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<sect1 id="release-9-1-23">

<title>Release 9.1.23</title>

<note>

<title>Release Date</title>

<simpara>2016-08-11</simpara>

</note>

<para>

This release contains a variety of fixes from 9.1.22.

For information about new features in the 9.1 major release, see

<xref linkend="release-9-1">.

</para>

<para>

The <productname>PostgreSQL</> community will stop releasing updates

for the 9.1.X release series in September 2016.

Users are encouraged to update to a newer release branch soon.

</para>

<sect2>

<title>Migration to Version 9.1.23</title>

<para>

A dump/restore is not required for those running 9.1.X.

</para>

<para>

However, if you are upgrading from a version earlier than 9.1.16,

see <xref linkend="release-9-1-16">.

</para>

</sect2>

<sect2>

<title>Changes</title>

<itemizedlist>

<listitem>

<para>

Fix corner-case misbehaviors for <literal>IS NULL</>/<literal>IS NOT

NULL</> applied to nested composite values (Andrew Gierth, Tom Lane)

</para>

<para>

The SQL standard specifies that <literal>IS NULL</> should return

TRUE for a row of all null values (thus <literal>ROW(NULL,NULL) IS

NULL</> yields TRUE), but this is not meant to apply recursively

(thus <literal>ROW(NULL, ROW(NULL,NULL)) IS NULL</> yields FALSE).

The core executor got this right, but certain planner optimizations

treated the test as recursive (thus producing TRUE in both cases),

and <filename>contrib/postgres_fdw</> could produce remote queries

that misbehaved similarly.

</para>

</listitem>

<listitem>

<para>

Make the <type>inet</> and <type>cidr</> data types properly reject

IPv6 addresses with too many colon-separated fields (Tom Lane)

</para>

</listitem>

<listitem>

<para>

Prevent crash in <function>close_ps()</>

(the <type>point</> <literal>##</> <type>lseg</> operator)

for NaN input coordinates (Tom Lane)

</para>

<para>

Make it return NULL instead of crashing.

</para>

</listitem>

<listitem>

<para>

Avoid unsafe intermediate state during expensive paths

through <function>heap_update()</> (Masahiko Sawada, Andres Freund)

</para>

<para>

Previously, these cases locked the target tuple (by setting its XMAX)

but did not WAL-log that action, thus risking data integrity problems

if the page were spilled to disk and then a database crash occurred

before the tuple update could be completed.

</para>

</listitem>

<listitem>

<para>

Avoid consuming a transaction ID during <command>VACUUM</>

(Alexander Korotkov)

</para>

<para>

Some cases in <command>VACUUM</> unnecessarily caused an XID to be

assigned to the current transaction. Normally this is negligible,

but if one is up against the XID wraparound limit, consuming more

XIDs during anti-wraparound vacuums is a very bad thing.

</para>

</listitem>

<listitem>

<para>

Avoid canceling hot-standby queries during <command>VACUUM FREEZE</>

(Simon Riggs, &Aacute;lvaro Herrera)

</para>

<para>

<command>VACUUM FREEZE</> on an otherwise-idle master server could

result in unnecessary cancellations of queries on its standby

servers.

</para>

</listitem>

<listitem>

<para>

When a manual <command>ANALYZE</> specifies a column list, don't

reset the table's <literal>changes_since_analyze</> counter

(Tom Lane)

</para>

<para>

If we're only analyzing some columns, we should not prevent routine

auto-analyze from happening for the other columns.

</para>

</listitem>

<listitem>

<para>

Fix <command>ANALYZE</>'s overestimation of <literal>n_distinct</>

for a unique or nearly-unique column with many null entries (Tom

Lane)

</para>

<para>

The nulls could get counted as though they were themselves distinct

values, leading to serious planner misestimates in some types of

queries.

</para>

</listitem>

<listitem>

<para>

Prevent autovacuum from starting multiple workers for the same shared

catalog (&Aacute;lvaro Herrera)

</para>

<para>

Normally this isn't much of a problem because the vacuum doesn't take

long anyway; but in the case of a severely bloated catalog, it could

result in all but one worker uselessly waiting instead of doing

useful work on other tables.

</para>

</listitem>

<listitem>

<para>

Fix <filename>contrib/btree_gin</> to handle the smallest

possible <type>bigint</> value correctly (Peter Eisentraut)

</para>

</listitem>

<listitem>

<para>

Teach libpq to correctly decode server version from future servers

(Peter Eisentraut)

</para>

<para>

It's planned to switch to two-part instead of three-part server

version numbers for releases after 9.6. Make sure

that <function>PQserverVersion()</> returns the correct value for

such cases.

</para>

</listitem>

<listitem>

<para>

Fix <application>ecpg</>'s code for <literal>unsigned long long</>

array elements (Michael Meskes)

</para>

</listitem>

<listitem>

<para>

Make <application>pg_basebackup</> accept <literal>-Z 0</> as

specifying no compression (Fujii Masao)

</para>

</listitem>

<listitem>

<!--

Author: Tom Lane <tgl@sss.pgh.pa.us>

Branch: REL9_1_STABLE [d56c02f1a] 2016-06-19 13:45:03 -0400

Branch: REL9_1_STABLE [354b3a3ac] 2016-06-19 14:01:17 -0400

-->

<para>

Revert to the old heuristic timeout for <literal>pg_ctl start -w</>

(Tom Lane)

</para>

<para>

The new method adopted as of release 9.1.20 does not work

when <varname>silent_mode</> is enabled, so go back to the old way.

</para>

</listitem>

<listitem>

<para>

Fix makefiles' rule for building AIX shared libraries to be safe for

parallel make (Noah Misch)

</para>

</listitem>

<listitem>

<para>

Fix TAP tests and MSVC scripts to work when build directory's path

name contains spaces (Michael Paquier, Kyotaro Horiguchi)

</para>

</listitem>

<listitem>

<para>

Make regression tests safe for Danish and Welsh locales (Jeff Janes,

Tom Lane)

</para>

<para>

Change some test data that triggered the unusual sorting rules of

these locales.

</para>

</listitem>

<listitem>

<para>

Update our copy of the timezone code to match

IANA's <application>tzcode</> release 2016c (Tom Lane)

</para>

<para>

This is needed to cope with anticipated future changes in the time

zone data files. It also fixes some corner-case bugs in coping with

unusual time zones.

</para>

</listitem>

<listitem>

<para>

Update time zone data files to <application>tzdata</> release 2016f

for DST law changes in Kemerovo and Novosibirsk, plus historical

corrections for Azerbaijan, Belarus, and Morocco.

</para>

</listitem>

</itemizedlist>

</sect2>

</sect1>

<sect1 id="release-9-1-22">

<title>Release 9.1.22</title>