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 <sect1 id="release-9-3-2">
  <title>Release 9.3.2</title>

  <note>
  <title>Release Date</title>
  <simpara>2013-12-05</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.3.1.
   For information about new features in the 9.3 major release, see
   <xref linkend="release-9-3">.
  </para>

  <sect2>
   <title>Migration to Version 9.3.2</title>

   <para>
    A dump/restore is not required for those running 9.3.X.
   </para>

   <para>
    However, this release corrects a number of potential data corruption
    issues.  See the first three changelog entries below to find out whether
    your installation has been affected and what steps you can take if so.
   </para>

   <para>
    Also, if you are upgrading from a version earlier than 9.3.1,
    see <xref linkend="release-9-3-1">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix <command>VACUUM</>'s tests to see whether it can
      update <structfield>relfrozenxid</> (Andres Freund)
     </para>

     <para>
      In some cases <command>VACUUM</> (either manual or autovacuum) could
      incorrectly advance a table's <structfield>relfrozenxid</> value,
      allowing tuples to escape freezing, causing those rows to become
      invisible once 2^31 transactions have elapsed.  The probability of
      data loss is fairly low since multiple incorrect advancements would
      need to happen before actual loss occurs, but it's not zero.  In 9.2.0
      and later, the probability of loss is higher, and it's also possible
      to get <quote>could not access status of transaction</> errors as a
      consequence of this bug.  Users upgrading from releases 9.0.4 or 8.4.8
      or earlier are not affected, but all later versions contain the bug.
     </para>

     <para>
      The issue can be ameliorated by, after upgrading, vacuuming all tables
      in all databases while having <link
      linkend="guc-vacuum-freeze-table-age"><varname>vacuum_freeze_table_age</></link>
      set to zero.  This will fix any latent corruption but will not be able
      to fix all pre-existing data errors.  However, an installation can be
      presumed safe after performing this vacuuming if it has executed fewer
      than 2^31 update transactions in its lifetime (check this with
      <literal>SELECT txid_current() < 2^31</>).
     </para>
    </listitem>

    <listitem>
     <para>
      Fix multiple bugs in MultiXactId freezing (Andres Freund,
      &Aacute;lvaro Herrera)
     </para>

     <para>
      These bugs could lead to <quote>could not access status of
      transaction</> errors, or to duplicate or vanishing rows.
      Users upgrading from releases prior to 9.3.0 are not affected.
     </para>

     <para>
      The issue can be ameliorated by, after upgrading, vacuuming all tables
      in all databases while having <link
      linkend="guc-vacuum-freeze-table-age"><varname>vacuum_freeze_table_age</></link>
      set to zero.  This will fix latent corruption but will not be able to
      fix all pre-existing data errors.
     </para>

     <para>
      As a separate issue, these bugs can also cause standby servers to get
      out of sync with the primary, thus exhibiting data errors that are not
      in the primary.  Therefore, it's recommended that 9.3.0 and 9.3.1
      standby servers be re-cloned from the primary (e.g., with a new base
      backup) after upgrading.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix initialization of <filename>pg_clog</> and <filename>pg_subtrans</>
      during hot standby startup (Andres Freund, Heikki Linnakangas)
     </para>

     <para>
      This bug can cause data loss on standby servers at the moment they
      start to accept hot-standby queries, by marking committed transactions
      as uncommitted. The likelihood of such corruption is small unless, at
      the time of standby startup, the primary server has executed many
      updating transactions since its last checkpoint.  Symptoms include
      missing rows, rows that should have been deleted being still visible,
      and obsolete versions of updated rows being still visible alongside
      their newer versions.
     </para>

     <para>
      This bug was introduced in versions 9.3.0, 9.2.5, 9.1.10, and 9.0.14.
      Standby servers that have only been running earlier releases are not
      at risk.  It's recommended that standby servers that have ever run any
      of the buggy releases be re-cloned from the primary (e.g., with a new
      base backup) after upgrading.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix multiple bugs in update chain traversal (Andres Freund,
      &Aacute;lvaro Herrera)
     </para>

     <para>
      These bugs could result in incorrect behavior, such as locking or even
      updating the wrong row, in the presence of concurrent updates.
      Spurious <quote>unable to fetch updated version of tuple</> errors
      were also possible.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix dangling-pointer problem in fast-path locking (Tom Lane)
     </para>

     <para>
      This could lead to corruption of the lock data structures in shared
      memory, causing <quote>lock already held</> and other odd errors.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix assorted race conditions in timeout management (Tom Lane)
     </para>

     <para>
      These errors could result in a server process becoming unresponsive
      because it had blocked SIGALRM and/or SIGINT.
     </para>
    </listitem>

    <listitem>
     <para>
      Truncate <filename>pg_multixact</> contents during WAL replay
      (Andres Freund)
     </para>

     <para>
      This avoids ever-increasing disk space consumption in standby servers.
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure an anti-wraparound <command>VACUUM</> counts a page as scanned
      when it's only verified that no tuples need freezing (Sergey
      Burladyan, Jeff Janes)
     </para>

