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<TITLE>The POSTGRES95 User Manual - Introduction</TITLE>
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<H1>1. INTRODUCTION</H1>
<HR>
This document is the user manual for the
<A HREF="http://s2k-ftp.cs.berkeley.edu:8000/postgres95/"><B>POSTGRES95</B></A>
database management system developed at the University
of California at Berkeley. <B>POSTGRES95</B> is based on
<A HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/postgres.html">
<B>POSTGRES release 4.2</B></A>. 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.
<H2>1.1. What is POSTGRES?</H2>
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:
<p>
<PRE> classes
inheritance
types
functions
</PRE><p>
In addition, POSTGRES supports a powerful production
rule system.
<H2><A NAME="a-short-history-of-the-postgres-project">1.2. A Short History of the POSTGRES Project</A></H2>
Implementation of the POSTGRES DBMS began in 1986. The
initial concepts for the system were presented in
<A HREF="refs.html#STON86">[STON86]</A> and the definition of the initial data model
appeared in <A HREF="refs.html#ROW87">[ROWE87]</A>. The design of the rule system at
that time was described in <A HREF="refs.html#STON87a">[STON87a]</A>. The rationale
and architecture of the storage manager were detailed
in <A HREF="refs.html#STON87b">[STON87b]</A>.
POSTGRES has undergone several major releases since
then. The first "demoware" system became operational
in 1987 and was shown at the 1988 <B>ACM-SIGMOD</B>
Conference. We released Version 1, described in <A HREF="refs.html#STON90a">[STON90a]</A>,
to a few external users in June 1989. In response to a
critique of the first rule system <A HREF="refs.html#STON89">[STON89]</A>, the rule
system was redesigned <A HREF="refs.html#STON90">[STON90b]</A> 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, <A HREF="http://www.illustra.com/">Illustra Information Technologies</A> picked up
the code and commercialized it.
POSTGRES became the primary data manager for the
<A HREF="http://www.sdsc.edu/0/Parts_Collabs/S2K/s2k_home.html">Sequoia 2000</A> 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 <B>Version 4.2</B>.
<H2><A NAME="what-is-postgres95">1.3. What is <B>POSTGRES95</B>?</A></H2>
<B>POSTGRES95</B> 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. <B>POSTGRES95</B> runs about 30-50%
faster on the Wisconsin Benchmark compared to v4.2.
Apart from bug fixes, these are the major enhancements:
<UL>
<LI>The query language <B>POSTQUEL</B> has been replaced with
<B>SQL</B> (implemented in the server). We do not support
subqueries (which can be imitated with user defined
<B>SQL</B> functions) at the moment. Aggregates have been
re-implemented. We also added support for <B>GROUP BY</B>.
The <B>libpq</B> interface is still available for <B>C</B>
programs.
<LI>In addition to the monitor program, we provide a new
program (<B>psql</B>) which supports <B>GNU</B> <B>readline</B>.
<LI>We added a new front-end library, <B>libpgtcl</B>, that
supports <B>Tcl</B>-based clients. A sample shell,
pgtclsh, provides new Tcl commands to interface <B>tcl</B>
programs with the <B>POSTGRES95</B> backend.
<LI>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.)
<LI>The instance-level rule system has been removed.
<LI>Rules are still available as rewrite rules.
<LI>A short tutorial introducing regular <B>SQL</B> features as
well as those of ours is distributed with the source
code.
<LI><B>GNU</B> make (instead of <B>BSD</B> make) is used for the
build. Also, <B>POSTGRES95</B> can be compiled with an
unpatched <B>gcc</B> (data alignment of doubles has been
fixed).
</UL>
<p>
<H2><A NAME="about-this-release">1.4. About This Release</A></H2>
<B>POSTGRES95</B> is available free of charge. This manual
describes version 1.0 of <B>POSTGRES95</B>. The authors have
compiled and tested <B>POSTGRES95</B> on the following
platforms:
<p>
<center>
<table border=4>
<tr>
<th>Architecture</th>
<th>Processor</th>
<th>Operating System</th>
</tr>
<tr>
<td>DECstation 3000</td>
<td>Alpha AXP</td>
<td>OSF/1 2.1, 3.0, 3.2</td>
</tr>
<tr>
<td>DECstation 5000</td>
<td>MIPS</td>
<td>ULTRIX 4.4</td>
</tr>
<tr>
<td>Sun4</td>
<td>SPARC</td>
<td>SunOS 4.1.3, 4.1.3_U1; Solaris 2.4</td>
</tr>
<tr>
<td>H-P 9000/700 and 800</td>
<td>PA-RISC</td>
<td>HP-UX 9.00, 9.01, 9.03</td>
</tr>
<tr>
<td>Intel</td>
<td>X86</td>
<td>Linux 1.2.8, ELF</td>
</table>
</center>
<p>
<H2><A NAME="outline-of-this-manual">1.5. Outline of This Manual</A></H2>
From now on, We will use POSTGRES to mean <B>POSTGRES95</B>.
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.
<HR>
<B>UNIX</B> 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.<p>
We assume proficiency with UNIX and C programming.
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