems reported by 6.5.1 users.
A.18.1. Migration to version 6.5.2
A dump/restore is not required for those running 6.5.*.
A.18.2. Changes
subselect+CASE fixes(Tom)
Add SHLIB_LINK setting for solaris_i386 and solaris_sparc ports(Daren Sefcik)
Fixes for CASE in WHERE join clauses(Tom)
Fix BTScan abort(Tom)
Repair the check for redundant UNIQUE and PRIMARY KEY indexes(Thomas)
Improve it so that it checks for multicolumn constraints(Thomas)
Fix for Win32 making problem with MB enabled(Hiroki Kataoka)
Allow BSD yacc and bison to compile pl code(Bruce)
Fix SET NAMES working
int8 fixes(Thomas)
Fix vacuum’s memory consumption(Hiroshi,Tatsuo)
Reduce the total memory consumption of vacuum(Tom)
Fix for timestamp(datetime)
Rule deparsing bugfixes(Tom)
Fix quoting problems in mkMakefile.tcldefs.sh.in and mkMakefile.tkdefs.sh.in(Tom)
This is to re-use space on index pages freed by vacuum(Vadim)
document -x for pg_dump(Bruce)
Fix for unary operators in rule deparser(Tom)
Comment out FileUnlink of excess segments during mdtruncate()(Tom)
Repair logic error in LIKE: should not return LIKE_ABORT
when reach end of pattern before end of text(Tom)
Repair incorrect cleanup of heap memory allocation during transaction abort(Tom)
Updated version of pgaccess 0.98
A.19. Release 6.5.1
Release date: 1999-07-15
147
Appendix A. Release Notes
This is basically a cleanup release for 6.5. We have fixed a variety of problems reported by 6.5 users.
A.19.1. Migration to version 6.5.1
A dump/restore is not required for those running 6.5.
A.19.2. Changes
Add NT README file
Portability fixes for linux_ppc, IRIX, linux_alpha, OpenBSD, alpha
Remove QUERY_LIMIT, use SELECT...LIMIT
Fix for EXPLAIN on inheritance(Tom)
Patch to allow vacuum on multisegment tables(Hiroshi)
R-Tree optimizer selectivity fix(Tom)
ACL file descriptor leak fix(Atsushi Ogawa)
New expresssion subtree code(Tom)
Avoid disk writes for read-only transactions(Vadim)
Fix for removal of temp tables if last transaction was aborted(Bruce)
Fix to prevent too large tuple from being created(Bruce)
plpgsql fixes
Allow port numbers 32k - 64k(Bruce)
Add ^ precidence(Bruce)
Rename sort files called pg_temp to pg_sorttemp(Bruce)
Fix for microseconds in time values(Tom)
Tutorial source cleanup
New linux_m68k port
Fix for sorting of NULL’s in some cases(Tom)
Shared library dependencies fixed (Tom)
Fixed glitches affecting GROUP BY in subselects(Tom)
Fix some compiler warnings (Tomoaki Nishiyama)
Add Win1250 (Czech) support (Pavel Behal)
A.20. Release 6.5
Release date: 1999-06-09
This release marks a major step in the development team’s mastery of the source code we inherited from
Berkeley. You will see we are now easily adding major features, thanks to the increasing size and experi-
ence of our world-wide development team.
Here is a brief summary of the more notable changes:
148
Appendix A. Release Notes
Multiversion concurrency control(MVCC)
This removes our old table-level locking, and replaces it with a locking system that is superior to
most commercial database systems. In a traditional system, each row that is modified is locked until
committed, preventing reads by other users. MVCC uses the natural multiversion nature of Post-
greSQL to allow readers to continue reading consistent data during writer activity. Writers continue
to use the compact pg_log transaction system. This is all performed without having to allocate a lock
for every row like traditional database systems. So, basically, we no longer are restricted by simple
table-level locking; we have something better than row-level locking.
Hot backups from pg_dump
pg_dump takes advantage of the new MVCC features to give a consistent database dump/backup
while the database stays online and available for queries.
Numeric data type
We now have a true numeric data type, with user-specified precision.
Temporary tables
Temporary tables are guaranteed to have unique names within a database session, and are destroyed
on session exit.
New SQL features
We now have CASE, INTERSECT, and EXCEPT statement support. We have new LIMIT/OFFSET,
SET TRANSACTION ISOLATION LEVEL, SELECT ... FOR UPDATE, and an improved LOCK
TABLE command.
Speedups
We continue to speed up PostgreSQL, thanks to the variety of talents within our team. We have sped
up memory allocation, optimization, table joins, and row transfer routines.
Ports
We continue to expand our port list, this time including Windows NT/ix86 and NetBSD/arm32.
Interfaces
Most interfaces have new versions, and existing functionality has been improved.
Documentation
New and updated material is present throughout the documentation. New FAQs have been con-
tributed for SGI and AIX platforms. The Tutorial has introductory information on SQL from Stefan
Simkovics. For the User’s Guide, there are reference pages covering the postmaster and more utility
programs, and a new appendix contains details on date/time behavior. The Administrator’s Guide
has a new chapter on troubleshooting from Tom Lane. And the Programmer’s Guide has a descrip-
tion of query processing, also from Stefan, and details on obtaining the PostgreSQL source tree via
anonymous CVS and CVSup.
149
Appendix A. Release Notes
A.20.1. Migration to version 6.5
A dump/restore using pg_dump is required for those wishing to migrate data from any previous release of
PostgreSQL. pg_upgrade can not be used to upgrade to this release because the on-disk structure of the
tables has changed compared to previous releases.
The new Multiversion Concurrency Control (MVCC) features can give somewhat different behaviors in
multiuser environments. Read and understand the following section to ensure that your existing applica-
tions will give you the behavior you need.
A.20.1.1. Multiversion Concurrency Control
Because readers in 6.5 don’t lock data, regardless of transaction isolation level, data read by one transac-
tion can be overwritten by another. In other words, if a row is returned by SELECT it doesn’t mean that
this row really exists at the time it is returned (i.e. sometime after the statement or transaction began)
nor that the row is protected from being deleted or updated by concurrent transactions before the current
transaction does a commit or rollback.
To ensure the actual existence of a row and protect it against concurrent updates one must use SELECT
FOR UPDATE or an appropriate LOCK TABLE statement. This should be taken into account when porting
applications from previous releases of PostgreSQL and other environments.
Keep the above in mind if you are using contrib/refint.* triggers for referential integrity. Additional
techniques are required now. One way is to use LOCK parent_table IN SHARE ROW EXCLUSIVE
MODE command if a transaction is going to update/delete a primary key and use LOCK parent_table
IN SHARE MODE command if a transaction is going to update/insert a foreign key.
Note: Note that if you run a transaction in SERIALIZABLE mode then you must
execute the LOCK commands above before execution of any DML statement
(SELECT/INSERT/DELETE/UPDATE/FETCH/COPY_TO) in the transaction.
These inconveniences will disappear in the future when the ability to read dirty (uncommitted) data (re-
gardless of isolation level) and true referential integrity will be implemented.
A.20.2. Changes
Bug Fixes
---------
Fix text<->float8 and text<->float4 conversion functions(Thomas)
Fix for creating tables with mixed-case constraints(Billy)
Change exp()/pow() behavior to generate error on underflow/overflow(Jan)
Fix bug in pg_dump -z
Memory overrun cleanups(Tatsuo)
Fix for lo_import crash(Tatsuo)
Adjust handling of data type names to suppress double quotes(Thomas)
Use type coercion for matching columns and DEFAULT(Thomas)
Fix deadlock so it only checks once after one second of sleep(Bruce)
150
Appendix A. Release Notes
Fixes for aggregates and PL/pgsql(Hiroshi)
Fix for subquery crash(Vadim)
Fix for libpq function PQfnumber and case-insensitive names(Bahman Rafatjoo)
Fix for large object write-in-middle, no extra block, memory consumption(Tatsuo)
Fix for pg_dump -d or -D and quote special characters in INSERT
Repair serious problems with dynahash(Tom)
Fix INET/CIDR portability problems
Fix problem with selectivity error in ALTER TABLE ADD COLUMN(Bruce)
Fix executor so mergejoin of different column types works(Tom)
Fix for Alpha OR selectivity bug
Fix OR index selectivity problem(Bruce)
Fix so \d shows proper length for char()/varchar()(Ryan)
Fix tutorial code(Clark)
Improve destroyuser checking(Oliver)
Fix for Kerberos(Rodney McDuff)
Fix for dropping database while dirty buffers(Bruce)
Fix so sequence nextval() can be case-sensitive(Bruce)
Fix !!= operator
Drop buffers before destroying database files(Bruce)
Fix case where executor evaluates functions twice(Tatsuo)
Allow sequence nextval actions to be case-sensitive(Bruce)
Fix optimizer indexing not working for negative numbers(Bruce)
Fix for memory leak in executor with fjIsNull
Fix for aggregate memory leaks(Erik Riedel)
Allow username containing a dash GRANT permissions
Cleanup of NULL in inet types
Clean up system table bugs(Tom)
Fix problems of PAGER and \? command(Masaaki Sakaida)
Reduce default multisegment file size limit to 1GB(Peter)
Fix for dumping of CREATE OPERATOR(Tom)
Fix for backward scanning of cursors(Hiroshi Inoue)
Fix for COPY FROM STDIN when using \i(Tom)
Fix for subselect is compared inside an expression(Jan)
Fix handling of error reporting while returning rows(Tom)
Fix problems with reference to array types(Tom,Jan)
Prevent UPDATE SET oid(Jan)
Fix pg_dump so -t option can handle case-sensitive tablenames
Fixes for GROUP BY in special cases(Tom, Jan)
Fix for memory leak in failed queries(Tom)
DEFAULT now supports mixed-case identifiers(Tom)
Fix for multisegment uses of DROP/RENAME table, indexes(Ole Gjerde)
Disable use of pg_dump with both -o and -d options(Bruce)
Allow pg_dump to properly dump GROUP permissions(Bruce)
Fix GROUP BY in INSERT INTO table SELECT * FROM table2(Jan)
Fix for computations in views(Jan)
Fix for aggregates on array indexes(Tom)
Fix for DEFAULT handles single quotes in value requiring too many quotes
Fix security problem with non-super users importing/exporting large objects(Tom)
Rollback of transaction that creates table cleaned up properly(Tom)
Fix to allow long table and column names to generate proper serial names(Tom)
Enhancements
------------
151
Appendix A. Release Notes
Add "vacuumdb" utility
Speed up libpq by allocating memory better(Tom)
EXPLAIN all indexes used(Tom)
Implement CASE, COALESCE, NULLIF expression(Thomas)
New pg_dump table output format(Constantin)
Add string min()/max() functions(Thomas)
Extend new type coercion techniques to aggregates(Thomas)