     <para>
      This bug could result in failing to
      advance <structfield>relfrozenxid</>, so that the table would still be
      thought to need another anti-wraparound vacuum.  In the worst case the
      database might even shut down to prevent wraparound.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix full-table-vacuum request mechanism for MultiXactIds (Andres Freund)
     </para>

     <para>
      This bug could result in large amounts of useless autovacuum activity.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race condition in GIN index posting tree page deletion (Heikki
      Linnakangas)
     </para>

     <para>
      This could lead to transient wrong answers or query failures.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <quote>unexpected spgdoinsert() failure</> error during SP-GiST
      index creation (Teodor Sigaev)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix assorted bugs in materialized views (Kevin Grittner, Andres Freund)
     </para>
    </listitem>

    <listitem>
     <para>
      Re-allow duplicate table aliases if they're within aliased JOINs
      (Tom Lane)
     </para>

     <para>
      Historically <productname>PostgreSQL</> has accepted queries like
<programlisting>
SELECT ... FROM tab1 x CROSS JOIN (tab2 x CROSS JOIN tab3 y) z
</programlisting>
      although a strict reading of the SQL standard would forbid the
      duplicate usage of table alias <literal>x</>.  A misguided change in
      9.3.0 caused it to reject some such cases that were formerly accepted.
      Restore the previous behavior.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid flattening a subquery whose <literal>SELECT</> list contains a
      volatile function wrapped inside a sub-<literal>SELECT</> (Tom Lane)
     </para>

     <para>
      This avoids unexpected results due to extra evaluations of the
      volatile function.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planner's processing of non-simple-variable subquery outputs
      nested within outer joins (Tom Lane)
     </para>

     <para>
      This error could lead to incorrect plans for queries involving
      multiple levels of subqueries within <literal>JOIN</> syntax.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect planning in cases where the same non-strict expression
      appears in multiple <literal>WHERE</> and outer <literal>JOIN</>
      equality clauses (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planner crash with whole-row reference to a subquery (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect generation of optimized MIN()/MAX() plans for
      inheritance trees (Tom Lane)
     </para>

     <para>
      The planner could fail in cases where the MIN()/MAX() argument was an
      expression rather than a simple variable.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix premature deletion of temporary files (Andres Freund)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent intra-transaction memory leak when printing range values
      (Tom Lane)
     </para>

     <para>
      This fix actually cures transient memory leaks in any datatype output
      function, but range types are the only ones known to have had a
      significant problem.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leaks when reloading configuration files (Heikki
      Linnakangas, Hari Babu)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent incorrect display of dropped columns in NOT NULL and CHECK
      constraint violation messages (Michael Paquier and Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow default arguments and named-argument notation for window
      functions (Tom Lane)
     </para>

     <para>
      Previously, these cases were likely to crash.
     </para>
    </listitem>

    <listitem>
     <para>
      Suppress trailing whitespace on each line when pretty-printing rules
      and views (Tom Lane)
     </para>

     <para>
      9.3.0 generated such whitespace in many more cases than previous
      versions did.  To reduce unexpected behavioral changes, suppress
      unnecessary whitespace in all cases.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible read past end of memory in rule printing (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix array slicing of <type>int2vector</> and <type>oidvector</> values
      (Tom Lane)
     </para>

     <para>
      Expressions of this kind are now implicitly promoted to
      regular <type>int2</> or <type>oid</> arrays.
     </para>
    </listitem>

    <listitem>
     <para>
      Return a valid JSON value when converting an empty <type>hstore</> value
      to <type>json</>
      (Oskari Saarenmaa)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect behaviors when using a SQL-standard, simple GMT offset
      timezone (Tom Lane)
     </para>

     <para>
      In some cases, the system would use the simple GMT offset value when
      it should have used the regular timezone setting that had prevailed
      before the simple offset was selected.  This change also causes
      the <function>timeofday</> function to honor the simple GMT offset
      zone.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent possible misbehavior when logging translations of Windows
      error codes (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Properly quote generated command lines in <application>pg_ctl</>
      (Naoya Anzai and Tom Lane)
     </para>

     <para>
      This fix applies only to Windows.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_dumpall</> to work when a source database
      sets <link
      linkend="guc-default-transaction-read-only"><varname>default_transaction_read_only</></link>
      via <command>ALTER DATABASE SET</> (Kevin Grittner)
     </para>

     <para>
      Previously, the generated script would fail during restore.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_isready</> to handle its <option>-d</> option
      properly (Fabr&iacute;zio de Royes Mello and Fujii Masao)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix parsing of WAL file names in <application>pg_receivexlog</>
      (Heikki Linnakangas)
     </para>

     <para>
      This error made <application>pg_receivexlog</> unable to restart
      streaming after stopping, once at least 4 GB of WAL had been written.
     </para>
    </listitem>

