This document is the user manual for the PostgreSQL database management system, originally developed at the University of California at Berkeley. PostgreSQL is based on Postgres release 4.2. The Postgres project, led by Professor Michael Stonebraker, has been sponsored by the Defense Advanced Research Projects Agency (DARPA), the Army Research Office (ARO), the National Science Foundation (NSF), and ESL, Inc. Traditional relational database management systems (DBMSs) support a data model consisting 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, as mentioned, this simplicity often makes the implementation of certain applications very difficult. Postgres offers substantial additional power by incorporating the following four additional basic concepts in such a way that users can easily extend the system: classes inheritance types functions Other features provide additional power and flexibility: constraints triggers rules transaction integrity These features put Postgres 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 supporting the traditional relational database languages. So, although Postgres has some object-oriented features, it is firmly in the relational database world. In fact, some commercial databases have recently incorporated features pioneered by Postgres. Implementation of the Postgres DBMS began in 1986. The initial concepts for the system were presented in [STON86] and the definition of the initial data model appeared in [ROWE87]. The design of the rule system at that time was described in [STON87a]. The rationale and architecture of the storage manager were detailed in [STON87b]. Postgres has undergone several major releases since then. The first "demoware" system became operational in 1987 and was shown at the 1988 ACM-SIGMOD Conference. We released Version 1, described in [STON90a], to a few external users in June 1989. In response to a critique of the first rule system ([STON89]), the rule system was redesigned ([STON90b]) 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, releases since then have focused on portability and reliability. Postgres has been used to implement many different research and production applications. These include: 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 picked up the code and commercialized it. Postgres became the primary data manager for the Sequoia 2000 scientific computing project in late 1992. Furthermore, 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 project officially ended with Version 4.2. In 1994, Andrew Yu and Jolly Chen added a SQL language interpreter to Postgres, and the code was subsequently released to the Web to find its own way in the world. Postgres95 was a public-domain, open source descendant of this original Berkeley code. Postgres95 is a derivative of the last official release of Postgres (version 4.2). The code is now completely ANSI C and the code size has been trimmed by 25%. There are a lot of internal changes that improve performance and code maintainability. Postgres95 v1.0.x runs about 30-50% faster on the Wisconsin Benchmark compared to v4.2. Apart from bug fixes, these are the major enhancements: The query language Postquel has been replaced with SQL (implemented in the server). We do not yet support subqueries (which can be imitated with user defined SQL functions). Aggregates have been re-implemented. We also added support for ``GROUP BY''. The libpq interface is still available for C programs. In addition to the monitor program, we provide a new program (psql) which supports GNU readline. We added a new front-end library, libpgtcl, that supports Tcl-based clients. A sample shell, pgtclsh, provides new Tcl commands to interface tcl programs with the Postgres95 backend. The large object interface has been overhauled. We kept Inversion large objects as the only mechanism for storing large objects. (This is not to be confused with the Inversion file system which has been removed.) The instance-level rule system has been removed. Rules are still available as rewrite rules. A short tutorial introducing regular SQL features as well as those of ours is distributed with the source code. GNU make (instead of BSD make) is used for the build. Also, Postgres95 can be compiled with an unpatched gcc (data alignment of doubles has been fixed). By 1996, it became clear that the name Postgres95 would not stand the test of time. A new name, PostgreSQL, was chosen to reflect the relationship between original Postgres and the more recent versions with SQL capability. At the same time, the version numbering was reset to start at 6.0, putting the numbers back into the sequence originally begun by the Postgres Project. The emphasis on development for the v1.0.x releases of Postgres95 was on stabilizing the backend code. With the v6.x series of PostgreSQL, the emphasis has shifted from identifying and understanding existing problems in the backend to augmenting features and capabilities, although work continues in all areas. Major enhancements include: Important backend features, including subselects, defaults, constraints, and triggers, have been implemented. Additional SQL92-compliant language features have been added, including primary keys, quoted identifiers, literal string type coersion, 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%, and backend startup speed has decreased 80%. From now on, We will use Postgres to mean PostgreSQL. PostgreSQL is available without cost. This manual describes version 6.3 of PostgreSQL. Check the Administrator's Guide for a list of currently supported machines. In general, PostgreSQL is portable to any Unix/Posix-compatible system with full libc library support. This manual set is organized into several parts: Tutorial An introduction for new users. Does not cover advanced features. User's Guide General information for users, including available commands and data types. Programmer's Guide Advanced information for application programmers. Topics include type and function extensibility, library interfaces, and application design issues. Administrator's Guide Installation and management information. List of supported machines. Developer's Guide Information for Postgres developers. This is intended for those who are contributing to the Postgres project; application development information should appear in the Programmer's Guide. Reference Manual Detailed reference information on command syntax. At the moment, this manual is very sparse, but eventually should contain information similar to that in the man pages. In addition to this manual set, there are other resources to help you with Postgres installation and use: man pages The man pages have general information on command syntax. FAQs The Frequently Asked Questions (FAQ) documents address both general issues and some platform-specific issues. READMEs README files are available for some contributed packages. Web Site The Postgres web site has some information not appearing in the distribution. There is a mhonarc catalog of mailing list traffic which is a rich resource for many topics. Mailing Lists The Postgres Questions mailing list is a good place to have user questions answered. Other mailing lists are available; consult the web page for details. Yourself! Postgres is an open source product. As such, it depends on the user community for ongoing support. As you begin to use Postgres, 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 it. Even those without a lot of experience can provide corrections and minor changes in the documentation, and that is a good way to start. The Postgres Documentation mailing list is the place to get going. PostgreSQL is copyright (C) 1996-8 by the PostgreSQL Global Development Group, and is distributed under the terms of the Berkeley license. Postgres95 is copyright (C) 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, incidental, 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 implied warranties of merchantability and fitness for a particular purpose. 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