New moddatetime contrib(Terry)
Update to pgaccess 0.96(Constantin)
Add routines for single-byte "char" type(Thomas)
Improved substr() function(Thomas)
Improved multibyte handling(Tatsuo)
Multiversion concurrency control/MVCC(Vadim)
New Serialized mode(Vadim)
Fix for tables over 2gigs(Peter)
New SET TRANSACTION ISOLATION LEVEL(Vadim)
New LOCK TABLE IN ... MODE(Vadim)
Update ODBC driver(Byron)
New NUMERIC data type(Jan)
New SELECT FOR UPDATE(Vadim)
Handle "NaN" and "Infinity" for input values(Jan)
Improved date/year handling(Thomas)
Improved handling of backend connections(Magnus)
New options ELOG_TIMESTAMPS and USE_SYSLOG options for log files(Massimo)
New TCL_ARRAYS option(Massimo)
New INTERSECT and EXCEPT(Stefan)
New pg_index.indisprimary for primary key tracking(D’Arcy)
New pg_dump option to allow dropping of tables before creation(Brook)
Speedup of row output routines(Tom)
New READ COMMITTED isolation level(Vadim)
New TEMP tables/indexes(Bruce)
Prevent sorting if result is already sorted(Jan)
New memory allocation optimization(Jan)
Allow psql to do \p\g(Bruce)
Allow multiple rule actions(Jan)
Added LIMIT/OFFSET functionality(Jan)
Improve optimizer when joining a large number of tables(Bruce)
New intro to SQL from S. Simkovics’ Master’s Thesis (Stefan, Thomas)
New intro to backend processing from S. Simkovics’ Master’s Thesis (Stefan)
Improved int8 support(Ryan Bradetich, Thomas, Tom)
New routines to convert between int8 and text/varchar types(Thomas)
New bushy plans, where meta-tables are joined(Bruce)
Enable right-hand queries by default(Bruce)
Allow reliable maximum number of backends to be set at configure time
(--with-maxbackends and postmaster switch (-N backends))(Tom)
GEQO default now 10 tables because of optimizer speedups(Tom)
Allow NULL=Var for MS-SQL portability(Michael, Bruce)
Modify contrib check_primary_key() so either "automatic" or "dependent"(Anand)
Allow psql \d on a view show query(Ryan)
Speedup for LIKE(Bruce)
Ecpg fixes/features, see src/interfaces/ecpg/ChangeLog file(Michael)
JDBC fixes/features, see src/interfaces/jdbc/CHANGELOG(Peter)
Make % operator have precedence like /(Bruce)
152
Appendix A. Release Notes
Add new postgres -O option to allow system table structure changes(Bruce)
Update contrib/pginterface/findoidjoins script(Tom)
Major speedup in vacuum of deleted rows with indexes(Vadim)
Allow non-SQL functions to run different versions based on arguments(Tom)
Add -E option that shows actual queries sent by \dt and friends(Masaaki Sakaida)
Add version number in start-up banners for psql(Masaaki Sakaida)
New contrib/vacuumlo removes large objects not referenced(Peter)
New initialization for table sizes so non-vacuumed tables perform better(Tom)
Improve error messages when a connection is rejected(Tom)
Support for arrays of char() and varchar() fields(Massimo)
Overhaul of hash code to increase reliability and performance(Tom)
Update to PyGreSQL 2.4(D’Arcy)
Changed debug options so -d4 and -d5 produce different node displays(Jan)
New pg_options: pretty_plan, pretty_parse, pretty_rewritten(Jan)
Better optimization statistics for system table access(Tom)
Better handling of non-default block sizes(Massimo)
Improve GEQO optimizer memory consumption(Tom)
UNION now suppports ORDER BY of columns not in target list(Jan)
Major libpq++ improvements(Vince Vielhaber)
pg_dump now uses -z(ACL’s) as default(Bruce)
backend cache, memory speedups(Tom)
have pg_dump do everything in one snapshot transaction(Vadim)
fix for large object memory leakage, fix for pg_dumping(Tom)
INET type now respects netmask for comparisons
Make VACUUM ANALYZE only use a readlock(Vadim)
Allow VIEWs on UNIONS(Jan)
pg_dump now can generate consistent snapshots on active databases(Vadim)
Source Tree Changes
-------------------
Improve port matching(Tom)
Portability fixes for SunOS
Add NT/Win32 backend port and enable dynamic loading(Magnus and Daniel Horak)
New port to Cobalt Qube(Mips) running Linux(Tatsuo)
Port to NetBSD/m68k(Mr. Mutsuki Nakajima)
Port to NetBSD/sun3(Mr. Mutsuki Nakajima)
Port to NetBSD/macppc(Toshimi Aoki)
Fix for tcl/tk configuration(Vince)
Removed CURRENT keyword for rule queries(Jan)
NT dynamic loading now works(Daniel Horak)
Add ARM32 support(Andrew McMurry)
Better support for HP-UX 11 and UnixWare
Improve file handling to be more uniform, prevent file descriptor leak(Tom)
New install commands for plpgsql(Jan)
153
Appendix A. Release Notes
A.21. Release 6.4.2
Release date: 1998-12-20
The 6.4.1 release was improperly packaged. This also has one additional bug fix.
A.21.1. Migration to version 6.4.2
A dump/restore is not required for those running 6.4.*.
A.21.2. Changes
Fix for datetime constant problem on some platforms(Thomas)
A.22. Release 6.4.1
Release date: 1998-12-18
This is basically a cleanup release for 6.4. We have fixed a variety of problems reported by 6.4 users.
A.22.1. Migration to version 6.4.1
A dump/restore is not required for those running 6.4.
A.22.2. Changes
Add pg_dump -N flag to force double quotes around identifiers. This is
the default(Thomas)
Fix for NOT in where clause causing crash(Bruce)
EXPLAIN VERBOSE coredump fix(Vadim)
Fix shared-library problems on Linux
Fix test for table existance to allow mixed-case and whitespace in
the table name(Thomas)
Fix a couple of pg_dump bugs
Configure matches template/.similar entries better(Tom)
Change builtin function names from SPI_* to spi_*
OR WHERE clause fix(Vadim)
Fixes for mixed-case table names(Billy)
contrib/linux/postgres.init.csh/sh fix(Thomas)
libpq memory overrun fix
154
Appendix A. Release Notes
SunOS fixes(Tom)
Change exp() behavior to generate error on underflow(Thomas)
pg_dump fixes for memory leak, inheritance constraints, layout change
update pgaccess to 0.93
Fix prototype for 64-bit platforms
Multibyte fixes(Tatsuo)
New ecpg man page
Fix memory overruns(Tatsuo)
Fix for lo_import() crash(Bruce)
Better search for install program(Tom)
Timezone fixes(Tom)
HP-UX fixes(Tom)
Use implicit type coercion for matching DEFAULT values(Thomas)
Add routines to help with single-byte (internal) character type(Thomas)
Compilation of libpq for Win32 fixes(Magnus)
Upgrade to PyGreSQL 2.2(D’Arcy)
A.23. Release 6.4
Release date: 1998-10-30
There are many new features and improvements in this release. Thanks to our developers and maintainers,
nearly every aspect of the system has received some attention since the previous release. Here is a brief,
incomplete summary:
• Views and rules are now functional thanks to extensive new code in the rewrite rules system from Jan
Wieck. He also wrote a chapter on it for the Programmer’s Guide.
• Jan also contributed a second procedural language, PL/pgSQL, to go with the original PL/pgTCL pro-
cedural language he contributed last release.
• We have optional multiple-byte character set support from Tatsuo Ishii to complement our existing
locale support.
• Client/server communications has been cleaned up, with better support for asynchronous messages and
interrupts thanks to Tom Lane.
• The parser will now perform automatic type coercion to match arguments to available operators and
functions, and to match columns and expressions with target columns. This uses a generic mechanism
which supports the type extensibility features of PostgreSQL. There is a new chapter in the User’s
Guide which covers this topic.
• Three new data types have been added. Two types, inet and cidr, support various forms of IP network,
subnet, and machine addressing. There is now an 8-byte integer type available on some platforms. See
the chapter on data types in the User’s Guide for details. A fourth type, serial, is now supported by
the parser as an amalgam of the int4 type, a sequence, and a unique index.
155
Appendix A. Release Notes
• Several more SQL92-compatible syntax features have been added, including INSERT DEFAULT VAL-
UES
• The automatic configuration and installation system has received some attention, and should be more
robust for more platforms than it has ever been.
A.23.1. Migration to version 6.4
A dump/restore using pg_dump or pg_dumpall is required for those wishing to migrate data from any
previous release of PostgreSQL.
A.23.2. Changes
Bug Fixes
---------
Fix for a tiny memory leak in PQsetdb/PQfinish(Bryan)
Remove char2-16 data types, use char/varchar(Darren)
Pqfn not handles a NOTICE message(Anders)
Reduced busywaiting overhead for spinlocks with many backends (dg)
Stuck spinlock detection (dg)
Fix up "ISO-style" timespan decoding and encoding(Thomas)
Fix problem with table drop after rollback of transaction(Vadim)
Change error message and remove non-functional update message(Vadim)
Fix for COPY array checking
Fix for SELECT 1 UNION SELECT NULL
Fix for buffer leaks in large object calls(Pascal)
Change owner from oid to int4 type(Bruce)
Fix a bug in the oracle compatibility functions btrim() ltrim() and rtrim()
Fix for shared invalidation cache overflow(Massimo)
Prevent file descriptor leaks in failed COPY’s(Bruce)
Fix memory leak in libpgtcl’s pg_select(Constantin)
Fix problems with username/passwords over 8 characters(Tom)
Fix problems with handling of asynchronous NOTIFY in backend(Tom)
Fix of many bad system table entries(Tom)
Enhancements
------------
Upgrade ecpg and ecpglib,see src/interfaces/ecpc/ChangeLog(Michael)
Show the index used in an EXPLAIN(Zeugswetter)
EXPLAIN invokes rule system and shows plan(s) for rewritten queries(Jan)
Multibyte awareness of many data types and functions, via configure(Tatsuo)
New configure --with-mb option(Tatsuo)
New initdb --pgencoding option(Tatsuo)
New createdb -E multibyte option(Tatsuo)
Select version(); now returns PostgreSQL version(Jeroen)
Libpq now allows asynchronous clients(Tom)
Allow cancel from client of backend query(Tom)
Psql now cancels query with Control-C(Tom)
Libpq users need not issue dummy queries to get NOTIFY messages(Tom)
156
Appendix A. Release Notes
NOTIFY now sends sender’s PID, so you can tell whether it was your own(Tom)
PGresult struct now includes associated error message, if any(Tom)
Define "tz_hour" and "tz_minute" arguments to date_part()(Thomas)
Add routines to convert between varchar and bpchar(Thomas)
Add routines to allow sizing of varchar and bpchar into target columns(Thomas)
Add bit flags to support timezonehour and minute in data retrieval(Thomas)
Allow more variations on valid floating point numbers (e.g. ".1", "1e6")(Thomas)
Fixes for unary minus parsing with leading spaces(Thomas)
Implement TIMEZONE_HOUR, TIMEZONE_MINUTE per SQL92 specs(Thomas)
Check for and properly ignore FOREIGN KEY column constraints(Thomas)
Define USER as synonym for CURRENT_USER per SQL92 specs(Thomas)
Enable HAVING clause but no fixes elsewhere yet.