    <listitem>
     <para>
      Report out-of-disk-space failures properly
      in <application>pg_upgrade</> (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <application>ecpg</> search for quoted cursor names
      case-sensitively (Zolt&aacute;n B&ouml;sz&ouml;rm&eacute;nyi)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>ecpg</>'s processing of lists of variables
      declared <type>varchar</> (Zolt&aacute;n B&ouml;sz&ouml;rm&eacute;nyi)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <filename>contrib/lo</> defend against incorrect trigger definitions
      (Marc Cousin)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2013h
      for DST law changes in Argentina, Brazil, Jordan, Libya,
      Liechtenstein, Morocco, and Palestine.  Also, new timezone
      abbreviations WIB, WIT, WITA for Indonesia.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-3-1">
  <title>Release 9.3.1</title>

  <note>
  <title>Release Date</title>
  <simpara>2013-10-10</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.3.0.
   For information about new features in the 9.3 major release, see
   <xref linkend="release-9-3">.
  </para>

  <sect2>
   <title>Migration to Version 9.3.1</title>

   <para>
    A dump/restore is not required for those running 9.3.X.
   </para>

   <para>
    However, if you use the <literal>hstore</> extension, see the
    first changelog entry.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Ensure new-in-9.3 JSON functionality is added to the <literal>hstore</>
      extension during an update (Andrew Dunstan)
     </para>

     <para>
      Users who upgraded a pre-9.3 database containing <literal>hstore</>
      should execute
<programlisting>
ALTER EXTENSION hstore UPDATE;
</programlisting>
      after installing 9.3.1, to add two new JSON functions and a cast.
      (If <literal>hstore</> is already up to date, this command does
      nothing.)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak when creating B-tree indexes on range columns
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak caused by <function>lo_open()</function> failure
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Serializable snapshot fixes (Kevin Grittner, Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix deadlock bug in libpq when using SSL (Stephen Frost)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix timeline handling bugs in <application>pg_receivexlog</>
      (Heikki Linnakangas, Andrew Gierth)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent <command>CREATE FUNCTION</> from checking <command>SET</>
      variables unless function body checking is enabled (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove rare inaccurate warning during vacuum of index-less tables
      (Heikki Linnakangas)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-3">
  <title>Release 9.3</title>

  <note>
   <title>Release Date</title>
   <simpara>2013-09-09</simpara>
  </note>

  <sect2>
   <title>Overview</title>

   <para>
    Major enhancements in <productname>PostgreSQL</> 9.3 include:
   </para>

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

   <itemizedlist>

    <listitem>
     <para>
      Add <link linkend="SQL-CREATEMATERIALIZEDVIEW">materialized
      views</link>
     </para>
    </listitem>

    <listitem>
     <para>
      Make simple views <link
      linkend="SQL-CREATEVIEW-updatable-views">auto-updatable</link>
     </para>
    </listitem>

    <listitem>
     <para>
      Add many features for the <type>JSON</> data type,
      including <link linkend="functions-json">operators and functions</link>
      to extract elements from <type>JSON</> values
     </para>
    </listitem>

    <listitem>
     <para>
      Implement <acronym>SQL</>-standard <link
      linkend="queries-lateral"><literal>LATERAL</></link> option for
      <literal>FROM</>-clause subqueries and function calls
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <link linkend="SQL-CREATEFOREIGNDATAWRAPPER">foreign data
      wrappers</link> to support writes (inserts/updates/deletes) on foreign
      tables
     </para>
    </listitem>

    <listitem>
     <para>
      Add a <link linkend="postgres-fdw"><productname>Postgres</> foreign
      data wrapper</link> to allow access to
      other <productname>Postgres</> servers
     </para>
    </listitem>

    <listitem>
     <para>
      Add support for <link linkend="event-triggers">event triggers</link>
     </para>
    </listitem>

    <listitem>
     <para>
      Add optional ability to <link
      linkend="app-initdb-data-checksums">checksum</link> data pages and
      report corruption
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent non-key-field row updates from blocking foreign key checks
     </para>
    </listitem>

    <listitem>
     <para>
      Greatly reduce System V <link linkend="sysvipc">shared
      memory</link> requirements
     </para>
    </listitem>

   </itemizedlist>

   <para>
    The above items are explained in more detail in the sections below.
   </para>

  </sect2>

  <sect2>

  <title>Migration to Version 9.3</title>

   <para>
    A dump/restore using <link
    linkend="APP-PG-DUMPALL"><application>pg_dumpall</></link>, or use
    of <link linkend="pgupgrade"><application>pg_upgrade</></link>, is
    required for those wishing to migrate data from any previous release.
   </para>

   <para>
    Version 9.3 contains a number of changes that may affect compatibility
    with previous releases.  Observe the following incompatibilities:
   </para>

   <sect3>
    <title>Server Settings</title>

     <itemizedlist>

      <listitem>
       <para>
        Rename <varname>replication_timeout</> to <link
        linkend="guc-wal-sender-timeout"><varname>wal_sender_timeout</></link>
        (Amit Kapila)
       </para>

