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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>2. A Brief History of PostgreSQL</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="intro-whatis.html" title="1. What is PostgreSQL?" /><link rel="next" href="notation.html" title="3. Conventions" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">2. A Brief History of <span xmlns="http://www.w3.org/1999/xhtml" class="productname">PostgreSQL</span></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="intro-whatis.html" title="1. What is PostgreSQL?">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="preface.html" title="Preface">Up</a></td><th width="60%" align="center">Preface</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="notation.html" title="3. Conventions">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="HISTORY"><div class="titlepage"><div><div><h2 class="title" style="clear: both">2. A Brief History of <span class="productname">PostgreSQL</span></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="history.html#HISTORY-BERKELEY">2.1. The Berkeley <span class="productname">POSTGRES</span> Project</a></span></dt><dt><span class="sect2"><a href="history.html#HISTORY-POSTGRES95">2.2. <span class="productname">Postgres95</span></a></span></dt><dt><span class="sect2"><a href="history.html#id-1.3.5.6">2.3. <span class="productname">PostgreSQL</span></a></span></dt></dl></div><a id="id-1.3.5.2" class="indexterm"></a><p>
The object-relational database management system now known as
<span class="productname">PostgreSQL</span> is derived from the
<span class="productname">POSTGRES</span> package written at the
University of California at Berkeley. With over two decades of
development behind it, <span class="productname">PostgreSQL</span> is now
the most advanced open-source database available anywhere.
</p><div class="sect2" id="HISTORY-BERKELEY"><div class="titlepage"><div><div><h3 class="title">2.1. The Berkeley <span class="productname">POSTGRES</span> Project</h3></div></div></div><a id="id-1.3.5.4.2" class="indexterm"></a><p>
The <span class="productname">POSTGRES</span> project, led by Professor
Michael Stonebraker, was sponsored by the Defense Advanced Research
Projects Agency (<acronym class="acronym">DARPA</acronym>), the Army Research
Office (<acronym class="acronym">ARO</acronym>), the National Science Foundation
(<acronym class="acronym">NSF</acronym>), and ESL, Inc. The implementation of
<span class="productname">POSTGRES</span> began in 1986. The initial
concepts for the system were presented in <a class="xref" href="biblio.html#STON86">[ston86]</a>,
and the definition of the initial data model appeared in <a class="xref" href="biblio.html#ROWE87">[rowe87]</a>. The design of the rule system at that time was
described in <a class="xref" href="biblio.html#STON87A">[ston87a]</a>. The rationale and
architecture of the storage manager were detailed in <a class="xref" href="biblio.html#STON87B">[ston87b]</a>.
</p><p>
<span class="productname">POSTGRES</span> has undergone several major
releases since then. The first <span class="quote">“<span class="quote">demoware</span>”</span> system
became operational in 1987 and was shown at the 1988
<acronym class="acronym">ACM-SIGMOD</acronym> Conference. Version 1, described in
<a class="xref" href="biblio.html#STON90A">[ston90a]</a>, was released to a few external users in
June 1989. In response to a critique of the first rule system
(<a class="xref" href="biblio.html#STON89">[ston89]</a>), the rule system was redesigned (<a class="xref" href="biblio.html#STON90B">[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 rule system. For the most part, subsequent releases
until <span class="productname">Postgres95</span> (see below) focused on
portability and reliability.
</p><p>
<span class="productname">POSTGRES</span> 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.
<span class="productname">POSTGRES</span> has also been used as an
educational tool at several universities. Finally, Illustra
Information Technologies (later merged into
<a class="ulink" href="https://www.ibm.com/analytics/informix" target="_top"><span class="productname">Informix</span></a>,
which is now owned by <a class="ulink" href="https://www.ibm.com/" target="_top">IBM</a>) picked up the code and
commercialized it. In late 1992,
<span class="productname">POSTGRES</span> became the primary data manager
for the
<a class="ulink" href="http://meteora.ucsd.edu/s2k/s2k_home.html" target="_top">
Sequoia 2000 scientific computing project</a>.
</p><p>
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
<span class="productname">POSTGRES</span> project officially ended with
Version 4.2.