Make "char" type a synonym for "char(1)" (actually implemented as bpchar)(Thomas)
Save string type if specified for DEFAULT clause handling(Thomas)
Coerce operations involving different data types(Thomas)
Allow some index use for columns of different types(Thomas)
Add capabilities for automatic type conversion(Thomas)
Cleanups for large objects, so file is truncated on open(Peter)
Readline cleanups(Tom)
Allow psql \f \ to make spaces as delimiter(Bruce)
Pass pg_attribute.atttypmod to the frontend for column field lengths(Tom,Bruce)
Msql compatibility library in /contrib(Aldrin)
Remove the requirement that ORDER/GROUP BY clause identifiers be
included in the target list(David)
Convert columns to match columns in UNION clauses(Thomas)
Remove fork()/exec() and only do fork()(Bruce)
Jdbc cleanups(Peter)
Show backend status on ps command line(only works on some platforms)(Bruce)
Pg_hba.conf now has a sameuser option in the database field
Make lo_unlink take oid param, not int4
New DISABLE_COMPLEX_MACRO for compilers that can’t handle our macros(Bruce)
Libpgtcl now handles NOTIFY as a Tcl event, need not send dummy queries(Tom)
libpgtcl cleanups(Tom)
Add -error option to libpgtcl’s pg_result command(Tom)
New locale patch, see docs/README/locale(Oleg)
Fix for pg_dump so CONSTRAINT and CHECK syntax is correct(ccb)
New contrib/lo code for large object orphan removal(Peter)
New psql command "SET CLIENT_ENCODING TO ’encoding’" for multibytes
feature, see /doc/README.mb(Tatsuo)
/contrib/noupdate code to revoke update permission on a column
Libpq can now be compiled on win32(Magnus)
Add PQsetdbLogin() in libpq
New 8-byte integer type, checked by configure for OS support(Thomas)
Better support for quoted table/column names(Thomas)
Surround table and column names with double-quotes in pg_dump(Thomas)
PQreset() now works with passwords(Tom)
Handle case of GROUP BY target list column number out of range(David)
Allow UNION in subselects
Add auto-size to screen to \d? commands(Bruce)
Use UNION to show all \d? results in one query(Bruce)
Add \d? field search feature(Bruce)
Pg_dump issues fewer \connect requests(Tom)
Make pg_dump -z flag work better, document it in manual page(Tom)
157
Appendix A. Release Notes
Add HAVING clause with full support for subselects and unions(Stephan)
Full text indexing routines in contrib/fulltextindex(Maarten)
Transaction ids now stored in shared memory(Vadim)
New PGCLIENTENCODING when issuing COPY command(Tatsuo)
Support for SQL92 syntax "SET NAMES"(Tatsuo)
Support for LATIN2-5(Tatsuo)
Add UNICODE regression test case(Tatsuo)
Lock manager cleanup, new locking modes for LLL(Vadim)
Allow index use with OR clauses(Bruce)
Allows "SELECT NULL ORDER BY 1;"
Explain VERBOSE prints the plan, and now pretty-prints the plan to
the postmaster log file(Bruce)
Add indexes display to \d command(Bruce)
Allow GROUP BY on functions(David)
New pg_class.relkind for large objects(Bruce)
New way to send libpq NOTICE messages to a different location(Tom)
New \w write command to psql(Bruce)
New /contrib/findoidjoins scans oid columns to find join relationships(Bruce)
Allow binary-compatible indexes to be considered when checking for valid
Indexes for restriction clauses containing a constant(Thomas)
New ISBN/ISSN code in /contrib/isbn_issn
Allow NOT LIKE, IN, NOT IN, BETWEEN, and NOT BETWEEN constraint(Thomas)
New rewrite system fixes many problems with rules and views(Jan)
* Rules on relations work
* Event qualifications on insert/update/delete work
* New OLD variable to reference CURRENT, CURRENT will be remove in future
* Update rules can reference NEW and OLD in rule qualifications/actions
* Insert/update/delete rules on views work
* Multiple rule actions are now supported, surrounded by parentheses
* Regular users can create views/rules on tables they have RULE permits
* Rules and views inherit the permissions on the creator
* No rules at the column level
* No UPDATE NEW/OLD rules
* New pg_tables, pg_indexes, pg_rules and pg_views system views
* Only a single action on SELECT rules
* Total rewrite overhaul, perhaps for 6.5
* handle subselects
* handle aggregates on views
* handle insert into select from view works
System indexes are now multikey(Bruce)
Oidint2, oidint4, and oidname types are removed(Bruce)
Use system cache for more system table lookups(Bruce)
New backend programming language PL/pgSQL in backend/pl(Jan)
New SERIAL data type, auto-creates sequence/index(Thomas)
Enable assert checking without a recompile(Massimo)
User lock enhancements(Massimo)
New setval() command to set sequence value(Massimo)
Auto-remove unix socket file on start-up if no postmaster running(Massimo)
Conditional trace package(Massimo)
New UNLISTEN command(Massimo)
Psql and libpq now compile under win32 using win32.mak(Magnus)
Lo_read no longer stores trailing NULL(Bruce)
Identifiers are now truncated to 31 characters internally(Bruce)
158
Appendix A. Release Notes
Createuser options now availble on the command line
Code for 64-bit integer supported added, configure tested, int8 type(Thomas)
Prevent file descriptor leaf from failed COPY(Bruce)
New pg_upgrade command(Bruce)
Updated /contrib directories(Massimo)
New CREATE TABLE DEFAULT VALUES statement available(Thomas)
New INSERT INTO TABLE DEFAULT VALUES statement available(Thomas)
New DECLARE and FETCH feature(Thomas)
libpq’s internal structures now not exported(Tom)
Allow up to 8 key indexes(Bruce)
Remove ARCHIVE keyword, that is no longer used(Thomas)
pg_dump -n flag to supress quotes around indentifiers
disable system columns for views(Jan)
new INET and CIDR types for network addresses(TomH, Paul)
no more double quotes in psql output
pg_dump now dumps views(Terry)
new SET QUERY_LIMIT(Tatsuo,Jan)
Source Tree Changes
-------------------
/contrib cleanup(Jun)
Inline some small functions called for every row(Bruce)
Alpha/linux fixes
HP-UX cleanups(Tom)
Multibyte regression tests(Soonmyung.)
Remove --disabled options from configure
Define PGDOC to use POSTGRESDIR by default
Make regression optional
Remove extra braces code to pgindent(Bruce)
Add bsdi shared library support(Bruce)
New --without-CXX support configure option(Brook)
New FAQ_CVS
Update backend flowchart in tools/backend(Bruce)
Change atttypmod from int16 to int32(Bruce, Tom)
Getrusage() fix for platforms that do not have it(Tom)
Add PQconnectdb, PGUSER, PGPASSWORD to libpq man page
NS32K platform fixes(Phil Nelson, John Buller)
SCO 7/UnixWare 2.x fixes(Billy,others)
Sparc/Solaris 2.5 fixes(Ryan)
Pgbuiltin.3 is obsolete, move to doc files(Thomas)
Even more documention(Thomas)
Nextstep support(Jacek)
Aix support(David)
pginterface manual page(Bruce)
shared libraries all have version numbers
merged all OS-specific shared library defines into one file
smarter TCL/TK configuration checking(Billy)
smarter perl configuration(Brook)
configure uses supplied install-sh if no install script found(Tom)
new Makefile.shlib for shared library configuration(Tom)
159
Appendix A. Release Notes
A.24. Release 6.3.2
Release date: 1998-04-07
This is a bug-fix release for 6.3.x. Refer to the release notes for version 6.3 for a more complete summary
of new features.
Summary:
• Repairs automatic configuration support for some platforms, including Linux, from breakage inadver-
tently introduced in version 6.3.1.
• Correctly handles function calls on the left side of BETWEEN and LIKE clauses.
A dump/restore is NOT required for those running 6.3 or 6.3.1. A make distclean, make, and make
install is all that is required. This last step should be performed while the postmaster is not running.
You should re-link any custom applications that use PostgreSQL libraries.
For upgrades from pre-6.3 installations, refer to the installation and migration instructions for version 6.3.
A.24.1. Changes
Configure detection improvements for tcl/tk(Brook Milligan, Alvin)
Manual page improvements(Bruce)
BETWEEN and LIKE fix(Thomas)
fix for psql \connect used by pg_dump(Oliver Elphick)
New odbc driver
pgaccess, version 0.86
qsort removed, now uses libc version, cleanups(Jeroen)
fix for buffer over-runs detected(Maurice Gittens)
fix for buffer overrun in libpgtcl(Randy Kunkee)
fix for UNION with DISTINCT or ORDER BY(Bruce)
gettimeofday configure check(Doug Winterburn)
Fix "indexes not used" bug(Vadim)
docs additions(Thomas)
Fix for backend memory leak(Bruce)
libreadline cleanup(Erwan MAS)
Remove DISTDIR(Bruce)
Makefile dependency cleanup(Jeroen van Vianen)
ASSERT fixes(Bruce)
160
Appendix A. Release Notes
A.25. Release 6.3.1
Release date: 1998-03-23
Summary:
• Additional support for multibyte character sets.
• Repair byte ordering for mixed-endian clients and servers.
• Minor updates to allowed SQL syntax.
• Improvements to the configuration autodetection for installation.
A dump/restore is NOT required for those running 6.3. A make distclean, make, and make install
is all that is required. This last step should be performed while the postmaster is not running. You should
re-link any custom applications that use PostgreSQL libraries.
For upgrades from pre-6.3 installations, refer to the installation and migration instructions for version 6.3.
A.25.1. Changes
ecpg cleanup/fixes, now version 1.1(Michael Meskes)
pg_user cleanup(Bruce)
large object fix for pg_dump and tclsh (alvin)
LIKE fix for multiple adjacent underscores
fix for redefining builtin functions(Thomas)
ultrix4 cleanup
upgrade to pg_access 0.83
updated CLUSTER manual page
multibyte character set support, see doc/README.mb(Tatsuo)
configure --with-pgport fix
pg_ident fix
big-endian fix for backend communications(Kataoka)
SUBSTR() and substring() fix(Jan)
several jdbc fixes(Peter)
libpgtcl improvements, see libptcl/README(Randy Kunkee)
Fix for "Datasize = 0" error(Vadim)
Prevent \do from wrapping(Bruce)
Remove duplicate Russian character set entries
Sunos4 cleanup
Allow optional TABLE keyword in LOCK and SELECT INTO(Thomas)
CREATE SEQUENCE options to allow a negative integer(Thomas)
Add "PASSWORD" as an allowed column identifier(Thomas)
Add checks for UNION target fields(Bruce)
Fix Alpha port(Dwayne Bailey)
Fix for text arrays containing quotes(Doug Gibson)
Solaris compile fix(Albert Chin-A-Young)
Better identify tcl and tk libs and includes(Bruce)
161
Appendix A. Release Notes
A.26. Release 6.3
Release date: 1998-03-01
There are many new features and improvements in this release. Here is a brief, incomplete summary:
• Many new SQL features, including full SQL92 subselect capability (everything is here but target-list
subselects).
• Support for client-side environment variables to specify time zone and date style.
• Socket interface for client/server connection. This is the default now so you may need to start postmaster
with the -i flag.
• Better password authorization mechanisms. Default table permissions have changed.
• Old-style time travel has been removed. Performance has been improved.
Note: Bruce Momjian wrote the following notes to introduce the new release.
There are some general 6.3 issues that I want to mention. These are only the big items that can not be
described in one sentence. A review of the detailed changes list is still needed.
First, we now have subselects. Now that we have them, I would like to mention that without subselects,
SQL is a very limited language. Subselects are a major feature, and you should review your code for
places where subselects provide a better solution for your queries. I think you will find that there are more
uses for subselects than you may think. Vadim has put us on the big SQL map with subselects, and fully
functional ones too. The only thing you can’t do with subselects is to use them in the target list.
Second, 6.3 uses Unix domain sockets rather than TCP/IP by default. To enable connections from other
machines, you have to use the new postmaster -i option, and of course edit pg_hba.conf. Also, for this
reason, the format of pg_hba.conf has changed.
Third, char() fields will now allow faster access than varchar() or text. Specifically, the text and
varchar() have a penalty for access to any columns after the first column of this type. char() used
to also have this access penalty, but it no longer does. This may suggest that you redesign some of your
tables, especially if you have short character columns that you have defined as varchar() or text. This
and other changes make 6.3 even faster than earlier releases.
We now have passwords definable independent of any Unix file. There are new SQL USER commands.
See the Administrator’s Guide for more information. There is a new table, pg_shadow, which is used to
store user information and user passwords, and it by default only SELECT-able by the postgres super-user.
162
Appendix A. Release Notes
pg_user is now a view of pg_shadow, and is SELECT-able by PUBLIC. You should keep using pg_user
in your application without changes.
User-created tables now no longer have SELECT permission to PUBLIC by default. This was done be-
cause the ANSI standard requires it. You can of course GRANT any permissions you want after the table
is created. System tables continue to be SELECT-able by PUBLIC.
We also have real deadlock detection code. No more sixty-second timeouts. And the new locking code
implements a FIFO better, so there should be less resource starvation during heavy use.
Many complaints have been made about inadequate documentation in previous releases. Thomas has put
much effort into many new manuals for this release. Check out the doc/ directory.
For performance reasons, time travel is gone, but can be implemented using triggers (see
pgsql/contrib/spi/README). Please check out the new \d command for types, operators, etc. Also,
views have their own permissions now, not based on the underlying tables, so permissions on them have
to be set separately. Check /pgsql/interfaces for some new ways to talk to PostgreSQL.
This is the first release that really required an explanation for existing users. In many ways, this was
necessary because the new release removes many limitations, and the work-arounds people were using
are no longer needed.
A.26.1. Migration to version 6.3
A dump/restore using pg_dump or pg_dumpall is required for those wishing to migrate data from any
previous release of PostgreSQL.