       <para>
        This setting controls the <link
        linkend="wal"><acronym>WAL</></link> sender timeout.
       </para>
      </listitem>

      <listitem>
       <para>
        Require superuser privileges to set <link
        linkend="guc-commit-delay"><varname>commit_delay</></link>
        because it can now potentially delay other sessions (Simon Riggs)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow in-memory sorts to use their full memory allocation (Jeff Janes)
       </para>

       <para>
        Users who have set <link
        linkend="guc-work-mem"><varname>work_mem</></link> based on the
        previous behavior may need to revisit that setting.
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Other</title>

     <itemizedlist>

      <listitem>
       <para>
        Throw an error if a tuple to be updated or deleted has already been
        updated or deleted by a <literal>BEFORE</> trigger (Kevin Grittner)
       </para>

       <para>
        Formerly, the originally-intended update was silently skipped,
        resulting in logical inconsistency since the trigger might have
        propagated data to other places based on the intended update.
        Now an error is thrown to prevent the inconsistent results from being
        committed.  If this change affects your application, the best solution
        is usually to move the data-propagation actions to
        an <literal>AFTER</> trigger.
       </para>

       <para>
        This error will also be thrown if a query invokes a volatile function
        that modifies rows that are later modified by the query itself.
        Such cases likewise previously resulted in silently skipping updates.
       </para>
      </listitem>

      <listitem>
       <para>
        Change multicolumn <link linkend="SQL-CREATETABLE"><literal>ON UPDATE
        SET NULL/SET DEFAULT</></link> foreign key actions to affect
        all columns of the constraint, not just those changed in the
        <command>UPDATE</> (Tom Lane)
       </para>

       <para>
        Previously, we would set only those referencing columns that
        correspond to referenced columns that were changed by
        the <command>UPDATE</>.  This was what was required by SQL-92,
        but more recent editions of the SQL standard specify the new behavior.
       </para>
      </listitem>

      <listitem>
       <para>
        Force cached plans to be replanned if the <link
        linkend="guc-search-path"><varname>search_path</></link> changes
        (Tom Lane)
       </para>

       <para>
        Previously, cached plans already generated in the current session were
        not redone if the query was re-executed with a
        new <varname>search_path</> setting, resulting in surprising behavior.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <link
        linkend="functions-formatting-table"><function>to_number()</></link>
        to properly handle a period used as a thousands separator (Tom Lane)
       </para>

       <para>
        Previously, a period was considered to be a decimal point even when
        the locale says it isn't and the <literal>D</> format code is used to
        specify use of the locale-specific decimal point.  This resulted in
        wrong answers if <literal>FM</> format was also used.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <literal>STRICT</> non-set-returning functions that have
        set-returning functions in their arguments to properly return null
        rows (Tom Lane)
       </para>

       <para>
        A null value passed to the strict function should result in a null
        output, but instead, that output row was suppressed entirely.
       </para>
      </listitem>

      <listitem>
       <para>
        Store <link linkend="wal"><acronym>WAL</></link> in a continuous
        stream, rather than skipping the last 16MB segment every 4GB
        (Heikki Linnakangas)
       </para>

       <para>
        Previously, <acronym>WAL</> files with names ending in <literal>FF</>
        were not used because of this skipping.  If you have <acronym>WAL</>
        backup or restore scripts that took this behavior into account, they
        will need to be adjusted.
       </para>
      </listitem>

      <listitem>
       <para>
        In <link
        linkend="catalog-pg-constraint"><structname>pg_constraint.confmatchtype</></link>,
        store the default foreign key match type (non-<literal>FULL</>,
        non-<literal>PARTIAL</>) as <literal>s</> for <quote>simple</>
        (Tom Lane)
       </para>

       <para>
        Previously this case was represented by <literal>u</>
        for <quote>unspecified</>.
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

  </sect2>

  <sect2>
   <title>Changes</title>

   <para>
    Below you will find a detailed account of the changes between
    <productname>PostgreSQL</productname> 9.3 and the previous major
    release.
   </para>

   <sect3>
    <title>Server</title>

    <sect4>
     <title>Locking</title>

     <itemizedlist>

      <listitem>
       <para>
        Prevent non-key-field row updates from blocking foreign key checks
        (&Aacute;lvaro Herrera, Noah Misch, Andres Freund, Alexander
        Shulgin, Marti Raudsepp, Alexander Shulgin)
       </para>

       <para>
        This change improves concurrency and reduces the probability of
        deadlocks when updating tables involved in a foreign-key constraint.
        <command>UPDATE</>s that do not change any columns referenced in a
        foreign key now take the new <literal>NO KEY UPDATE</> lock mode on
        the row, while foreign key checks use the new <literal>KEY SHARE</>
        lock mode, which does not conflict with <literal>NO KEY UPDATE</>.
        So there is no blocking unless a foreign-key column is changed.
       </para>
      </listitem>

