<para>

This book is the official documentation of

<productname>PostgreSQL</productname>. It has been written by the

<productname>PostgreSQL</productname> developers and other

<productname>&productname;</productname>. It has been written by the

<productname>&productname;</productname> developers and other

volunteers in parallel to the development of the

<productname>PostgreSQL</productname> software. It describes all

<productname>&productname;</productname> software. It describes all

the functionality that the current version of

<productname>PostgreSQL</productname> officially supports.

<productname>&productname;</productname> officially supports.

</para>

<para>

To make the large amount of information about

<productname>PostgreSQL</productname> manageable, this book has been

<productname>&productname;</productname> manageable, this book has been

organized in several parts. Each part is targeted at a different

class of users, or at users in different stages of their

<productname>PostgreSQL</productname> experience:

<productname>&productname;</productname> experience:

<itemizedlist>

<listitem>

<xref linkend="sql"> documents the <acronym>SQL</acronym> query

language environment, including data types and functions, as well

as user-level performance tuning. Every

<productname>PostgreSQL</> user should read this.

<productname>&productname;</> user should read this.

</para>

</listitem>

<listitem>

<para>

<xref linkend="admin"> describes the installation and

administration of the server. Everyone who runs a

<productname>PostgreSQL</productname> server, be it for private

<productname>&productname;</productname> server, be it for private

use or for others, should read this part.

</para>

</listitem>

<listitem>

<para>

<xref linkend="client-interfaces"> describes the programming

interfaces for <productname>PostgreSQL</productname> client

interfaces for <productname>&productname;</productname> client

programs.

</para>

</listitem>

<listitem>

<para>

<xref linkend="internals"> contains assorted information that might be of

use to <productname>PostgreSQL</> developers.

use to <productname>&productname;</> developers.

</para>

</listitem>

</itemizedlist>

</para>

<sect1 id="intro-whatis">

<title> What is <productname>PostgreSQL</productname>?</title>

<title> What is <productname>&productname;</productname>?</title>

<para>

<productname>PostgreSQL</productname> is an object-relational

database management system (<acronym>ORDBMS</acronym>) based on

<productname>&productname;</productname> is an object-relational

database management system (<acronym>ORDBMS</acronym>), developed by Postgres Professional on the base of<ulink

url="http://postgresql.org"><productname>PostgreSQL</productname></ulink>, which is in turn based on

<ulink url="http://db.cs.berkeley.edu/postgres.html">

<productname>POSTGRES, Version 4.2</productname></ulink>,

developed at the University of California at Berkeley Computer Science

</listitem>

</itemizedlist>

Also, <productname>PostgreSQL</productname> can be extended by the

Also, <productname>&productname;</productname>, as well as <productname>PostgreSQL</productname>, can be extended by the

user in many ways, for example by adding new

<itemizedlist spacing="compact">

<para>

And because of the liberal license,

<productname>PostgreSQL</productname> can be used, modified, and

<productname>&productname;</productname> and <productname>PostgreSQL</productname> can be used, modified, and

distributed by anyone free of charge for any purpose, be it

private, commercial, or academic.

</para>

</sect1>

<sect1 id="intro-pgpro-vs-pg">

<title> Difference between <productname>&productname;</productname> and PostgreSQL</title>

<para>

<productname>&productname;</productname> is the most actual PostgreSQL version with some additional patches applied and extensions added.

Mostly, these are patches already accepted by the PostgreSQL community and committed into PostgreSQL.

Also there some patches and extensions developed by Postgres Professional.

Users of <productname>&productname;</productname> thus have early access to some important features and fixes.

</para>

<para>Currently the difference between <productname>&productname;</productname> and PostgreSQL is the following:

<itemizedlist spacing="compact">

<listitem>

<simpara>Performance improvement on multicore systems (buffer manager and locks optimization).</simpara>

</listitem>

<listitem>

<simpara>Full text search improvements: phrase search, hunspell morphology,

some dictionaries are bundled with distribution and can be enabled by a single SQL statement,

<application>shared_ispell</application> allowing to store dictionaries in shared memory.</simpara>

</listitem>

<listitem>

<simpara>Covering indexes.</simpara>

</listitem>

<listitem>

<simpara><application>libicu</application> support on all platforms, providing platform-independent sort for various locales.</simpara>

</listitem>

<listitem>

<simpara><application>pg_trgm</application> module supporting fuzzy string comparison and substring search.</simpara>

</listitem>

<listitem>

<simpara>Improved <application>pageinspect</application> module provides access to internal data storage structure.</simpara>

</listitem>

<listitem>

<simpara><application>sr_plan</application> module allows to save and restore query plans.</simpara>

</listitem>

<listitem>

<simpara><application>dump_stat</application> module allowing to save and restore database statistics when dumping/restoring the database. </simpara>

</listitem>

<listitem>

<simpara><application>jsquery</application> module provides a specific language for effective index-supported querying of JSONB data.</simpara>

</listitem>

</itemizedlist>

</para>

<para>

<productname>&productname;</productname> releases are following the PostgreSQL releases, though sometimes occur more frequently.

The <productname>&productname;</productname> versioning scheme is based on the PostgreSQL one and has an additional decimal place.

</para>

</sect1>

&history;