<Sect1>
<Title>A Short History of <ProductName>Postgres</ProductName></Title>
<Sect2>
<Title>The Berkeley <ProductName>Postgres</ProductName> Project</Title>
<Para>
Implementation of the <ProductName>Postgres</ProductName>
<Acronym>DBMS</Acronym> began in 1986. The
initial concepts for the system were presented in
<XRef LinkEnd="STON86" endterm="STON86-full">
and the definition of the initial data model
appeared in
<XRef LinkEnd="ROWE87" endterm="ROWE87-full">.
The design of the rule system at
that time was described in
<XRef LinkEnd="STON87a" endterm="STON87a-full">.
The rationale
and architecture of the storage manager were detailed in
<XRef LinkEnd="STON87b" endterm="STON87b-full">.
</Para>
<Para>
<ProductName>Postgres</ProductName> has undergone several major releases since
then. The first "demoware" system became operational
in 1987 and was shown at the 1988 <Acronym>ACM-SIGMOD</Acronym>
Conference. We released Version 1, described in
<XRef LinkEnd="STON90a" endterm="STON90a-full">,
to a few external users in June 1989. In response to a
critique of the first rule system
(<XRef LinkEnd="STON89" endterm="STON89-full">),
the rule
system was redesigned
(<XRef LinkEnd="STON90b" endterm="STON90b-full">)
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.
</Para>
<Para>
<ProductName>Postgres</ProductName> 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.
<ProductName>Postgres</ProductName> has also been
used as an educational tool at several universities.
Finally,
<Ulink url="http://www.illustra.com/">Illustra Information Technologies</Ulink>
(since merged into
<Ulink url="http://www.informix.com/">Informix</Ulink>)
picked up
the code and commercialized it.
<ProductName>Postgres</ProductName> became the primary data manager
for the
<Ulink url="http://www.sdsc.edu/0/Parts_Collabs/S2K/s2k_home.html">Sequoia 2000</Ulink>
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.
</Para>
</Sect2>
<Sect2>
<Title><ProductName>Postgres95</ProductName></Title>
<Para>
In 1994,
<ULink url="mailto:ayu@informix.com">Andrew Yu</ULink>
and
<ULink url="http://http.cs.berkeley.edu/~jolly/">Jolly Chen</ULink>
added a SQL language interpreter to <ProductName>Postgres</ProductName>,
and the code was subsequently released to
the Web to find its own way in the world.
<ProductName>Postgres95</ProductName> was a public-domain, open source descendant
of this original Berkeley code.
</Para>
<Para>
<ProductName>Postgres95</ProductName> is a derivative of the last official release
of <ProductName>Postgres</ProductName> (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.
<ProductName>Postgres95</ProductName> 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:
<ItemizedList>
<ListItem>
<Para>
The query language <ProductName>Postquel</ProductName> has been replaced with
<Acronym>SQL</Acronym> (implemented in the server). We do not yet support
subqueries (which can be imitated with user defined
<Acronym>SQL</Acronym> functions). Aggregates have been
re-implemented. We also added support for ``GROUP BY''.
The <FileName>libpq</FileName> interface is still available for <Acronym>C</Acronym>
programs.
</Para>
</ListItem>
<ListItem>
<Para>
In addition to the monitor program, we provide a new
program (<Application>psql</Application>) which supports <Acronym>GNU</Acronym> <FileName>readline</FileName>.
</Para>
</ListItem>
<ListItem>
<Para>
We added a new front-end library, <FileName>libpgtcl</FileName>, that
supports <Acronym>Tcl</Acronym>-based clients. A sample shell,
pgtclsh, provides new Tcl commands to interface <Application>tcl</Application>
programs with the <ProductName>Postgres95</ProductName> backend.
</Para>
</ListItem>
<ListItem>
<Para>
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.)
</Para>
</ListItem>
<ListItem>
<Para>
The instance-level rule system has been removed.
Rules are still available as rewrite rules.
</Para>
</ListItem>
<ListItem>
<Para>
A short tutorial introducing regular <Acronym>SQL</Acronym> features as
well as those of ours is distributed with the source
code.
</Para>
</ListItem>
<ListItem>
<Para>
<Acronym>GNU</Acronym> make (instead of <Acronym>BSD</Acronym> make) is used for the
build. Also, <ProductName>Postgres95</ProductName> can be compiled with an
unpatched <ProductName>gcc</ProductName> (data alignment of doubles has been
fixed).
</Para>
</ListItem>
</ItemizedList>
</Para>
</Sect2>
<Sect2>
<Title><ProductName>PostgreSQL</ProductName></Title>
<Para>
By 1996, it became clear that the name <Quote>Postgres95</Quote> would not stand
the test of time. A new name, <ProductName>PostgreSQL</ProductName>,
was chosen to reflect the
relationship between original <ProductName>Postgres</ProductName>
and the more recent
versions with <Acronym>SQL</Acronym> 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 <ProductName>Postgres</ProductName> Project.
<Para>
The emphasis on development for the v1.0.x releases of
<ProductName>Postgres95</ProductName>
was on stabilizing the backend code.
With the v6.x series of <ProductName>PostgreSQL</ProductName>,
the emphasis has shifted from
identifying and understanding existing problems in the backend
to augmenting features and capabilities, although
work continues in all areas.
<Para>
Major enhancements include:
<ItemizedList>
<ListItem>
<Para>
Important backend features, including subselects, defaults,
constraints, and triggers, have been implemented.
</Para>
</ListItem>
<ListItem>
<Para>
Additional <Acronym>SQL92</Acronym>-compliant language features have been added,
including primary keys, quoted identifiers, literal string type coersion,
type casting, and binary and hexadecimal integer input.
</Para>
</ListItem>
<ListItem>
<Para>
Built-in types have been improved, including new wide-range date/time types
and additional geometric type support.
</Para>
</ListItem>
<ListItem>
<Para>
Overall backend code speed has been increased by approximately 20-40%,
and backend startup time has decreased 80% since v6.0 was released.
</Para>
</ListItem>
</ItemizedList>
</Para>
</Sect2>
</sect1>