      <listitem>
       <para>
        Add configuration variable <link
        linkend="guc-lock-timeout"><varname>lock_timeout</></link> to
        allow limiting how long a session will wait to acquire any one lock
        (Zolt&aacute;n B&ouml;sz&ouml;rm&eacute;nyi)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Indexes</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="rangetypes-indexing"><acronym>SP-GiST</></link>
        support for range data types (Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="GiST"><acronym>GiST</></link> indexes to be
        unlogged (Jeevan Chalke)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of <acronym>GiST</> index insertion by randomizing
        the choice of which page to descend to when there are multiple equally
        good alternatives (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve concurrency of hash index operations (Robert Haas)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Optimizer</title>

     <itemizedlist>

      <listitem>
       <para>
        Collect and use histograms of upper and lower bounds, as well as range
        lengths, for <link linkend="rangetypes">range types</link>
        (Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve optimizer's cost estimation for index access (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve optimizer's hash table size estimate for
        doing <literal>DISTINCT</> via hash aggregation (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Suppress no-op Result and Limit plan nodes
        (Kyotaro Horiguchi, Amit Kapila, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce optimizer overhead by not keeping plans on the basis of cheap
        startup cost when the optimizer only cares about total cost overall
        (Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>General Performance</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="SQL-COPY"><command>COPY FREEZE</></link>
        option to avoid the overhead of marking tuples as frozen later
        (Simon Riggs, Jeff Davis)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of <link
        linkend="datatype-numeric"><type>NUMERIC</></link> calculations
        (Kyotaro Horiguchi)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve synchronization of sessions waiting for <link
        linkend="guc-commit-delay"><varname>commit_delay</></link>
        (Peter Geoghegan)
       </para>

       <para>
        This greatly improves the usefulness of <varname>commit_delay</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of the <link
        linkend="SQL-CREATETABLE"><command>CREATE TEMPORARY TABLE ... ON
        COMMIT DELETE ROWS</></link> option by not truncating such temporary
        tables in transactions that haven't touched any temporary tables
        (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Make vacuum recheck visibility after it has removed expired tuples
        (Pavan Deolasee)
       </para>

       <para>
        This increases the chance of a page being marked as all-visible.
       </para>
      </listitem>

      <listitem>
       <para>
        Add per-resource-owner lock caches (Jeff Janes)
       </para>

       <para>
        This speeds up lock bookkeeping at statement completion in
        multi-statement transactions that hold many locks; it is particularly
        useful for <application>pg_dump</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Avoid scanning the entire relation cache at commit of a transaction
        that creates a new relation (Jeff Janes)
       </para>

       <para>
        This speeds up sessions that create many tables in successive
        small transactions, such as a <application>pg_restore</> run.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of transactions that drop many relations
        (Tomas Vondra)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Monitoring</title>

     <itemizedlist>

      <listitem>
       <para>
        Add optional ability to <link
        linkend="app-initdb-data-checksums">checksum</link> data pages and
        report corruption (Simon Riggs, Jeff Davis, Greg Smith, Ants Aasma)
       </para>

       <para>
        The checksum option can be set during <link
        linkend="APP-INITDB">initdb</link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Split the <link linkend="monitoring-stats">statistics collector's</link>
        data file into separate global and per-database files (Tomas Vondra)
       </para>

       <para>
        This reduces the I/O required for statistics tracking.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix the statistics collector to operate properly in cases where the
        system clock goes backwards (Tom Lane)
       </para>

       <para>
        Previously, statistics collection would stop until the time again
        reached the latest time previously recorded.
       </para>
      </listitem>

      <listitem>
       <para>
        Emit an informative message to postmaster standard error when we
        are about to stop logging there
        (Tom Lane)
       </para>

       <para>
        This should help reduce user confusion about where to look for log
        output in common configurations that log to standard error only during
        postmaster startup.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Authentication</title>

     <itemizedlist>

      <listitem>
       <para>
        When an authentication failure occurs, log the relevant
        <link linkend="auth-pg-hba-conf"><filename>pg_hba.conf</></link>
        line, to ease debugging of unintended failures
        (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <link linkend="auth-ldap"><acronym>LDAP</></link> error
        reporting and documentation (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for specifying <acronym>LDAP</> authentication parameters
        in <acronym>URL</> format, per RFC 4516 (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Change the <link
        linkend="guc-ssl-ciphers"><varname>ssl_ciphers</></link> parameter
        to start with <literal>DEFAULT</>, rather than <literal>ALL</>,
        then remove insecure ciphers (Magnus Hagander)
       </para>

       <para>
        This should yield a more appropriate SSL cipher set.
       </para>
      </listitem>

      <listitem>
       <para>
        Parse and load <link
        linkend="auth-username-maps"><filename>pg_ident.conf</></link>
        once, not during each connection (Amit Kapila)
       </para>

       <para>
        This is similar to how <filename>pg_hba.conf</> is processed.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Server Settings</title>

     <itemizedlist>

      <listitem>
       <para>
        Greatly reduce System V <link linkend="sysvipc">shared
        memory</link> requirements (Robert Haas)
       </para>

