-<!-- $PostgreSQL: pgsql/doc/src/sgml/release-9.0.sgml,v 2.32 2010/06/16 14:50:34 adunstan Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/release-9.0.sgml,v 2.33 2010/06/16 18:31:39 momjian Exp $ -->
<sect1 id="release-9-0">
<title>Release 9.0</title>
Add support for compiling on <link
linkend="install-win32-full">64-bit
<productname>Windows</></link> and running in 64-bit
- mode
+ mode.
</para>
</listitem>
<para>CURRENT AS OF 2010-06-03</para>
<para>
- A dump/restore using <application>pg_dump</application> is
- required for those wishing to migrate data from any previous
+ A dump/restore using <application>pg_dump</application>
+ or use of <application>pg_upgrade</application> is required
+ for those wishing to migrate data from any previous
release.
</para>
<para>
- Observe the following incompatibilities:
+ Version 9.0 contains a number of changes which selectively break backwards compatibility
+ in order to support new features and code quality improvements. Particularly, users
+ who make extensive use of PL/pgSQL and/or PITR and Warm Standby should test their
+ solutions for breakage. Observe the following incompatibilities:
</para>
<sect3>
linkend="guc-geqo-seed">geqo_seed</link> to randomize
the starting value of the random plan generator.
</para>
+
+ <para>
+ This gives GEQO query response times and resource usage
+ repeatability and predictability.
+ </para>
+
</listitem>
<listitem>
name</link>, which is displayed in
<structname>pg_stat_activity</> (Dave Page)
</para>
+
+ <para>
+ This allows DBAs to characterize database traffic
+ and troubleshoot problems by source application.
+ </para>
</listitem>
<listitem>
in the new <structname>pg_db_role_setting</> system table. A new
<application>psql</> <literal>\drds</> command shows these settings.
Backwards-compatible system views do not show this information.
+ The primary use of this feature is setting schema
+ <link linkend="guc-search-path"><varname>search_path</varname></link>.
</para>
+
+
</listitem>
<listitem>
Log changed parameter values when <filename>postgresql.conf</> is
reloaded (Peter Eisentraut)
</para>
+
+ <para>
+ This lets DBAs and security staff to audit when database settings
+ were changed.
+ </para>
+
</listitem>
<listitem>
(Boszormenyi Zoltan)
</para>
+ <para>
+ For drivers which support this feature, this saves an entire
+ round-trip to the client, allowing result counts and pagination
+ to be calculated without a second <command>COUNT</command> query.
+ </para>
+
<para>
<application>psql</> does not display these counts.
</para>
<para>
Such operations either complete fully or are rolled back, so
<acronym>WAL</> archiving can be skipped, unless running in continuous
- archiving mode.
+ archiving mode. This reduces I/O overhead and improves performance.
</para>
</listitem>
<function>PQescapeByteaConn()</> now uses the hex format
for <productname>PostgreSQL</> 9.0 servers.
</para>
+
+ <para>
+ The new hex format will be directly compatible with more applications
+ which use binary data, allowing them to store and retrieve
+ it without conversion.
+ </para>
+
</listitem>
<listitem>
<para>
For example, this is now supported, <literal>array_agg(a ORDER BY
b)</>. This is useful for aggregates where the order of values is
- significant.
+ significant, and eliminates the need to have a subquery for
+ the ordering.
</para>
</listitem>