<simpara>2011-??-??</simpara>

</note>

<para>CURRENT AS OF 2011-07-07</para>

<para>CURRENT AS OF 2011-08-17</para>

<sect2>

<title>Overview</title>

<para>

This release shows <productname>PostgreSQL</> moving beyond the

traditional relational feature set with new, ground-breaking

traditional relational-database feature set with new, ground-breaking

functionality that is unique to <productname>PostgreSQL</>.

Additionally, this release improves streaming replication by adding

a synchronous option and monitoring improvements. Major enhancements

include:

The streaming replication feature introduced in release 9.0 is

significantly enhanced by adding a synchronous-replication option,

streaming backups, and monitoring improvements.

Major enhancements include:

</para>

<itemizedlist>

<!-- This list duplicates items below, but without authors or details-->

<listitem>

<para>

Support unlogged tables using the <link

linkend="SQL-CREATETABLE-description"><literal>UNLOGGED</></link>

option in <link linkend="SQL-CREATETABLE"><command>CREATE

TABLE</></link>

</para>

</listitem>

<listitem>

<para>

Allow <link linkend="synchronous-replication">synchronous

<listitem>

<para>

Adda<link linkend="SQL-SECURITY-LABEL"><command>SECURITY

Add <link linkend="extend-extensions">extensions</link> which

</para>

</listitem>

<listitem>

<para>

Add a true <link

linkend="xact-serializable">serializable</link> isolation

level

linkend="xact-serializable">serializable isolation level</link>

</para>

</listitem>

<listitem>

<para>

Support unlogged tables using the <literal>UNLOGGED</>

option in <link linkend="SQL-CREATETABLE"><command>CREATE

TABLE</></link>

</para>

</listitem>

<listitem>

<para>

Add <link linkend="extend-extensions">extensions</link> which

simplify packaging of additions to <productname>PostgreSQL</>

Add a <link linkend="SQL-SECURITY-LABEL"><command>SECURITY

LABEL</></link> command and support for

<link linkend="sepgsql"><acronym>SELinux</> permissions control</link>

</para>

</listitem>

strings are the proper way to embed backslash escapes in strings and are

unaffected by this change.

</para>

<warning>

<para>

This change can break applications that are not expecting it and

do their own string escaping according to the old rules. The

consequences could be as severe as introducing SQL-injection security

holes. Be sure to test applications that are exposed to untrusted

input, to ensure that they correctly handle single quotes and

backslashes in text strings.

</para>

</warning>

</listitem>

</itemizedlist>

<listitem>

<para>

Treat <application>ECPG</> cursor names as case-insensitive (Zoltan Boszormenyi)

Treat <application>ECPG</> cursor names as case-insensitive

(Zoltan Boszormenyi)

</para>

</listitem>

<sect2>

<title>Changes</title>

<para>

Version 9.1 has ...

</para>

<para>

Below you will find a detailed account of the changes between

<productname>PostgreSQL</productname> 9.1 and the previous major

release.

</para>

<sect3>

<title>Server</title>

<listitem>

<para>

Support unlogged tables using the <link

linkend="SQL-CREATETABLE-description"><literal>UNLOGGED</></link>

Support unlogged tables using the <literal>UNLOGGED</>

option in <link linkend="SQL-CREATETABLE"><command>CREATE

TABLE</></link> (Robert Haas)

</para>

<listitem>

<para>

Merge duplicate fsync requests on busy systems (Robert Haas,

Greg Smith)

Merge duplicate fsync requests (Robert Haas, Greg Smith)

</para>

<para>

This greatly improves performance under heavy write loads.

</para>

</listitem>

</para>

<para>

The old term is still accepted for backward compatibility.

The old term is still accepted for backward compatibility, but since

the two methods are fundamentally different, it seemed better to adopt

different names for them.

</para>

</listitem>

</para>

</listitem>

<listitem>

<para>

Reduce the default maximum line length for <application>syslog</>

logging to 900 bytes plus prefixes (Noah Misch)

</para>

<para>

This avoids truncation of long log lines on syslog implementations

that have a 1KB length limit, rather than the more common 2KB.

</para>

</listitem>

</itemizedlist>

</sect4>

</para>

<para>

This allows external cluster management software totakecontrol

ofwhetherservers restart or not.

This allows external cluster management software to control

whetherthe database server restarts or not.