       <para>
        On Unix-like systems, <function>mmap()</> is now used for most
        of <productname>PostgreSQL</>'s shared memory.  For most users, this
        will eliminate any need to adjust kernel parameters for shared memory.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow the postmaster to listen on multiple Unix-domain sockets
        (Honza Hor&aacute;k)
       </para>

       <para>
        The configuration parameter
        <varname>unix_socket_directory</> is replaced by <link
        linkend="guc-unix-socket-directories"><varname>unix_socket_directories</></link>,
        which accepts a list of directories.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow a directory of configuration files to be processed (Magnus
        Hagander, Greg Smith, Selena Deckelmann)
       </para>

       <para>
        Such a directory is specified with <link
        linkend="config-includes"><varname>include_dir</></link> in the server
        configuration file.
       </para>
      </listitem>

      <listitem>
       <para>
        Increase the maximum <link
        linkend="APP-INITDB">initdb</link>-configured value for <link
        linkend="guc-shared-buffers"><varname>shared_buffers</></link>
        to 128MB (Robert Haas)
       </para>

       <para>
        This is the maximum value that initdb will attempt to set in <link
        linkend="config-setting-configuration-file"><filename>postgresql.conf</></link>;
        the previous maximum was 32MB.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove the <link linkend="guc-external-pid-file">external
        <acronym>PID</> file</link>, if any, on postmaster exit
        (Peter Eisentraut)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Replication and Recovery</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow a streaming replication standby to <link
        linkend="protocol-replication">follow a timeline switch</link>
        (Heikki Linnakangas)
       </para>

       <para>
        This allows streaming standby servers to receive WAL data from a slave
        newly promoted to master status.  Previously, other standbys would
        require a resync to begin following the new master.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>SQL</> functions <link
        linkend="functions-admin-backup"><function>pg_is_in_backup()</></link>
        and <link
        linkend="functions-admin-backup"><function>pg_backup_start_time()</></link>
        (Gilles Darold)
       </para>

       <para>
        These functions report the status of base backups.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of streaming log shipping with <link
        linkend="guc-synchronous-commit"><varname>synchronous_commit</></link>
        disabled (Andres Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow much faster promotion of a streaming standby to primary (Simon
        Riggs, Kyotaro Horiguchi)
       </para>
      </listitem>

      <listitem>
       <para>
        Add the last checkpoint's redo location to <link
        linkend="APP-PGCONTROLDATA"><application>pg_controldata</></link>'s
        output (Fujii Masao)
       </para>

       <para>
        This information is useful for determining which <acronym>WAL</>
        files are needed for restore.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow tools like <link
        linkend="app-pgreceivexlog"><application>pg_receivexlog</></link>
        to run on computers with different architectures (Heikki
        Linnakangas)
       </para>

       <para>
        WAL files can still only be replayed on servers with the same
        architecture as the primary; but they can now be transmitted to and
        stored on machines of any architecture, since the
        streaming replication protocol is now machine-independent.
       </para>
      </listitem>

      <listitem>
       <para>
        Make <link
        linkend="app-pgbasebackup"><application>pg_basebackup</></link>
        <option>--write-recovery-conf</> output a
        minimal <filename>recovery.conf</> file (Zolt&aacute;n
        B&ouml;sz&ouml;rm&eacute;nyi, Magnus Hagander)
       </para>

       <para>
        This simplifies setting up a standby server.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link
        linkend="app-pgreceivexlog"><application>pg_receivexlog</></link>
        and <link
        linkend="app-pgbasebackup"><application>pg_basebackup</></link>
        <option>--xlog-method</> to handle streaming timeline switches
        (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="guc-wal-receiver-timeout"><varname>wal_receiver_timeout</></link>
        parameter to control the <acronym>WAL</> receiver's timeout
        (Amit Kapila)
       </para>

       <para>
        This allows more rapid detection of connection failure.
       </para>
      </listitem>

      <listitem>
       <para>
        Change the <link linkend="wal"><acronym>WAL</></link> record format to
        allow splitting the record header across pages (Heikki Linnakangas)
       </para>

       <para>
        The new format is slightly more compact, and is more efficient to
        write.
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Queries</title>

     <itemizedlist>

      <listitem>
       <para>
        Implement <acronym>SQL</>-standard <link
        linkend="queries-lateral"><literal>LATERAL</></link> option for
        <literal>FROM</>-clause subqueries and function calls (Tom Lane)
       </para>

       <para>
        This feature allows subqueries and functions in <literal>FROM</> to
        reference columns from other tables in the <literal>FROM</>
        clause. The <literal>LATERAL</> keyword is optional for functions.
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for piping <link
        linkend="SQL-COPY"><command>COPY</></link> and <link
        linkend="APP-PSQL"><application>psql</></link> <command>\copy</>
        data to/from an external program (Etsuro Fujita)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow a multirow <link
        linkend="SQL-VALUES"><literal>VALUES</></link> clause in a rule
        to reference <literal>OLD</>/<literal>NEW</> (Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Object Manipulation</title>

