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><H1
CLASS="SECT1"
><A
NAME="HISTORY"
>2. A Short History of <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></A
></H1
><P
> The object-relational database management system now known as
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> (and briefly called
<SPAN
CLASS="PRODUCTNAME"
>Postgres95</SPAN
>) is derived from the
<SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
> package written at the University of
California at Berkeley. With over a decade of
development behind it, <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
is the most advanced open-source database available anywhere,
offering multiversion concurrency control, supporting almost
all SQL constructs (including subselects, transactions, and
user-defined types and functions), and having a wide range of
language bindings available (including C, C++, Java, Perl, Tcl, and Python).
</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN721"
>2.1. The Berkeley <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
> Project</A
></H2
><P
> Implementation of the <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
>
<SPAN
CLASS="ACRONYM"
>DBMS</SPAN
> began in 1986. The
initial concepts for the system were presented in
<A
HREF="biblio.html#STON86"
><I
><A
HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M85-95.pdf"
TARGET="_top"
>The design of <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
></A
></I
></A
>
and the definition of the initial data model
appeared in
<A
HREF="biblio.html#ROWE87"
><I
><A
HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M87-13.pdf"
TARGET="_top"
>The <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
> data model</A
></I
></A
>.
The design of the rule system at
that time was described in
<A
HREF="biblio.html#STON87A"
><I
>The design of the <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
> rules system</I
></A
>.
The rationale
and architecture of the storage manager were detailed in
<A
HREF="biblio.html#STON87B"
><I
><A
HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M87-06.pdf"
TARGET="_top"
>The design of the <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
> storage system</A
></I
></A
>.
</P
><P
> <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
> has undergone several major releases since
then. The first <SPAN
CLASS="QUOTE"
>"demoware"</SPAN
> system became operational
in 1987 and was shown at the 1988 <SPAN
CLASS="ACRONYM"
>ACM-SIGMOD</SPAN
>
Conference. Version 1, described in
<A
HREF="biblio.html#STON90A"
><I
><A
HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M90-34.pdf"
TARGET="_top"
>The implementation of <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
></A
></I
></A
>, was released
to a few external users in June 1989. In response to a
critique of the first rule system
(<A
HREF="biblio.html#STON89"
><I
><A
HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M89-82.pdf"
TARGET="_top"
>A commentary on the <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
> rules system</A
></I
></A
>),
the rule
system was redesigned
(<A
HREF="biblio.html#STON90B"
><I
><A
HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/papers/ERL-M90-36.pdf"
TARGET="_top"
>On Rules, Procedures, Caching and Views in Database Systems</A
></I
></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, 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
HREF="http://www.informix.com/"
TARGET="_top"
><SPAN
CLASS="PRODUCTNAME"
>Informix</SPAN
></A
>,
which is now owned by <A
HREF="http://www.ibm.com/"
TARGET="_top"
>IBM</A
>.)
picked up
the code and commercialized it.
<SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
> became the primary data manager
for the
<A
HREF="http://meteora.ucsd.edu/s2k/s2k_home.html"
TARGET="_top"
>Sequoia 2000</A
>
scientific computing project in late 1992.
</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"
><H2
CLASS="SECT2"
><A
NAME="AEN749"
>2.2. <SPAN
CLASS="PRODUCTNAME"
>Postgres95</SPAN
></A
></H2
><P
> In 1994, Andrew Yu and Jolly Chen
added a SQL language interpreter to <SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
>.
<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
></P
></P><UL
><LI
><P
> The query language PostQUEL was replaced with
<SPAN
CLASS="ACRONYM"
>SQL</SPAN
> (implemented in the server).
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
<SPAN
CLASS="ACRONYM"
>SQL</SPAN
> functions. Aggregates were
re-implemented. Support for the GROUP BY query clause was also added.
The <TT
CLASS="FILENAME"
>libpq</TT
> interface remained
available for <SPAN
CLASS="ACRONYM"
>C</SPAN
>
programs.
</P
></LI
><LI
><P
> In addition to the monitor program, a new program
(<SPAN
CLASS="APPLICATION"
>psql</SPAN
>) was provided for interactive SQL queries
using <SPAN
CLASS="ACRONYM"
>GNU</SPAN
> <SPAN
CLASS="APPLICATION"
>Readline</SPAN
>.
</P
></LI
><LI
><P
> A new front-end library, <TT
CLASS="FILENAME"
>libpgtcl</TT
>,
supported <SPAN
CLASS="ACRONYM"
>Tcl</SPAN
>-based clients. A sample shell,
<TT
CLASS="COMMAND"
>pgtclsh</TT
>, provided new Tcl commands to interface
<SPAN
CLASS="APPLICATION"
>Tcl</SPAN
>
programs with the <SPAN
CLASS="PRODUCTNAME"
>Postgres95</SPAN
> backend.
</P
></LI
><LI
><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
><P
> The instance-level rule system was removed.
Rules were still available as rewrite rules.
</P
></LI
><LI
><P
> A short tutorial introducing regular <SPAN
CLASS="ACRONYM"
>SQL</SPAN
> features as
well as those of <SPAN
CLASS="PRODUCTNAME"
>Postgres95</SPAN
> was
distributed with the source code
</P
></LI
><LI
><P
> <SPAN
CLASS="ACRONYM"
>GNU</SPAN
> make (instead of <SPAN
CLASS="ACRONYM"
>BSD</SPAN
> 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
><P>
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN795"
>2.3. <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></A
></H2
><P
> By 1996, it became clear that the name <SPAN
CLASS="QUOTE"
>"Postgres95"</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 <SPAN
CLASS="ACRONYM"
>SQL</SPAN
> 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
> The emphasis during development of <SPAN
CLASS="PRODUCTNAME"
>Postgres95</SPAN
>
was on identifying and understanding existing problems in the backend code.
With <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>,
the emphasis has shifted to augmenting features and capabilities, although
work continues in all areas.
</P
><P
> Major enhancements in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> include:
</P
><P
></P
><UL
><LI
><P
> Table-level locking has been replaced by multiversion concurrency control,
which allows readers to continue reading consistent data during writer activity
and enables hot backups from <SPAN
CLASS="APPLICATION"
>pg_dump</SPAN
> while the database stays available for
queries.
</P
></LI
><LI
><P
> Important backend features, including subselects, defaults,
constraints, and triggers, have been implemented.
</P
></LI
><LI
><P
> Additional <SPAN
CLASS="ACRONYM"
>SQL92</SPAN
>-compliant language features have been added,
including primary keys, quoted identifiers, literal string type coercion,
type casting, and binary and hexadecimal integer input.
</P
></LI
><LI
><P
> Built-in types have been improved, including new wide-range date/time types
and additional geometric type support.
</P
></LI
><LI
><P
> Overall backend code speed has been increased by approximately 20-40%,
and backend start-up time has decreased by 80% since version 6.0 was released.
</P
></LI
></UL
></DIV
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