<Chapter>
<TITLE>Introduction</TITLE>

<Para>
     This document is the programmer's  manual  for  the  
     <Ulink url="http://postgresql.org/"><ProductName>PostgreSQL</ProductName></Ulink>
     database  management system, originally developed at the University
     of California at  Berkeley.   <ProductName>PostgreSQL</ProductName>  is  based  on
     <Ulink url="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/postgres.html">
     <ProductName>Postgres release 4.2</ProductName></Ulink>. 
The <ProductName>Postgres</ProductName> project, 
     led by Professor Michael Stonebraker, has been sponsored  by  the
     Defense  Advanced Research Projects Agency (<Acronym>DARPA</Acronym>), the
     Army Research Office (<Acronym>ARO</Acronym>), the National Science  
     Foundation (<Acronym>NSF</Acronym>), and ESL, Inc.
</Para>

<Para>
     The first part of this manual 
     explains  the
     <ProductName>Postgres</ProductName>  approach  to  extensibility  and describe how
     users can extend <ProductName>Postgres</ProductName> by adding user-defined types,
     operators, aggregates, and both query language and programming language functions.
     After an extremely  brief
     overview  of  the <ProductName>Postgres</ProductName> rule system, we discuss
     the trigger and SPI interfaces.
     The manual concludes with a detailed description of the programming interfaces and
     support libraries for various languages.
</Para>

<Para>
     We assume proficiency with UNIX and C programming.
</Para>

<Sect1>
<Title>Copyrights and Trademarks</Title>

<Para>
<ProductName>PostgreSQL</ProductName> is copyright (C) 1996-8 by the PostgreSQL Global Development Group,
and is distributed under the terms of the Berkeley license.

<Para>
<ProductName>Postgres95</ProductName> 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.
</Para>
<Para>
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.
</Para>
<Para>
The University of California specifically disclaims any
warranties, including, but not limited to, the implied warranties
of merchantability and fitness for a particular purpose.
The software provided hereunder is on an "as-is" basis, and
the University of California has no obligations to provide
maintainance, support, updates, enhancements, or modifications.
</Para>

<Para>
<Acronym>UNIX</Acronym> 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.
</Para>

</Chapter>