     <itemizedlist>

      <listitem>
       <para>
        Add support for <link linkend="event-triggers">event triggers</link>
        (Dimitri Fontaine, Robert Haas, &Aacute;lvaro Herrera)
       </para>

       <para>
        This allows server-side functions written in event-enabled
        languages to be called when DDL commands are run.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="SQL-CREATEFOREIGNDATAWRAPPER">foreign data
        wrappers</link> to support writes (inserts/updates/deletes) on foreign
        tables (KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="SQL-CREATESCHEMA"><command>CREATE SCHEMA ... IF
        NOT EXISTS</></link> clause (Fabr&iacute;zio de Royes Mello)
       </para>
      </listitem>

      <listitem>
       <para>
        Make <link linkend="SQL-REASSIGN-OWNED"><command>REASSIGN
        OWNED</></link> also change ownership of shared objects
        (&Aacute;lvaro Herrera)
       </para>
      </listitem>

      <listitem>
       <para>
        Make <link linkend="sql-createaggregate"><command>CREATE
        AGGREGATE</></link> complain if the given initial value string is not
        valid input for the transition datatype (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Suppress <link linkend="SQL-CREATETABLE"><command>CREATE
        TABLE</></link>'s messages about implicit index and sequence creation
        (Robert Haas)
       </para>

       <para>
        These messages now appear at <literal>DEBUG1</> verbosity, so that
        they will not be shown by default.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="SQL-DROPTABLE"><command>DROP TABLE IF
        EXISTS</></link> to succeed when a non-existent schema is specified
        in the table name (Bruce Momjian)
       </para>

       <para>
         Previously, it threw an error if the schema did not exist.
       </para>
      </listitem>

      <listitem>
       <para>
        Provide clients with <link
        linkend="libpq-pqresulterrorfield">constraint violation details</link>
        as separate fields (Pavel Stehule)
       </para>

       <para>
        This allows clients to retrieve table, column, data type, or
        constraint name error details.  Previously such information had to be
        extracted from error strings.  Client library support is required to
        access these fields.
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title><command>ALTER</></title>

     <itemizedlist>

      <listitem>
       <para>
        Support <literal>IF NOT EXISTS</> option in <link
        linkend="SQL-ALTERTYPE"><command>ALTER TYPE ... ADD VALUE</></link>
        (Andrew Dunstan)
       </para>

       <para>
        This is useful for conditionally adding values to enumerated types.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="SQL-ALTERROLE"><command>ALTER ROLE ALL
        SET</></link> to establish settings for all users (Peter Eisentraut)
       </para>

       <para>
        This allows settings to apply to all users in all databases. <link
        linkend="SQL-ALTERDATABASE"><command>ALTER DATABASE SET</></link>
        already allowed addition of settings for all users in a single
        database.  <filename>postgresql.conf</> has a similar effect.
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for <link linkend="SQL-ALTERRULE"><command>ALTER RULE
        ... RENAME</></link> (Ali Dar)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="rules-views"><command>VIEWs</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="SQL-CREATEMATERIALIZEDVIEW">materialized
        views</link> (Kevin Grittner)
       </para>

       <para>
        Unlike ordinary views, where the base tables are read on every access,
        materialized views create physical tables at creation or refresh time.
        Access to the materialized view then reads from its physical
        table. There is not yet any facility for incrementally refreshing
        materialized views or auto-accessing them via base table access.
       </para>
      </listitem>

      <listitem>
       <para>
        Make simple views <link
        linkend="SQL-CREATEVIEW-updatable-views">auto-updatable</link>
        (Dean Rasheed)
       </para>

       <para>
        Simple views that reference some or all columns from a
        single base table are now updatable by default. More
        complex views can be made updatable using <link
        linkend="SQL-CREATETRIGGER"><literal>INSTEAD OF</></link> triggers
        or <link linkend="SQL-CREATERULE"><literal>INSTEAD</></link> rules.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="SQL-CREATEVIEW"><command>CREATE RECURSIVE
        VIEW</></link> syntax (Peter Eisentraut)
       </para>

       <para>
        Internally this is translated into <command>CREATE VIEW ... WITH
        RECURSIVE ...</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve view/rule printing code to handle cases where referenced
        tables are renamed, or columns are renamed, added, or dropped
        (Tom Lane)
       </para>

       <para>
        Table and column renamings can produce cases where, if we merely
        substitute the new name into the original text of a rule or view, the
        result is ambiguous.  This change fixes the rule-dumping code to insert
        manufactured table and column aliases when needed to preserve the
        original semantics.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Data Types</title>

    <itemizedlist>

      <listitem>
       <para>
        Increase the maximum size of <link linkend="largeObjects">large
        objects</link> from 2GB to 4TB (Nozomi Anzai, Yugo Nagata)
       </para>

       <para>
        This change includes adding 64-bit-capable large object access
        functions, both in the server and in libpq.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow text <link linkend="datatype-timezones">timezone
        designations</link>, e.g. <quote>America/Chicago</>, in the
        <quote>T</> field of <acronym>ISO</>-format <type>timestamptz</type>
        input (Bruce Momjian)
       </para>
      </listitem>