</para>

</listitem>

<listitem>

<para>

Add a true <link

linkend="xact-serializable">serializable</link> isolation

level(Kevin Grittner, Dan Ports)

linkend="xact-serializable">serializable isolation level</link>

(Kevin Grittner, Dan Ports)

</para>

<para>

<listitem>

<para>

Prevent <link linkend="autovacuum">autovacuum</link> from

waiting if it cannot acquire a lock (Robert Haas)

waiting if it cannot acquire atablelock (Robert Haas)

</para>

<para>

It will try to vacuum later.

It will try to vacuumthat tablelater.

</para>

</listitem>

<para>

This allows <acronym>GiST</> indexes to quickly return the

<replaceable>N</> closest values in a query with <literal>LIMIT</>.

For example

<programlisting><![CDATA[

SELECT * FROM places ORDER BY location <-> point '(101,456)' LIMIT 10;

]]>

</programlisting>

finds the ten places closest to a given target point.

</para>

</listitem>

<listitem>

<para>

Add <link linkend="plpgsql-foreach-array"><command>FOREACH IN

ARRAY</></link> to<link linkend="plpgsql">PL/pgSQL</link>

ARRAY</></link> to PL/pgSQL

(Pavel Stehule)

</para>

<listitem>

<para>

AddPL/Pythonexplicit subtransactions (Jan Urbanski)

Add explicit subtransactions to PL/Python (Jan Urbanski)

</para>

</listitem>

<listitem>

<para>

Add <option>S</> (<quote>system</>) option to <application>psql</>'s

Addthe<option>S</> (<quote>system</>) option to <application>psql</>'s

<literal>\dn</> (list schemas) command (Tom Lane)

</para>

<listitem>

<para>

Add a libpq connection option <literal>client_encoding</>

Add a libpq connection option <link

linkend="libpq-connect-client-encoding"><literal>client_encoding</></link>

which behaves like the <envar>PGCLIENTENCODING</> environment

variable (Heikki Linnakangas)

</para>

<listitem>

<para>

Allow libpq database clients to

check the user name of the server process using <link

Allow libpq-using clients to

check the user name of the server process

when connecting via Unix-domain sockets, with the new <link

linkend="libpq-connect-requirepeer"><literal>requirepeer</></link>

(Peter Eisentraut)

</para>

<listitem>

<para>

Allow ECPG to accept dynamic cursor names even in

<literal>WHERE CURRENT OF</literal> clauses

Allow ECPG to accept dynamic cursor names even in

<literal>WHERE CURRENT OF</literal> clauses

(Zoltan Boszormenyi)

</para>

</listitem>

<listitem>

<para>

Make <application>ecpglib</> write <type>double</> values with a

precision of 15 digits, not 14 as formerly (Akira Kurosawa)

</para>

</listitem>

<listitem>

<para>

Add latches to the source code towait for events (Heikki

Linnakangas)

Add latches to the source code tosupport waiting for events (Heikki

Linnakangas)

</para>

</listitem>

<listitem>

<para>

Add nearest-neighbor support to <link

Add nearest-neighborsearchsupport to <link

linkend="pgtrgm"><filename>contrib/pg_trgm</></link> and <link

linkend="btree-gist"><filename>contrib/btree_gist</></link>

(Teodor Sigaev)

<listitem>

<para>

Add <link linkend="sepgsql"><filename>contrib/sepgsql</></link>

to interface permission checks with <acronym>SE</>-Linux (KaiGai Kohei)

to interface permission checks with <acronym>SELinux</> (KaiGai Kohei)

</para>

<para>

<listitem>

<para>

Add <link linkend="dummy-seclabel">dummy_seclabel</link>

Add <link linkend="dummy-seclabel"><filename>dummy_seclabel</></link>

contrib module (KaiGai Kohei)

</para>

<listitem>

<para>

Extensive <link linkend="ecpg"><application>ECPG</> documentation</link>

improvements (Satoshi Nagayasu)

Extensive <link linkend="ecpg"><application>ECPG</></link>

documentationimprovements (Satoshi Nagayasu)

</para>

</listitem>

<listitem>

<para>

Mergedocs for <command>CREATE CONSTRAINT TRIGGER</> and <link

Mergedocumentation for <command>CREATE CONSTRAINT TRIGGER</> and <link

linkend="SQL-CREATETRIGGER"><command>CREATE TRIGGER</></link>

(Alvaro Herrera)

</para>