A.26.2. Changes
Bug Fixes
---------
Fix binary cursors broken by MOVE implementation(Vadim)
Fix for tcl library crash(Jan)
Fix for array handling, from Gerhard Hintermayer
Fix acl error, and remove duplicate pqtrace(Bruce)
Fix psql \e for empty file(Bruce)
Fix for textcat on varchar() fields(Bruce)
Fix for DBT Sendproc (Zeugswetter Andres)
Fix vacuum analyze syntax problem(Bruce)
Fix for international identifiers(Tatsuo)
Fix aggregates on inherited tables(Bruce)
Fix substr() for out-of-bounds data
Fix for select 1=1 or 2=2, select 1=1 and 2=2, and select sum(2+2)(Bruce)
Fix notty output to show status result. -q option still turns it off(Bruce)
Fix for count(*), aggs with views and multiple tables and sum(3)(Bruce)
Fix cluster(Bruce)
Fix for PQtrace start/stop several times(Bruce)
Fix a variety of locking problems like newer lock waiters getting
lock before older waiters, and having readlock people not share
locks if a writer is waiting for a lock, and waiting writers not
getting priority over waiting readers(Bruce)
Fix crashes in psql when executing queries from external files(James)
163
Appendix A. Release Notes
Fix problem with multiple order by columns, with the first one having
NULL values(Jeroen)
Use correct hash table support functions for float8 and int4(Thomas)
Re-enable JOIN= option in CREATE OPERATOR statement (Thomas)
Change precedence for boolean operators to match expected behavior(Thomas)
Generate elog(ERROR) on over-large integer(Bruce)
Allow multiple-argument functions in constraint clauses(Thomas)
Check boolean input literals for ’true’,’false’,’yes’,’no’,’1’,’0’
and throw elog(ERROR) if unrecognized(Thomas)
Major large objects fix
Fix for GROUP BY showing duplicates(Vadim)
Fix for index scans in MergeJion(Vadim)
Enhancements
------------
Subselects with EXISTS, IN, ALL, ANY keywords (Vadim, Bruce, Thomas)
New User Manual(Thomas, others)
Speedup by inlining some frequently-called functions
Real deadlock detection, no more timeouts(Bruce)
Add SQL92 "constants" CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP,
CURRENT_USER(Thomas)
Modify constraint syntax to be SQL92-compliant(Thomas)
Implement SQL92 PRIMARY KEY and UNIQUE clauses using indexes(Thomas)
Recognize SQL92 syntax for FOREIGN KEY. Throw elog notice(Thomas)
Allow NOT NULL UNIQUE constraint clause (each allowed separately before)(Thomas)
Allow PostgreSQL-style casting ("::") of non-constants(Thomas)
Add support for SQL3 TRUE and FALSE boolean constants(Thomas)
Support SQL92 syntax for IS TRUE/IS FALSE/IS NOT TRUE/IS NOT FALSE(Thomas)
Allow shorter strings for boolean literals (e.g. "t", "tr", "tru")(Thomas)
Allow SQL92 delimited identifiers(Thomas)
Implement SQL92 binary and hexadecimal string decoding (b’10’ and x’1F’)(Thomas)
Support SQL92 syntax for type coercion of literal strings
(e.g. "DATETIME ’now’")(Thomas)
Add conversions for int2, int4, and OID types to and from text(Thomas)
Use shared lock when building indexes(Vadim)
Free memory allocated for an user query inside transaction block after
this query is done, was turned off in <= 6.2.1(Vadim)
New SQL statement CREATE PROCEDURAL LANGUAGE(Jan)
New PostgreSQL Procedural Language (PL) backend interface(Jan)
Rename pg_dump -H option to -h(Bruce)
Add Java support for passwords, European dates(Peter)
Use indexes for LIKE and ~, !~ operations(Bruce)
Add hash functions for datetime and timespan(Thomas)
Time Travel removed(Vadim, Bruce)
Add paging for \d and \z, and fix \i(Bruce)
Add Unix domain socket support to backend and to frontend library(Goran)
Implement CREATE DATABASE/WITH LOCATION and initlocation utility(Thomas)
Allow more SQL92 and/or PostgreSQL reserved words as column identifiers(Thomas)
Augment support for SQL92 SET TIME ZONE...(Thomas)
SET/SHOW/RESET TIME ZONE uses TZ backend environment variable(Thomas)
Implement SET keyword = DEFAULT and SET TIME ZONE DEFAULT(Thomas)
Enable SET TIME ZONE using TZ environment variable(Thomas)
Add PGDATESTYLE environment variable to frontend and backend initialization(Thomas)
164
Appendix A. Release Notes
Add PGTZ, PGCOSTHEAP, PGCOSTINDEX, PGRPLANS, PGGEQO
frontend library initialization environment variables(Thomas)
Regression tests time zone automatically set with "setenv PGTZ PST8PDT"(Thomas)
Add pg_description table for info on tables, columns, operators, types, and
aggregates(Bruce)
Increase 16 char limit on system table/index names to 32 characters(Bruce)
Rename system indexes(Bruce)
Add ’GERMAN’ option to SET DATESTYLE(Thomas)
Define an "ISO-style" timespan output format with "hh:mm:ss" fields(Thomas)
Allow fractional values for delta times (e.g. ’2.5 days’)(Thomas)
Validate numeric input more carefully for delta times(Thomas)
Implement day of year as possible input to date_part()(Thomas)
Define timespan_finite() and text_timespan() functions(Thomas)
Remove archive stuff(Bruce)
Allow for a pg_password authentication database that is separate from
the system password file(Todd)
Dump ACLs, GRANT, REVOKE permissions(Matt)
Define text, varchar, and bpchar string length functions(Thomas)
Fix Query handling for inheritance, and cost computations(Bruce)
Implement CREATE TABLE/AS SELECT (alternative to SELECT/INTO)(Thomas)
Allow NOT, IS NULL, IS NOT NULL in constraints(Thomas)
Implement UNIONs for SELECT(Bruce)
Add UNION, GROUP, DISTINCT to INSERT(Bruce)
varchar() stores only necessary bytes on disk(Bruce)
Fix for BLOBs(Peter)
Mega-Patch for JDBC...see README_6.3 for list of changes(Peter)
Remove unused "option" from PQconnectdb()
New LOCK command and lock manual page describing deadlocks(Bruce)
Add new psql \da, \dd, \df, \do, \dS, and \dT commands(Bruce)
Enhance psql \z to show sequences(Bruce)
Show NOT NULL and DEFAULT in psql \d table(Bruce)
New psql .psqlrc file start-up(Andrew)
Modify sample start-up script in contrib/linux to show syslog(Thomas)
New types for IP and MAC addresses in contrib/ip_and_mac(TomH)
Unix system time conversions with date/time types in contrib/unixdate(Thomas)
Update of contrib stuff(Massimo)
Add Unix socket support to DBD::Pg(Goran)
New python interface (PyGreSQL 2.0)(D’Arcy)
New frontend/backend protocol has a version number, network byte order(Phil)
Security features in pg_hba.conf enhanced and documented, many cleanups(Phil)
CHAR() now faster access than VARCHAR() or TEXT
ecpg embedded SQL preprocessor
Reduce system column overhead(Vadmin)
Remove pg_time table(Vadim)
Add pg_type attribute to identify types that need length (bpchar, varchar)
Add report of offending line when COPY command fails
Allow VIEW permissions to be set separately from the underlying tables.
For security, use GRANT/REVOKE on views as appropriate(Jan)
Tables now have no default GRANT SELECT TO PUBLIC. You must
explicitly grant such permissions.
Clean up tutorial examples(Darren)
Source Tree Changes
165
Appendix A. Release Notes
-------------------
Add new html development tools, and flow chart in /tools/backend
Fix for SCO compiles
Stratus computer port Robert Gillies
Added support for shlib for BSD44_derived & i386_solaris
Make configure more automated(Brook)
Add script to check regression test results
Break parser functions into smaller files, group together(Bruce)
Rename heap_create to heap_create_and_catalog, rename heap_creatr
to heap_create()(Bruce)
Sparc/Linux patch for locking(TomS)
Remove PORTNAME and reorganize port-specific stuff(Marc)
Add optimizer README file(Bruce)
Remove some recursion in optimizer and clean up some code there(Bruce)
Fix for NetBSD locking(Henry)
Fix for libptcl make(Tatsuo)
AIX patch(Darren)
Change IS TRUE, IS FALSE, ... to expressions using "=" rather than
function calls to istrue() or isfalse() to allow optimization(Thomas)
Various fixes NetBSD/Sparc related(TomH)
Alpha linux locking(Travis,Ryan)
Change elog(WARN) to elog(ERROR)(Bruce)
FAQ for FreeBSD(Marc)
Bring in the PostODBC source tree as part of our standard distribution(Marc)
A minor patch for HP/UX 10 vs 9(Stan)
New pg_attribute.atttypmod for type-specific info like varchar length(Bruce)
UnixWare patches(Billy)
New i386 ’lock’ for spin lock asm(Billy)
Support for multiplexed backends is removed
Start an OpenBSD port
Start an AUX port
Start a Cygnus port
Add string functions to regression suite(Thomas)
Expand a few function names formerly truncated to 16 characters(Thomas)
Remove un-needed malloc() calls and replace with palloc()(Bruce)
A.27. Release 6.2.1
Release date: 1997-10-17
6.2.1 is a bug-fix and usability release on 6.2.
Summary:
• Allow strings to span lines, per SQL92.
• Include example trigger function for inserting user names on table updates.
166
Appendix A. Release Notes
This is a minor bug-fix release on 6.2. For upgrades from pre-6.2 systems, a full dump/reload is required.
Refer to the 6.2 release notes for instructions.
A.27.1. Migration from version 6.2 to version 6.2.1
This is a minor bug-fix release. A dump/reload is not required from version 6.2, but is required from any
release prior to 6.2.
In upgrading from version 6.2, if you choose to dump/reload you will find that avg(money) is now calcu-
lated correctly. All other bug fixes take effect upon updating the executables.
Another way to avoid dump/reload is to use the following SQL command from psql to update the existing
system table:
update pg_aggregate set aggfinalfn = ’cash_div_flt8’
where aggname = ’avg’ and aggbasetype = 790;
This will need to be done to every existing database, including template1.
A.27.2. Changes
Allow TIME and TYPE column names(Thomas)
Allow larger range of true/false as boolean values(Thomas)
Support output of "now" and "current"(Thomas)
Handle DEFAULT with INSERT of NULL properly(Vadim)
Fix for relation reference counts problem in buffer manager(Vadim)
Allow strings to span lines, like ANSI(Thomas)
Fix for backward cursor with ORDER BY(Vadim)
Fix avg(cash) computation(Thomas)
Fix for specifying a column twice in ORDER/GROUP BY(Vadim)
Documented new libpq function to return affected rows, PQcmdTuples(Bruce)
Trigger function for inserting user names for INSERT/UPDATE(Brook Milligan)
A.28. Release 6.2
Release date: 1997-10-02
A dump/restore is required for those wishing to migrate data from previous releases of PostgreSQL.
167
Appendix A. Release Notes
A.28.1. Migration from version 6.1 to version 6.2
This migration requires a complete dump of the 6.1 database and a restore of the database in 6.2.
Note that the pg_dump and pg_dumpall utility from 6.2 should be used to dump the 6.1 database.
A.28.2. Migration from version 1.x to version 6.2
Those migrating from earlier 1.* releases should first upgrade to 1.09 because the COPY output format
was improved from the 1.02 release.
