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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML
><HEAD
><TITLE
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><H1
><A
NAME="INTRO"
>Chapter 1. Introduction</A
></H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="intro.html#AEN34"
>What is <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
>?</A
></DT
><DT
><A
HREF="intro56.html"
>A Short History of <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
></A
></DT
><DT
><A
HREF="intro149.html"
>About This Release</A
></DT
><DT
><A
HREF="intro159.html"
>Resources</A
></DT
><DT
><A
HREF="intro228.html"
>Terminology</A
></DT
><DT
><A
HREF="intro259.html"
>Notation</A
></DT
><DT
><A
HREF="intro286.html"
>Y2K Statement</A
></DT
><DT
><A
HREF="intro317.html"
>Copyrights and Trademarks</A
></DT
></DL
></DIV
><P
> This document is the user manual for the
<A
HREF="http://postgresql.org/"
TARGET="_top"
><SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></A
>
database management system, originally developed at the University
of California at Berkeley.
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> is based on
<A
HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/postgres.html"
TARGET="_top"
> <SPAN
CLASS="PRODUCTNAME"
>Postgres release 4.2</SPAN
></A
>.
The <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
> project,
led by Professor Michael Stonebraker, was sponsored by the
Defense Advanced Research Projects Agency (<SPAN
CLASS="ACRONYM"
>DARPA</SPAN
>), the
Army Research Office (<SPAN
CLASS="ACRONYM"
>ARO</SPAN
>), the National Science
Foundation (<SPAN
CLASS="ACRONYM"
>NSF</SPAN
>), and ESL, Inc.</P
><H1
CLASS="SECT1"
><A
NAME="AEN34"
>What is <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
>?</A
></H1
><P
> 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.
<SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
> offers substantial additional
power by incorporating the following four additional
basic concepts in such a way that users can easily
extend the system:
<P
></P
><TABLE
BORDER="0"
><TR
><TD
>classes</TD
></TR
><TR
><TD
>inheritance</TD
></TR
><TR
><TD
>types</TD
></TR
><TR
><TD
>functions</TD
></TR
></TABLE
><P
></P
></P
><P
>Other features provide additional power and flexibility:
<P
></P
><TABLE
BORDER="0"
><TR
><TD
>constraints</TD
></TR
><TR
><TD
>triggers</TD
></TR
><TR
><TD
>rules</TD
></TR
><TR
><TD
>transaction integrity</TD
></TR
></TABLE
><P
></P
></P
><P
>These features put <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
> into the category of databases
referred to as <I
CLASS="FIRSTTERM"
>object-relational</I
>. Note that this is distinct
from those referred to as <I
CLASS="FIRSTTERM"
>object-oriented</I
>, which in general
are not as well suited to supporting the traditional relational database languages.
So, although <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
> has some object-oriented features,
it is firmly in the relational database world. In fact, some commercial databases
have recently incorporated features pioneered by <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
>. </P
><DIV
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><HR
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BORDER="0"
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>Home</A
></TD
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></TD
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><TR
><TD
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>Summary</TD
><TD
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>;</TD
><TD
WIDTH="33%"
ALIGN="right"
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>A Short History of <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
></TD
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>
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