</p></div><div class="sect2" id="HISTORY-POSTGRES95"><div class="titlepage"><div><div><h3 class="title">2.2. <span class="productname">Postgres95</span></h3></div></div></div><a id="id-1.3.5.5.2" class="indexterm"></a><p>
In 1994, Andrew Yu and Jolly Chen added an SQL language interpreter
to <span class="productname">POSTGRES</span>. Under a new name,
<span class="productname">Postgres95</span> was subsequently released to
the web to find its own way in the world as an open-source
descendant of the original <span class="productname">POSTGRES</span>
Berkeley code.
</p><p>
<span class="productname">Postgres95</span> code was completely ANSI C
and trimmed in size by 25%. Many internal changes improved
performance and
maintainability. <span class="productname">Postgres95</span> release
1.0.x ran about 30-50% faster on the Wisconsin Benchmark compared
to <span class="productname">POSTGRES</span>, Version 4.2. Apart from
bug fixes, the following were the major enhancements:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
The query language PostQUEL was replaced with
<acronym class="acronym">SQL</acronym> (implemented in the server). (Interface
library <a class="link" href="libpq.html" title="Chapter 34. libpq - C Library">libpq</a> was named after PostQUEL.)
Subqueries
were not supported until <span class="productname">PostgreSQL</span>
(see below), but they could be imitated in
<span class="productname">Postgres95</span> with user-defined
<acronym class="acronym">SQL</acronym> functions. Aggregate functions were
re-implemented. Support for the <code class="literal">GROUP BY</code>
query clause was also added.
</p></li><li class="listitem"><p>
A new program
(<span class="application">psql</span>) was provided for interactive
SQL queries, which used <acronym class="acronym">GNU</acronym>
<span class="application">Readline</span>. This largely superseded
the old <span class="application">monitor</span> program.
</p></li><li class="listitem"><p>
A new front-end library, <code class="filename">libpgtcl</code>,
supported <acronym class="acronym">Tcl</acronym>-based clients. A sample shell,
<code class="command">pgtclsh</code>, provided new Tcl commands to
interface <span class="application">Tcl</span> programs with the
<span class="productname">Postgres95</span> server.
</p></li><li class="listitem"><p>
The large-object interface was overhauled. The inversion large
objects were the only mechanism for storing large objects. (The
inversion file system was removed.)
</p></li><li class="listitem"><p>
The instance-level rule system was removed. Rules were still
available as rewrite rules.
</p></li><li class="listitem"><p>
A short tutorial introducing regular <acronym class="acronym">SQL</acronym>
features as well as those of
<span class="productname">Postgres95</span> was distributed with the
source code
</p></li><li class="listitem"><p>
<acronym class="acronym">GNU</acronym> make (instead of <acronym class="acronym">BSD</acronym>
make) was used for the build. Also,
<span class="productname">Postgres95</span> could be compiled with an
unpatched <span class="productname">GCC</span> (data alignment of
doubles was fixed).
</p></li></ul></div><p>
</p></div><div class="sect2" id="id-1.3.5.6"><div class="titlepage"><div><div><h3 class="title">2.3. <span class="productname">PostgreSQL</span></h3></div></div></div><p>
By 1996, it became clear that the name <span class="quote">“<span class="quote">Postgres95</span>”</span>
would not stand the test of time. We chose a new name,
<span class="productname">PostgreSQL</span>, to reflect the relationship
between the original <span class="productname">POSTGRES</span> and the
more recent versions with <acronym class="acronym">SQL</acronym> 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 <span class="productname">POSTGRES</span> project.
</p><p>
Many people continue to refer to
<span class="productname">PostgreSQL</span> as <span class="quote">“<span class="quote">Postgres</span>”</span>
(now rarely in all capital letters) because of tradition or because
it is easier to pronounce. This usage is widely accepted as a
nickname or alias.
</p><p>
The emphasis during development of
<span class="productname">Postgres95</span> was on identifying and
understanding existing problems in the server code. With
<span class="productname">PostgreSQL</span>, the emphasis has shifted to
augmenting features and capabilities, although work continues in
all areas.
</p><p>
Details about what has happened in <span class="productname">PostgreSQL</span> since
then can be found in <a class="xref" href="release.html" title="Appendix E. Release Notes">Appendix E</a>.
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