A.28.3. Changes
Bug Fixes
---------
Fix problems with pg_dump for inheritance, sequences, archive tables(Bruce)
Fix compile errors on overflow due to shifts, unsigned, and bad prototypes
from Solaris(Diab Jerius)
Fix bugs in geometric line arithmetic (bad intersection calculations)(Thomas)
Check for geometric intersections at endpoints to avoid rounding ugliness(Thomas)
Catch non-functional delete attempts(Vadim)
Change time function names to be more consistent(Michael Reifenberg)
Check for zero divides(Michael Reifenberg)
Fix very old bug which made tuples changed/inserted by a commnd
visible to the command itself (so we had multiple update of
updated tuples, etc)(Vadim)
Fix for SELECT null, ’fail’ FROM pg_am (Patrick)
SELECT NULL as EMPTY_FIELD now allowed(Patrick)
Remove un-needed signal stuff from contrib/pginterface
Fix OR (where x != 1 or x isnull didn’t return tuples with x NULL) (Vadim)
Fix time_cmp function (Vadim)
Fix handling of functions with non-attribute first argument in
WHERE clauses (Vadim)
Fix GROUP BY when order of entries is different from order
in target list (Vadim)
Fix pg_dump for aggregates without sfunc1 (Vadim)
Enhancements
------------
Default genetic optimizer GEQO parameter is now 8(Bruce)
Allow use parameters in target list having aggregates in functions(Vadim)
Added JDBC driver as an interface(Adrian & Peter)
pg_password utility
Return number of tuples inserted/affected by INSERT/UPDATE/DELETE etc.(Vadim)
Triggers implemented with CREATE TRIGGER (SQL3)(Vadim)
SPI (Server Programming Interface) allows execution of queries inside
C-functions (Vadim)
NOT NULL implemented (SQL92)(Robson Paniago de Miranda)
Include reserved words for string handling, outer joins, and unions(Thomas)
Implement extended comments ("/* ... */") using exclusive states(Thomas)
Add "//" single-line comments(Bruce)
168
Appendix A. Release Notes
Remove some restrictions on characters in operator names(Thomas)
DEFAULT and CONSTRAINT for tables implemented (SQL92)(Vadim & Thomas)
Add text concatenation operator and function (SQL92)(Thomas)
Support WITH TIME ZONE syntax (SQL92)(Thomas)
Support INTERVAL unit TO unit syntax (SQL92)(Thomas)
Define types DOUBLE PRECISION, INTERVAL, CHARACTER,
and CHARACTER VARYING (SQL92)(Thomas)
Define type FLOAT(p) and rudimentary DECIMAL(p,s), NUMERIC(p,s) (SQL92)(Thomas)
Define EXTRACT(), POSITION(), SUBSTRING(), and TRIM() (SQL92)(Thomas)
Define CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP (SQL92)(Thomas)
Add syntax and warnings for UNION, HAVING, INNER and OUTER JOIN (SQL92)(Thomas)
Add more reserved words, mostly for SQL92 compliance(Thomas)
Allow hh:mm:ss time entry for timespan/reltime types(Thomas)
Add center() routines for lseg, path, polygon(Thomas)
Add distance() routines for circle-polygon, polygon-polygon(Thomas)
Check explicitly for points and polygons contained within polygons
using an axis-crossing algorithm(Thomas)
Add routine to convert circle-box(Thomas)
Merge conflicting operators for different geometric data types(Thomas)
Replace distance operator "<===>" with "<->"(Thomas)
Replace "above" operator "!^" with ">^" and "below" operator "!|" with "<^"(Thomas)
Add routines for text trimming on both ends, substring, and string position(Thomas)
Added conversion routines circle(box) and poly(circle)(Thomas)
Allow internal sorts to be stored in memory rather than in files(Bruce & Vadim)
Allow functions and operators on internally-identical types to succeed(Bruce)
Speed up backend start-up after profiling analysis(Bruce)
Inline frequently called functions for performance(Bruce)
Reduce open() calls(Bruce)
psql: Add PAGER for \h and \?,\C fix
Fix for psql pager when no tty(Bruce)
New entab utility(Bruce)
General trigger functions for referential integrity (Vadim)
General trigger functions for time travel (Vadim)
General trigger functions for AUTOINCREMENT/IDENTITY feature (Vadim)
MOVE implementation (Vadim)
Source Tree Changes
-------------------
HP-UX 10 patches (Vladimir Turin)
Added SCO support, (Daniel Harris)
MkLinux patches (Tatsuo Ishii)
Change geometric box terminology from "length" to "width"(Thomas)
Deprecate temporary unstored slope fields in geometric code(Thomas)
Remove restart instructions from INSTALL(Bruce)
Look in /usr/ucb first for install(Bruce)
Fix c++ copy example code(Thomas)
Add -o to psql manual page(Bruce)
Prevent relname unallocated string length from being copied into database(Bruce)
Cleanup for NAMEDATALEN use(Bruce)
Fix pg_proc names over 15 chars in output(Bruce)
Add strNcpy() function(Bruce)
remove some (void) casts that are unnecessary(Bruce)
new interfaces directory(Marc)
169
Appendix A. Release Notes
Replace fopen() calls with calls to fd.c functions(Bruce)
Make functions static where possible(Bruce)
enclose unused functions in #ifdef NOT_USED(Bruce)
Remove call to difftime() in timestamp support to fix SunOS(Bruce & Thomas)
Changes for Digital Unix
Portability fix for pg_dumpall(Bruce)
Rename pg_attribute.attnvals to attdispersion(Bruce)
"intro/unix" manual page now "pgintro"(Bruce)
"built-in" manual page now "pgbuiltin"(Bruce)
"drop" manual page now "drop_table"(Bruce)
Add "create_trigger", "drop_trigger" manual pages(Thomas)
Add constraints regression test(Vadim & Thomas)
Add comments syntax regression test(Thomas)
Add PGINDENT and support program(Bruce)
Massive commit to run PGINDENT on all *.c and *.h files(Bruce)
Files moved to /src/tools directory(Bruce)
SPI and Trigger programming guides (Vadim & D’Arcy)
A.29. Release 6.1.1
Release date: 1997-07-22
A.29.1. Migration from version 6.1 to version 6.1.1
This is a minor bug-fix release. A dump/reload is not required from version 6.1, but is required from any
release prior to 6.1. Refer to the release notes for 6.1 for more details.
A.29.2. Changes
fix for SET with options (Thomas)
allow pg_dump/pg_dumpall to preserve ownership of all tables/objects(Bruce)
new psql \connect option allows changing usernames without changing databases
fix for initdb --debug option(Yoshihiko Ichikawa))
lextest cleanup(Bruce)
hash fixes(Vadim)
fix date/time month boundary arithmetic(Thomas)
fix timezone daylight handling for some ports(Thomas, Bruce, Tatsuo)
timestamp overhauled to use standard functions(Thomas)
other code cleanup in date/time routines(Thomas)
psql’s \d now case-insensitive(Bruce)
psql’s backslash commands can now have trailing semicolon(Bruce)
fix memory leak in psql when using \g(Bruce)
major fix for endian handling of communication to server(Thomas, Tatsuo)
Fix for Solaris assembler and include files(Yoshihiko Ichikawa)
170
Appendix A. Release Notes
allow underscores in usernames(Bruce)
pg_dumpall now returns proper status, portability fix(Bruce)
A.30. Release 6.1
Release date: 1997-06-08
The regression tests have been adapted and extensively modified for the 6.1 release of PostgreSQL.
Three new data types (datetime, timespan, and circle) have been added to the native set of Post-
greSQL types. Points, boxes, paths, and polygons have had their output formats made consistent across
the data types. The polygon output in misc.out has only been spot-checked for correctness relative to the
original regression output.
PostgreSQL 6.1 introduces a new, alternate optimizer which uses genetic algorithms. These algorithms
introduce a random behavior in the ordering of query results when the query contains multiple qualifiers
or multiple tables (giving the optimizer a choice on order of evaluation). Several regression tests have been
modified to explicitly order the results, and hence are insensitive to optimizer choices. A few regression
tests are for data types which are inherently unordered (e.g. points and time intervals) and tests involving
those types are explicitly bracketed with set geqo to ’off’ and reset geqo.
The interpretation of array specifiers (the curly braces around atomic values) appears to have changed
sometime after the original regression tests were generated. The current ./expected/*.out files reflect
this new interpretation, which may not be correct!
The float8 regression test fails on at least some platforms. This is due to differences in implementations
of pow() and exp() and the signaling mechanisms used for overflow and underflow conditions.
The “random” results in the random test should cause the “random” test to be “failed”, since the regression
tests are evaluated using a simple diff. However, “random” does not seem to produce random results on
my test machine (Linux/gcc/i686).
A.30.1. Migration to version 6.1
This migration requires a complete dump of the 6.0 database and a restore of the database in 6.1.
Those migrating from earlier 1.* releases should first upgrade to 1.09 because the COPY output format
was improved from the 1.02 release.
A.30.2. Changes
Bug Fixes
---------
packet length checking in library routines
171
Appendix A. Release Notes
lock manager priority patch
check for under/over flow of float8(Bruce)
multitable join fix(Vadim)
SIGPIPE crash fix(Darren)
large object fixes(Sven)
allow btree indexes to handle NULLs(Vadim)
timezone fixes(D’Arcy)
select SUM(x) can return NULL on no rows(Thomas)
internal optimizer, executor bug fixes(Vadim)
fix problem where inner loop in < or <= has no rows(Vadim)
prevent re-commuting join index clauses(Vadim)
fix join clauses for multiple tables(Vadim)
fix hash, hashjoin for arrays(Vadim)
fix btree for abstime type(Vadim)
large object fixes(Raymond)
fix buffer leak in hash indexes (Vadim)
fix rtree for use in inner scan (Vadim)
fix gist for use in inner scan, cleanups (Vadim, Andrea)
avoid unnecessary local buffers allocation (Vadim, Massimo)
fix local buffers leak in transaction aborts (Vadim)
fix file manager memmory leaks, cleanups (Vadim, Massimo)
fix storage manager memmory leaks (Vadim)
fix btree duplicates handling (Vadim)
fix deleted tuples re-incarnation caused by vacuum (Vadim)
fix SELECT varchar()/char() INTO TABLE made zero-length fields(Bruce)
many psql, pg_dump, and libpq memory leaks fixed using Purify (Igor)
Enhancements
------------
attribute optimization statistics(Bruce)
much faster new btree bulk load code(Paul)
BTREE UNIQUE added to bulk load code(Vadim)
new lock debug code(Massimo)
massive changes to libpg++(Leo)
new GEQO optimizer speeds table multitable optimization(Martin)
new WARN message for non-unique insert into unique key(Marc)
update x=-3, no spaces, now valid(Bruce)
remove case-sensitive identifier handling(Bruce,Thomas,Dan)
debug backend now pretty-prints tree(Darren)
new Oracle character functions(Edmund)
new plaintext password functions(Dan)
no such class or insufficient privilege changed to distinct messages(Dan)
new ANSI timestamp function(Dan)
new ANSI Time and Date types (Thomas)
move large chunks of data in backend(Martin)
multicolumn btree indexes(Vadim)
new SET var TO value command(Martin)
update transaction status on reads(Dan)
new locale settings for character types(Oleg)
new SEQUENCE serial number generator(Vadim)
GROUP BY function now possible(Vadim)
re-organize regression test(Thomas,Marc)
new optimizer operation weights(Vadim)
172
Appendix A. Release Notes
new psql \z grant/permit option(Marc)
new MONEY data type(D’Arcy,Thomas)
tcp socket communication speed improved(Vadim)
new VACUUM option for attribute statistics, and for certain columns (Vadim)
many geometric type improvements(Thomas,Keith)
additional regression tests(Thomas)
new datestyle variable(Thomas,Vadim,Martin)
more comparison operators for sorting types(Thomas)
new conversion functions(Thomas)
new more compact btree format(Vadim)
allow pg_dumpall to preserve database ownership(Bruce)
new SET GEQO=# and R_PLANS variable(Vadim)
old (!GEQO) optimizer can use right-sided plans (Vadim)
typechecking improvement in SQL parser(Bruce)
new SET, SHOW, RESET commands(Thomas,Vadim)
new \connect database USER option
new destroydb -i option (Igor)
new \dt and \di psql commands (Darren)
SELECT "\n" now escapes newline (A. Duursma)
new geometry conversion functions from old format (Thomas)
Source tree changes
-------------------
new configuration script(Marc)
readline configuration option added(Marc)
OS-specific configuration options removed(Marc)
new OS-specific template files(Marc)
no more need to edit Makefile.global(Marc)
re-arrange include files(Marc)
nextstep patches (Gregor Hoffleit)
removed WIN32-specific code(Bruce)
removed postmaster -e option, now only postgres -e option (Bruce)
merge duplicate library code in front/backends(Martin)
now works with eBones, international Kerberos(Jun)
more shared library support
c++ include file cleanup(Bruce)
warn about buggy flex(Bruce)
DG/UX, Ultrix, IRIX, AIX portability fixes
A.31. Release 6.0
Release date: 1997-01-29
A dump/restore is required for those wishing to migrate data from previous releases of PostgreSQL.
