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1. INTRODUCTION
+
+ This document is the user manual for the
+
POSTGRES95
+ database management system developed at the University
+ of California at Berkeley.
POSTGRES95 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.
+
1.1. What is POSTGRES?
+ 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
+ to implement. POSTGRES offers substantial additional
+ power by incorporating the following four additional
+ basic constructs in such a way that users can easily
+ extend the system:
+
+
classes
+ inheritance
+ types
+ functions
+
+ In addition, POSTGRES supports a powerful production
+ rule system.
+
+
+ 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.
+
+
+
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 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 support
+ subqueries (which can be imitated with user defined
+ SQL functions) at the moment. 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).
+
+
+
+
POSTGRES95 is available free of charge. This manual
+ describes version 1.0 of
POSTGRES95. The authors have
+ compiled and tested
POSTGRES95 on the following
+ platforms:
+
+
+
+
+ | Architecture |
+ Processor |
+ Operating System |
+
+
+ | DECstation 3000 |
+ Alpha AXP |
+ OSF/1 2.1, 3.0, 3.2 |
+
+
+ | DECstation 5000 |
+ MIPS |
+ ULTRIX 4.4 |
+
+
+ | Sun4 |
+ SPARC |
+ SunOS 4.1.3, 4.1.3_U1; Solaris 2.4 |
+
+
+ | H-P 9000/700 and 800 |
+ PA-RISC |
+ HP-UX 9.00, 9.01, 9.03 |
+
+
+ | Intel |
+ X86 |
+ Linux 1.2.8, ELF |
+
+
+
+
+ From now on, We will use POSTGRES to mean
POSTGRES95.
+ The first part of this manual goes over some basic sys-
+ tem concepts and procedures for starting the POSTGRES
+ system. We then turn to a tutorial overview of the
+ POSTGRES data model and SQL query language, introducing
+ a few of its advanced features. Next, we explain the
+ POSTGRES approach to extensibility and describe how
+ users can extend POSTGRES by adding user-defined types,
+ operators, aggregates, and both query language and pro-
+ gramming language functions. After an extremely brief
+ overview of the POSTGRES rule system, the manual
+ concludes with a detailed appendix that discusses some of
+ the more involved and operating system-specific
+ procedures involved in extending the system.
+
+
UNIX is a trademark of X/Open, Ltd. Sun4, SPARC, SunOS
+and Solaris are trademarks of Sun Microsystems, Inc. DEC,
+DECstation, Alpha AXP and ULTRIX are trademarks of Digital
+Equipment Corp. PA-RISC and HP-UX are trademarks of
+Hewlett-Packard Co. OSF/1 is a trademark of the Open
+Software Foundation.
+
+ We assume proficiency with UNIX and C programming.
+
+
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