173
Appendix A. Release Notes
A.31.1. Migration from version 1.09 to version 6.0
This migration requires a complete dump of the 1.09 database and a restore of the database in 6.0.
A.31.2. Migration from pre-1.09 to version 6.0
Those migrating from earlier 1.* releases should first upgrade to 1.09 because the COPY output format
was improved from the 1.02 release.
A.31.3. Changes
Bug Fixes
---------
ALTER TABLE bug - running postgress process needs to re-read table definition
Allow vacuum to be run on one table or entire database(Bruce)
Array fixes
Fix array over-runs of memory writes(Kurt)
Fix elusive btree range/non-range bug(Dan)
Fix for hash indexes on some types like time and date
Fix for pg_log size explosion
Fix permissions on lo_export()(Bruce)
Fix unitialized reads of memory(Kurt)
Fixed ALTER TABLE ... char(3) bug(Bruce)
Fixed a few small memory leaks
Fixed EXPLAIN handling of options and changed full_path option name
Fixed output of group acl permissions
Memory leaks (hunt and destroy with tools like Purify(Kurt)
Minor improvements to rules system
NOTIFY fixes
New asserts for run-checking
Overhauled parser/analyze code to properly report errors and increase speed
Pg_dump -d now handles NULL’s properly(Bruce)
Prevent SELECT NULL from crashing server (Bruce)
Properly report errors when INSERT ... SELECT columns did not match
Properly report errors when insert column names were not correct
Psql \g filename now works(Bruce)
Psql fixed problem with multiple statements on one line with multiple outputs
Removed duplicate system OIDs
SELECT * INTO TABLE . GROUP/ORDER BY gives unlink error if table exists(Bruce)
Several fixes for queries that crashed the backend
Starting quote in insert string errors(Bruce)
Submitting an empty query now returns empty status, not just " " query(Bruce)
Enhancements
------------
Add EXPLAIN manual page(Bruce)
Add UNIQUE index capability(Dan)
Add hostname/user level access control rather than just hostname and user
Add synonym of != for <>(Bruce)
Allow "select oid,* from table"
174
Appendix A. Release Notes
Allow BY,ORDER BY to specify columns by number, or by non-alias table.column(Bruce)
Allow COPY from the frontend(Bryan)
Allow GROUP BY to use alias column name(Bruce)
Allow actual compression, not just reuse on the same page(Vadim)
Allow installation-configuration option to auto-add all local users(Bryan)
Allow libpq to distinguish between text value ” and null(Bruce)
Allow non-postgres users with createdb privs to destroydb’s
Allow restriction on who can create C functions(Bryan)
Allow restriction on who can do backend COPY(Bryan)
Can shrink tables, pg_time and pg_log(Vadim & Erich)
Change debug level 2 to print queries only, changed debug heading layout(Bruce)
Change default decimal constant representation from float4 to float8(Bruce)
European date format now set when postmaster is started
Execute lowercase function names if not found with exact case
Fixes for aggregate/GROUP processing, allow ’select sum(func(x),sum(x+y) from z’
Gist now included in the distrubution(Marc)
Idend authentication of local users(Bryan)
Implement BETWEEN qualifier(Bruce)
Implement IN qualifier(Bruce)
Libpq has PQgetisnull()(Bruce)
Libpq++ improvements
New options to initdb(Bryan)
Pg_dump allow dump of OIDs(Bruce)
Pg_dump create indexes after tables are loaded for speed(Bruce)
Pg_dumpall dumps all databases, and the user table
Pginterface additions for NULL values(Bruce)
Prevent postmaster from being run as root
Psql \h and \? is now readable(Bruce)
Psql allow backslashed, semicolons anywhere on the line(Bruce)
Psql changed command prompt for lines in query or in quotes(Bruce)
Psql char(3) now displays as (bp)char in \d output(Bruce)
Psql return code now more accurate(Bryan?)
Psql updated help syntax(Bruce)
Re-visit and fix vacuum(Vadim)
Reduce size of regression diffs, remove timezone name difference(Bruce)
Remove compile-time parameters to enable binary distributions(Bryan)
Reverse meaning of HBA masks(Bryan)
Secure Authentication of local users(Bryan)
Speed up vacuum(Vadim)
Vacuum now had VERBOSE option(Bruce)
Source tree changes
-------------------
All functions now have prototypes that are compared against the calls
Allow asserts to be disabled easly from Makefile.global(Bruce)
Change oid constants used in code to #define names
Decoupled sparc and solaris defines(Kurt)
Gcc -Wall compiles cleanly with warnings only from unfixable constructs
Major include file reorganization/reduction(Marc)
Make now stops on compile failure(Bryan)
Makefile restructuring(Bryan, Marc)
Merge bsdi_2_1 to bsdi(Bruce)
Monitor program removed
175
Appendix A. Release Notes
Name change from Postgres95 to PostgreSQL
New config.h file(Marc, Bryan)
PG_VERSION now set to 6.0 and used by postmaster
Portability additions, including Ultrix, DG/UX, AIX, and Solaris
Reduced the number of #define’s, centeralized #define’s
Remove duplicate OIDS in system tables(Dan)
Remove duplicate system catalog info or report mismatches(Dan)
Removed many os-specific #define’s
Restructured object file generation/location(Bryan, Marc)
Restructured port-specific file locations(Bryan, Marc)
Unused/uninialized variables corrected
A.32. Release 1.09
Release date: 1996-11-04
Sorry, we didn’t keep track of changes from 1.02 to 1.09. Some of the changes listed in 6.0 were actually
included in the 1.02.1 to 1.09 releases.
A.33. Release 1.02
Release date: 1996-08-01
A.33.1. Migration from version 1.02 to version 1.02.1
Here is a new migration file for 1.02.1. It includes the ’copy’ change and a script to convert old ASCII
files.
Note: The following notes are for the benefit of users who want to migrate databases from Postgres95
1.01 and 1.02 to Postgres95 1.02.1.
If you are starting afresh with Postgres95 1.02.1 and do not need to migrate old databases, you do
not need to read any further.
In order to upgrade older Postgres95 version 1.01 or 1.02 databases to version 1.02.1, the following steps
are required:
1. Start up a new 1.02.1 postmaster
176
Appendix A. Release Notes
2. Add the new built-in functions and operators of 1.02.1 to 1.01 or 1.02 databases. This is done by run-
ning the new 1.02.1 server against your own 1.01 or 1.02 database and applying the queries attached
at the end of the file. This can be done easily through psql. If your 1.01 or 1.02 database is named
testdb and you have cut the commands from the end of this file and saved them in addfunc.sql:
% psql testdb -f addfunc.sql
Those upgrading 1.02 databases will get a warning when executing the last two statements in the file
because they are already present in 1.02. This is not a cause for concern.
A.33.2. Dump/Reload Procedure
If you are trying to reload a pg_dump or text-mode, copy tablename to stdout generated with a
previous version, you will need to run the attached sed script on the ASCII file before loading it into the
database. The old format used ’.’ as end-of-data, while ’\.’ is now the end-of-data marker. Also, empty
strings are now loaded in as ” rather than NULL. See the copy manual page for full details.
sed ’s/^\.$/\\./g’ <in_file >out_file
If you are loading an older binary copy or non-stdout copy, there is no end-of-data character, and hence
no conversion necessary.
-- following lines added by agc to reflect the case-insensitive
-- regexp searching for varchar (in 1.02), and bpchar (in 1.02.1)
create operator ~* (leftarg = bpchar, rightarg = text, procedure = texticregexeq);
create operator !~* (leftarg = bpchar, rightarg = text, procedure = texticregexne);
create operator ~* (leftarg = varchar, rightarg = text, procedure = texticregexeq);
create operator !~* (leftarg = varchar, rightarg = text, procedure = texti-
cregexne);
A.33.3. Changes
Source code maintenance and development
* worldwide team of volunteers
* the source tree now in CVS at ftp.ki.net
Enhancements
* psql (and underlying libpq library) now has many more options for
formatting output, including HTML
* pg_dump now output the schema and/or the data, with many fixes to
enhance completeness.
* psql used in place of monitor in administration shell scripts.
monitor to be deprecated in next release.
* date/time functions enhanced
* NULL insert/update/comparison fixed/enhanced
* TCL/TK lib and shell fixed to work with both tck7.4/tk4.0 and tcl7.5/tk4.1
177
Appendix A. Release Notes
Bug Fixes (almost too numerous to mention)
* indexes
* storage management
* check for NULL pointer before dereferencing
* Makefile fixes
New Ports
* added SolarisX86 port
* added BSD/OS 2.1 port
* added DG/UX port
A.34. Release 1.01
Release date: 1996-02-23
A.34.1. Migration from version 1.0 to version 1.01
The following notes are for the benefit of users who want to migrate databases from Postgres95 1.0 to
Postgres95 1.01.
If you are starting afresh with Postgres95 1.01 and do not need to migrate old databases, you do not need
to read any further.
In order to Postgres95 version 1.01 with databases created with Postgres95 version 1.0, the following
steps are required:
1. Set the definition of NAMEDATALEN in src/Makefile.global to 16 and OIDNAMELEN to 20.
2. Decide whether you want to use Host based authentication.
a. If you do, you must create a file name pg_hba in your top-level data directory (typically the
value of your $PGDATA). src/libpq/pg_hba shows an example syntax.
b. If you do not want host-based authentication, you can comment out the line
HBA = 1
in src/Makefile.global
Note that host-based authentication is turned on by default, and if you do not take steps A
or B above, the out-of-the-box 1.01 will not allow you to connect to 1.0 databases.
3. Compile and install 1.01, but DO NOT do the initdb step.
4. Before doing anything else, terminate your 1.0 postmaster, and backup your existing $PGDATA direc-
tory.
5. Set your PGDATA environment variable to your 1.0 databases, but set up path up so that 1.01 binaries
are being used.
178
Appendix A. Release Notes
6. Modify the file $PGDATA/PG_VERSION from 5.0 to 5.1
7. Start up a new 1.01 postmaster
8. Add the new built-in functions and operators of 1.01 to 1.0 databases. This is done by running the
new 1.01 server against your own 1.0 database and applying the queries attached and saving in the
file 1.0_to_1.01.sql. This can be done easily through psql. If your 1.0 database is name testdb:
% psql testdb -f 1.0_to_1.01.sql
and then execute the following commands (cut and paste from here):
-- add builtin functions that are new to 1.01
create function int4eqoid (int4, oid) returns bool as ’foo’
language ’internal’;
create function oideqint4 (oid, int4) returns bool as ’foo’
language ’internal’;
create function char2icregexeq (char2, text) returns bool as ’foo’
language ’internal’;
create function char2icregexne (char2, text) returns bool as ’foo’
language ’internal’;
create function char4icregexeq (char4, text) returns bool as ’foo’
language ’internal’;
create function char4icregexne (char4, text) returns bool as ’foo’
language ’internal’;
create function char8icregexeq (char8, text) returns bool as ’foo’
language ’internal’;
create function char8icregexne (char8, text) returns bool as ’foo’
language ’internal’;
create function char16icregexeq (char16, text) returns bool as ’foo’
language ’internal’;
create function char16icregexne (char16, text) returns bool as ’foo’
language ’internal’;
create function texticregexeq (text, text) returns bool as ’foo’
language ’internal’;
create function texticregexne (text, text) returns bool as ’foo’
language ’internal’;
-- add builtin functions that are new to 1.01
create operator = (leftarg = int4, rightarg = oid, procedure = int4eqoid);
create operator = (leftarg = oid, rightarg = int4, procedure = oideqint4);
create operator ~* (leftarg = char2, rightarg = text, procedure = char2icregexeq);
create operator !~* (leftarg = char2, rightarg = text, procedure = char2icregexne);
create operator ~* (leftarg = char4, rightarg = text, procedure = char4icregexeq);
create operator !~* (leftarg = char4, rightarg = text, procedure = char4icregexne);
create operator ~* (leftarg = char8, rightarg = text, procedure = char8icregexeq);
create operator !~* (leftarg = char8, rightarg = text, procedure = char8icregexne);
create operator ~* (leftarg = char16, rightarg = text, procedure = char16icregexeq);
create operator !~* (leftarg = char16, rightarg = text, procedure = char16icregexne);
create operator ~* (leftarg = text, rightarg = text, procedure = texticregexeq);
create operator !~* (leftarg = text, rightarg = text, procedure = texti-
cregexne);
179
Appendix A. Release Notes
A.34.2. Changes
Incompatibilities:
* 1.01 is backwards compatible with 1.0 database provided the user
follow the steps outlined in the MIGRATION_from_1.0_to_1.01 file.
If those steps are not taken, 1.01 is not compatible with 1.0 database.
Enhancements:
* added PQdisplayTuples() to libpq and changed monitor and psql to use it
* added NeXT port (requires SysVIPC implementation)
* added CAST .. AS ... syntax
* added ASC and DESC keywords
* added ’internal’ as a possible language for CREATE FUNCTION
internal functions are C functions which have been statically linked
into the postgres backend.
* a new type "name" has been added for system identifiers (table names,
attribute names, etc.) This replaces the old char16 type. The
of name is set by the NAMEDATALEN #define in src/Makefile.global
* a readable reference manual that describes the query language.
* added host-based access control. A configuration file ($PGDATA/pg_hba)
is used to hold the configuration data. If host-based access control
is not desired, comment out HBA=1 in src/Makefile.global.
* changed regex handling to be uniform use of Henry Spencer’s regex code
regardless of platform. The regex code is included in the distribution
* added functions and operators for case-insensitive regular expressions.
The operators are ~* and !~*.
* pg_dump uses COPY instead of SELECT loop for better performance
Bug fixes:
* fixed an optimizer bug that was causing core dumps when
functions calls were used in comparisons in the WHERE clause
* changed all uses of getuid to geteuid so that effective uids are used
* psql now returns non-zero status on errors when using -c
* applied public patches 1-14
A.35. Release 1.0
Release date: 1995-09-05
A.35.1. Changes
Copyright change:
* The copyright of Postgres 1.0 has been loosened to be freely modifiable
and modifiable for any purpose. Please read the COPYRIGHT file.
Thanks to Professor Michael Stonebraker for making this possible.
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Appendix A. Release Notes
Incompatibilities:
* date formats have to be MM-DD-YYYY (or DD-MM-YYYY if you’re using
EUROPEAN STYLE). This follows SQL-92 specs.
* "delimiters" is now a keyword
Enhancements:
* sql LIKE syntax has been added
* copy command now takes an optional USING DELIMITER specification.
delimiters can be any single-character string.
* IRIX 5.3 port has been added.
Thanks to Paul Walmsley and others.
* updated pg_dump to work with new libpq
* \d has been added psql
Thanks to Keith Parks
* regexp performance for architectures that use POSIX regex has been
improved due to caching of precompiled patterns.
Thanks to Alistair Crooks
* a new version of libpq++
Thanks to William Wanders
Bug fixes:
* arbitrary userids can be specified in the createuser script
* \c to connect to other databases in psql now works.
* bad pg_proc entry for float4inc() is fixed
* users with usecreatedb field set can now create databases without
having to be usesuper
* remove access control entries when the entry no longer has any
permissions
* fixed non-portable datetimes implementation
* added kerberos flags to the src/backend/Makefile
* libpq now works with kerberos
* typographic errors in the user manual have been corrected.
* btrees with multiple index never worked, now we tell you they don’t
work when you try to use them
A.36. Postgres95 Release 0.03
Release date: 1995-07-21
A.36.1. Changes
Incompatible changes:
* BETA-0.3 IS INCOMPATIBLE WITH DATABASES CREATED WITH PREVIOUS VERSIONS
(due to system catalog changes and indexing structure changes).
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Appendix A. Release Notes
* double-quote (") is deprecated as a quoting character for string literals;
you need to convert them to single quotes (’).
* name of aggregates (eg. int4sum) are renamed in accordance with the
SQL standard (eg. sum).
* CHANGE ACL syntax is replaced by GRANT/REVOKE syntax.
* float literals (eg. 3.14) are now of type float4 (instead of float8 in
previous releases); you might have to do typecasting if you depend on it
being of type float8. If you neglect to do the typecasting and you assign
a float literal to a field of type float8, you may get incorrect values
stored!
* LIBPQ has been totally revamped so that frontend applications
can connect to multiple backends
* the usesysid field in pg_user has been changed from int2 to int4 to
allow wider range of Unix user ids.
* the netbsd/freebsd/bsd o/s ports have been consolidated into a
single BSD44_derived port. (thanks to Alistair Crooks)
SQL standard-compliance (the following details changes that makes postgres95
more compliant to the SQL-92 standard):
* the following SQL types are now built-in: smallint, int(eger), float, real,
char(N), varchar(N), date and time.
The following are aliases to existing postgres types:
smallint -> int2
integer, int -> int4
float, real -> float4
char(N) and varchar(N) are implemented as truncated text types. In
addition, char(N) does blank-padding.
* single-quote (’) is used for quoting string literals; ” (in addition to
\’) is supported as means of inserting a single quote in a string
* SQL standard aggregate names (MAX, MIN, AVG, SUM, COUNT) are used
(Also, aggregates can now be overloaded, i.e. you can define your
own MAX aggregate to take in a user-defined type.)
* CHANGE ACL removed. GRANT/REVOKE syntax added.
- Privileges can be given to a group using the "GROUP" keyword.
For example:
GRANT SELECT ON foobar TO GROUP my_group;
The keyword ’PUBLIC’ is also supported to mean all users.
Privileges can only be granted or revoked to one user or group
at a time.
"WITH GRANT OPTION" is not supported. Only class owners can change
access control
- The default access control is to to grant users readonly access.
You must explicitly grant insert/update access to users. To change
this, modify the line in
src/backend/utils/acl.h
that defines ACL_WORLD_DEFAULT
Bug fixes:
* the bug where aggregates of empty tables were not run has been fixed. Now,
aggregates run on empty tables will return the initial conditions of the
182
Appendix A. Release Notes
aggregates. Thus, COUNT of an empty table will now properly return 0.
MAX/MIN of an empty table will return a tuple of value NULL.
* allow the use of \; inside the monitor
* the LISTEN/NOTIFY asynchronous notification mechanism now work
* NOTIFY in rule action bodies now work
* hash indexes work, and access methods in general should perform better.
creation of large btree indexes should be much faster. (thanks to Paul
Aoki)
Other changes and enhancements:
* addition of an EXPLAIN statement used for explaining the query execution
plan (eg. "EXPLAIN SELECT * FROM EMP" prints out the execution plan for
the query).
* WARN and NOTICE messages no longer have timestamps on them. To turn on
timestamps of error messages, uncomment the line in
src/backend/utils/elog.h:
/* define ELOG_TIMESTAMPS */
* On an access control violation, the message
"Either no such class or insufficient privilege"
will be given. This is the same message that is returned when
a class is not found. This dissuades non-privileged users from
guessing the existence of privileged classes.
* some additional system catalog changes have been made that are not
visible to the user.
libpgtcl changes:
* The -oid option has been added to the "pg_result" tcl command.
pg_result -oid returns oid of the last tuple inserted. If the
last command was not an INSERT, then pg_result -oid returns "".
* the large object interface is available as pg_lo* tcl commands:
pg_lo_open, pg_lo_close, pg_lo_creat, etc.
Portability enhancements and New Ports:
* flex/lex problems have been cleared up. Now, you should be able to use
flex instead of lex on any platforms. We no longer make assumptions of
what lexer you use based on the platform you use.
* The Linux-ELF port is now supported. Various configuration have been
tested: The following configuration is known to work:
kernel 1.2.10, gcc 2.6.3, libc 4.7.2, flex 2.5.2, bison 1.24
with everything in ELF format,
New utilities:
* ipcclean added to the distribution
ipcclean usually does not need to be run, but if your backend crashes
and leaves shared memory segments hanging around, ipcclean will
clean them up for you.
New documentation:
* the user manual has been revised and libpq documentation added.
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Appendix A. Release Notes
A.37. Postgres95 Release 0.02
Release date: 1995-05-25
A.37.1. Changes
Incompatible changes:
* The SQL statement for creating a database is ’CREATE DATABASE’ instead
of ’CREATEDB’. Similarly, dropping a database is ’DROP DATABASE’ instead
of ’DESTROYDB’. However, the names of the executables ’createdb’ and
’destroydb’ remain the same.
New tools:
* pgperl - a Perl (4.036) interface to Postgres95
* pg_dump - a utility for dumping out a postgres database into a
script file containing query commands. The script files are in a ASCII
format and can be used to reconstruct the database, even on other
machines and other architectures. (Also good for converting
a Postgres 4.2 database to Postgres95 database.)
The following ports have been incorporated into postgres95-beta-0.02:
* the NetBSD port by Alistair Crooks
* the AIX port by Mike Tung
* the Windows NT port by Jon Forrest (more stuff but not done yet)
* the Linux ELF port by Brian Gallew
The following bugs have been fixed in postgres95-beta-0.02:
* new lines not escaped in COPY OUT and problem with COPY OUT when first
attribute is a ’.’
* cannot type return to use the default user id in createuser
* SELECT DISTINCT on big tables crashes
* Linux installation problems
* monitor doesn’t allow use of ’localhost’ as PGHOST
* psql core dumps when doing \c or \l
* the "pgtclsh" target missing from src/bin/pgtclsh/Makefile
* libpgtcl has a hard-wired default port number
* SELECT DISTINCT INTO TABLE hangs
* CREATE TYPE doesn’t accept ’variable’ as the internallength
* wrong result using more than 1 aggregate in a SELECT
A.38. Postgres95 Release 0.01
Release date: 1995-05-01
184
Appendix A. Release Notes
Initial release.
185
Bibliography
Selected references and readings for SQL and PostgreSQL.
Some white papers and technical reports from the original POSTGRES development team are available at
the University of California, Berkeley, Computer Science Department web site
1
SQL Reference Books
Judith Bowman, Sandra Emerson, and Marcy Darnovsky, The Practical SQL Handbook: Using Structured
Query Language, Third Edition, Addison-Wesley, ISBN 0-201-44787-8, 1996.
C. J. Date and Hugh Darwen, A Guide to the SQL Standard: A user’s guide to the standard database
language SQL, Fourth Edition, Addison-Wesley, ISBN 0-201-96426-0, 1997.
C. J. Date, An Introduction to Database Systems, Volume 1, Sixth Edition, Addison-Wesley, 1994.
Ramez Elmasri and Shamkant Navathe, Fundamentals of Database Systems, 3rd Edition,
Addison-Wesley, ISBN 0-805-31755-4, August 1999.
Jim Melton and Alan R. Simon, Understanding the New SQL: A complete guide, Morgan Kaufmann,
ISBN 1-55860-245-3, 1993.
Jeffrey D. Ullman, Principles of Database and Knowledge: Base Systems, Volume 1, Computer Science
Press, 1988.
PostgreSQL-Specific Documentation
Stefan Simkovics, Enhancement of the ANSI SQL Implementation of PostgreSQL, Department of Infor-
mation Systems, Vienna University of Technology, November 29, 1998.
Discusses SQL history and syntax, and describes the addition of INTERSECT and EXCEPT constructs
into PostgreSQL. Prepared as a Master’s Thesis with the support of O. Univ. Prof. Dr. Georg Gottlob
and Univ. Ass. Mag. Katrin Seyr at Vienna University of Technology.
A. Yu and J. Chen, The POSTGRES Group, The Postgres95 User Manual, University of California, Sept.
5, 1995.
Zelaine Fong, The design and implementation of the POSTGRES query optimizer
2
, University of Califor-
nia, Berkeley, Computer Science Department.
1. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/
2. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/UCB-MS-zfong.pdf
186
Bibliography
Proceedings and Articles
Nels Olson, Partial indexing in POSTGRES: research project, University of California, UCB Engin
T7.49.1993 O676, 1993.
L. Ong and J. Goh, “A Unified Framework for Version Modeling Using Production Rules in a Database
System”, ERL Technical Memorandum M90/33, University of California, April, 1990.
L. Rowe and M. Stonebraker, “The POSTGRES data model
3
”, Proc. VLDB Conference, Sept. 1987.
P. Seshadri and A. Swami, “Generalized Partial Indexes
4
”, Proc. Eleventh International Conference on
Data Engineering, 6-10 March 1995, IEEE Computer Society Press, Cat. No.95CH35724, 1995, p.
420-7.
M. Stonebraker and L. Rowe, “The design of POSTGRES
5
”, Proc. ACM-SIGMOD Conference on Man-
agement of Data, May 1986.
M. Stonebraker, E. Hanson, and C. H. Hong, “The design of the POSTGRES rules system”, Proc. IEEE
Conference on Data Engineering, Feb. 1987.
M. Stonebraker, “The design of the POSTGRES storage system
6
”, Proc. VLDB Conference, Sept. 1987.
M. Stonebraker, M. Hearst, and S. Potamianos, “A commentary on the POSTGRES rules system
7
”, SIG-
MOD Record 18(3), Sept. 1989.
M. Stonebraker, “The case for partial indexes
8
”, SIGMOD Record 18(4), Dec. 1989, p. 4-11.
M. Stonebraker, L. A. Rowe, and M. Hirohama, “The implementation of POSTGRES
9
”, Transactions on
Knowledge and Data Engineering 2(1), IEEE, March 1990.
M. Stonebraker, A. Jhingran, J. Goh, and S. Potamianos, “On Rules, Procedures, Caching and Views in
Database Systems
10
”, Proc. ACM-SIGMOD Conference on Management of Data, June 1990.
3. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M87-13.pdf
4. http://simon.cs.cornell.edu/home/praveen/papers/partindex.de95.ps.Z
5. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M85-95.pdf
6. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M87-06.pdf
7. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M89-82.pdf
8. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M89-17.pdf
9. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M90-34.pdf
10. http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M90-36.pdf
187
Index
Symbols
$libdir, ?
A
aggregate, ?
aggregate functions, ?
extending, ?
alias
(See label)
for table name in query, ?
all, ?
and
operator, ?
any, ?, ?
anyarray, ?
arrays, ?, ?
constants, ?
Australian time zones, ?
auto-increment
(See serial)
autocommit, ?
average, 1
function, ?
B
B-tree
(See indexes)
backup, 82
between, ?
bigint, ?
bigserial, ?
binary strings
concatenation, ?
length, ?
bison, ?
bit strings
constants, ?
data type, ?
BLOB
(See large object)
Boolean
data type, ?
operators
(See operators, logical)
box (data type), ?
BSD/OS, ?, ?
C
case, ?
case sensitivity
SQL commands, ?
catalogs, ?
character set encoding, ?
character strings
concatenation, ?
constants, ?
data types, ?
length, ?
cid, ?
cidr, ?
circle, ?
client authentication, 55
cluster, ?
column, ?
columns
system columns, 21
col_description, ?
comments
in SQL, ?
comparison
operators, ?
concurrency, ?
conditionals, ?
configuration
server, ?
configure, 5
connection loss, ?
constants, ?
COPY, ?
with libpq, ?
count, ?
CREATE TABLE, ?
createdb, ?
crypt, ?
cstring, ?
currval, ?
188
Index
D
data area
(See database cluster)
data types, ?, ?
constants, ?
extending, ?
numeric, ?
type casts, ?
database, 50
creating, ?
database cluster, ?
date
constants, ?
current, ?
data type, ?
output format, ?
(See Also Formatting)
date style, ?
deadlock
timeout, ?
decimal
(See numeric)
DELETE, ?
Digital UNIX
(See Tru64 UNIX)
dirty read, ?
disk space, 77
disk usage, 95
DISTINCT, ?, ?
double precision, ?
DROP TABLE, ?
duplicate, ?
dynamic loading, ?
dynamic_library_path, ?, ?
E
elog, ?
PL/Perl, ?
embedded SQL
in C, ?
environment variables, ?
error message, ?
escaping binary strings, ?
escaping strings, ?
except, ?
exists, ?
extending SQL, ?
types, ?
F
false, ?
FETCH
embedded SQL, ?
files, ?
flex, ?
float4
(See real)
float8
(See double precision)
floating point, ?
foreign key, ?
formatting, ?
FreeBSD, ?, ?, ?
fsync, ?
function, ?, ?
internal, ?
SQL, ?
functions, ?
G
genetic query optimization, ?
GEQO
(See genetic query optimization)
get_bit, ?
get_byte, ?
group, ?
GROUP BY, ?
H
hash
(See indexes)
has_database_privilege, ?
has_function_privilege, ?
has_language_privilege, ?
has_schema_privilege, ?
has_table_privilege, ?
HAVING, ?
hierarchical database, ?
HP-UX, ?, ?
189
Index
I
ident, ?
identifiers, ?
in, ?
index scan, ?
indexes, ?
B-tree, ?
hash, ?
multicolumn, ?
on functions, ?
partial, ?
R-tree, ?
unique, ?
inet (data type), ?
inheritance, ?, ?
initlocation, ?
input function, ?
INSERT, ?
installation, 1
on Windows, ?, ?
int2
(See smallint)
int4
(See integer)
int8
(See bigint)
integer, ?
internal, ?
intersection, ?
interval, ?
IRIX, ?
IS NULL, ?
isolation levels, ?
read committed, ?
read serializable, ?
J
join, ?
outer, ?
self, ?
joins, ?
cross, ?
left, ?
natural, ?
outer, ?
K
Kerberos, 60
key words
list of, ?
syntax, ?
L
label
column, ?
table, ?
language_handler, ?
large object, ?
LC_COLLATE, ?
ldconfig, ?
length
binary strings
(See binary strings, length)
character strings
(See character strings, length)
libperl, ?
libpgtcl, ?
libpq, ?
libpq-fe.h, ?
libpq-int.h, ?, ?
libpython, ?
like, ?
limit, ?
line, ?
Linux, ?, ?, ?
locale, ?, 65
locking, ?
log files, 81
M
MAC address
(See macaddr)
macaddr (data type), ?
MacOS X, ?, ?
make, ?
MANPATH, ?
(See Also man pages)
max, ?
MD5, ?
190
Index
min, ?
multibyte, 68
N
names
qualified, ?
unqualified, ?
namespaces, ?, ?
NetBSD, ?, ?, ?
network
addresses, ?
nextval, ?
nonblocking connection, ?, ?
nonrepeatable read, ?
not
operator, ?
not in, ?
notice processor, ?
NOTIFY, ?, ?
nullif, ?
numeric
constants, ?
numeric (data type), ?
O
object identifier
data type, ?
object-oriented database, ?
obj_description, ?
offset
with query results, ?
OID, ?, ?
opaque, ?
OpenBSD, ?, ?, ?
OpenSSL, ?
(See Also SSL)
operators, ?
logical, ?
precedence, ?
syntax, ?
or
operator, ?
Oracle, ?, ?
ORDER BY, ?, ?
output function, ?
overlay, ?
overloading, ?
P
password, ?
.pgpass, ?
PATH, ?
path (data type), ?
Perl, ?
PGDATA, ?
PGDATABASE, ?
PGHOST, ?
PGPASSWORD, ?
PGPORT, ?
pgtcl
closing, ?
connecting, ?, ?, ?, ?, ?, ?
connection loss, ?
creating, ?
delete, ?
export, ?
import, ?
notify, ?
opening, ?
positioning, ?, ?
query, ?
reading, ?
writing, ?
PGUSER, ?
pg_config, ?, ?
pg_conndefaults, ?
pg_connect, ?, ?, ?, ?, ?
pg_ctl, ?
pg_dumpall, ?
pg_execute, ?
pg_function_is_visible, ?
pg_get_constraintdef, ?
pg_get_indexdef, ?
pg_get_ruledef, ?
pg_get_userbyid, ?
pg_get_viewdef, ?
pg_hba.conf, 55
pg_ident.conf, ?
pg_lo_close, ?
pg_lo_creat, ?
pg_lo_export, ?
191
Index
pg_lo_import, ?
pg_lo_lseek, ?
pg_lo_open, ?
pg_lo_read, ?
pg_lo_tell, ?
pg_lo_unlink, ?
pg_lo_write, ?
pg_opclass_is_visible, ?
pg_operator_is_visible, ?
pg_table_is_visible, ?
pg_type_is_visible, ?
phantom read, ?
PIC, ?
PL/Perl, ?
PL/pgSQL, ?
PL/Python, ?
PL/SQL, ?
PL/Tcl, ?
point, ?
polygon, ?
port, ?
postgres user, ?
postmaster, ?, ?
ps
to monitor activity, 87
psql, ?
Python, ?
Q
qualified names, ?
query, ?
quotes
and identifiers, ?
escaping, ?
R
R-tree
(See indexes)
range table, ?
readline, ?
real, ?
record, ?
referential integrity, ?
regclass, ?
regoper, ?
regoperator, ?
regproc, ?
regprocedure, ?
regression test, ?
regtype, ?
regular expressions, ?, ?
(See Also pattern matching)
reindex, 80
relation, ?
relational database, ?
row, ?
rules, ?
and views, ?
S
schema
current, ?
schemas, ?
current schema, ?
SCO OpenServer, ?
search path, ?
changing at runtime, ?
current, ?
search_path, ?
SELECT, ?
select list, ?
semaphores, 38
sequences, ?
and serial type, ?
sequential scan, ?
serial, ?
serial4, ?
serial8, ?
SETOF, ?
(See Also function)
setting
current, ?
set, ?
setval, ?
set_bit, ?
set_byte, ?
shared libraries, ?
shared memory, 38
SHMMAX, ?
SIGHUP, ?, ?, ?
similar to, ?
192
Index
sliced bread
(See TOAST)
smallint, ?
Solaris, ?, ?, ?
some, ?
sorting
query results, ?
SPI
allocating space, ?, ?, ?, ?, ?, ?
connecting, ?, ?, ?, ?
copying tuple descriptors, ?
copying tuples, ?, ?
cursors, ?, ?, ?, ?, ?
decoding tuples, ?, ?, ?, ?, ?, ?, ?
disconnecting, ?
executing, ?
modifying tuples, ?
SPI_connect, ?
SPI_copytuple, ?
SPI_copytupledesc, ?
SPI_copytupleintoslot, ?
SPI_cursor_close, ?
SPI_cursor_fetch, ?
SPI_cursor_find, ?
SPI_cursor_move, ?
SPI_cursor_open, ?
SPI_exec, ?
SPI_execp, ?
SPI_finish, ?
SPI_fname, ?
SPI_fnumber, ?
SPI_freeplan, ?
SPI_freetuple, ?
SPI_freetuptable, ?
SPI_getbinval, ?
SPI_getrelname, ?
SPI_gettype, ?
SPI_gettypeid, ?
SPI_getvalue, ?
spi_lastoid, ?
SPI_modifytuple, ?
SPI_palloc, ?
SPI_pfree, ?
SPI_prepare, ?
SPI_repalloc, ?
SPI_saveplan, ?
ssh, 45
SSL, ?, 44, ?
standard deviation, ?
statistics, 88
strings
(See character strings)
subqueries, ?, ?
subquery, ?
substring, ?, ?, ?
sum, ?
superuser, ?
syntax
SQL, ?
T
table, ?
Tcl, ?, ?
TCP/IP, ?
text
(See character strings)
threads
with libpq, ?
tid, ?
time
constants, ?
current, ?
data type, ?
output format, ?
(See Also Formatting)
time with time zone
data type, ?
time without time zone
time, ?
time zone, ?
time zones, ?, ?
timeout
authentication, ?
deadlock, ?
timestamp
data type, ?
timestamp with time zone
data type, ?
timestamp without time zone
data type, ?
timezone
conversion, ?
TOAST, ?
and user-defined types, ?
193
Index
transaction ID
wraparound, 79
transaction isolation level, ?
transactions, ?
trigger, ?
triggers
in PL/Tcl, ?
Tru64 UNIX, ?
true, ?
types
(See data types)
U
union, ?
UnixWare, ?, ?
unqualified names, ?
UPDATE, ?
upgrading, 4, 85
user
current, ?
V
vacuum, 77
variance, ?
version, ?, ?
view, ?
views
updating, ?
void, ?
W
where, ?
X
xid, ?
Y
yacc, ?
194