    </itemizedlist>

   <sect4>
    <title><link linkend="datatype-json"><type>JSON</></link></title>

    <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="functions-json">operators and functions</link>
        to extract elements from <type>JSON</> values (Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <type>JSON</> values to be <link
        linkend="functions-json-table">converted into records</link>
        (Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="functions-json-table">functions</link> to convert
        scalars, records, and <type>hstore</> values to <type>JSON</> (Andrew
        Dunstan)
       </para>
      </listitem>

    </itemizedlist>

   </sect4>

   </sect3>


   <sect3>
    <title>Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link
        linkend="array-functions-table"><function>array_remove()</></link>
        and <link
        linkend="array-functions-table"><function>array_replace()</></link>
        functions (Marco Nenciarini, Gabriele Bartolini)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link
        linkend="functions-string-other"><function>concat()</></link>
        and <link
        linkend="functions-string-format"><function>format()</></link>
        to properly expand <literal>VARIADIC</>-labeled arguments
        (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <link
        linkend="functions-string-format"><function>format()</></link>
        to provide field width and left/right alignment options (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Make <link
        linkend="functions-formatting-table"><function>to_char()</></link>,
        <link
        linkend="functions-formatting-table"><function>to_date()</></link>,
        and <link
        linkend="functions-formatting-table"><function>to_timestamp()</></link>
        handle negative (BC) century values properly
        (Bruce Momjian)
       </para>

       <para>
        Previously the behavior was either wrong or inconsistent
        with positive/<acronym>AD</> handling, e.g. with the format mask
        <quote>IYYY-IW-DY</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Make <link
        linkend="functions-formatting-table"><function>to_date()</></link>
        and <link
        linkend="functions-formatting-table"><function>to_timestamp()</></link>
        return proper results when mixing <acronym>ISO</> and Gregorian
        week/day designations (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Cause <link
        linkend="functions-info-catalog-table"><function>pg_get_viewdef()</></link>
        to start a new line by default after each <literal>SELECT</> target
        list entry and <literal>FROM</> entry (Marko Tiikkaja)
       </para>

       <para>
        This reduces line length in view printing, for instance in <link
        linkend="APP-PGDUMP"><application>pg_dump</></link> output.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <function>map_sql_value_to_xml_value()</> to print values of
        domain types the same way their base type would be printed
        (Pavel Stehule)
       </para>

       <para>
        There are special formatting rules for certain built-in types such as
        <type>boolean</>; these rules now also apply to domains over these
        types.
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Server-Side Languages</title>

    <sect4>
     <title><link linkend="plpgsql">PL/pgSQL</link> Server-Side Language</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow PL/pgSQL to use <literal>RETURN</> with a composite-type
        expression (Asif Rehman)
       </para>

       <para>
        Previously, in a function returning a composite type,
        <literal>RETURN</> could only reference a variable of that type.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow PL/pgSQL to access <link
        linkend="plpgsql-exception-diagnostics">constraint violation
        details</link> as separate fields (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow PL/pgSQL to access the number of rows processed by
        <link linkend="SQL-COPY"><command>COPY</></link> (Pavel Stehule)
       </para>

       <para>
        A <command>COPY</> executed in a PL/pgSQL function now updates the
        value retrieved by <link
        linkend="plpgsql-statements-diagnostics"><command>GET DIAGNOSTICS
        x = ROW_COUNT</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow unreserved keywords to be used as identifiers everywhere in
        PL/pgSQL (Tom Lane)
       </para>

       <para>
        In certain places in the PL/pgSQL grammar, keywords had to be quoted
        to be used as identifiers, even if they were nominally unreserved.
       </para>
      </listitem>

    </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="plpython">PL/Python</link> Server-Side Language</title>

     <itemizedlist>

      <listitem>
       <para>
        Add PL/Python result object string handler (Peter Eisentraut)
       </para>

       <para>
        This allows <literal>plpy.debug(rv)</literal> to output something reasonable.
       </para>
      </listitem>

      <listitem>
       <para>
        Make PL/Python convert OID values to a proper Python numeric type
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Handle <link linkend="spi"><acronym>SPI</></link> errors raised
        explicitly (with PL/Python's <literal>RAISE</>) the same as
        internal <acronym>SPI</> errors (Oskari Saarenmaa and Jan Urbanski)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Server Programming Interface (<link linkend="spi">SPI</link>)</title>

     <itemizedlist>

      <listitem>
       <para>
        Prevent leakage of <acronym>SPI</> tuple tables during subtransaction
        abort (Tom Lane)
       </para>

       <para>
        At the end of any failed subtransaction, the core SPI code now
        releases any SPI tuple tables that were created during that
        subtransaction.  This avoids the need for SPI-using code to keep track
        of such tuple tables and release them manually in error-recovery code.
        Failure to do so caused a number of transaction-lifespan memory leakage
        issues in PL/pgSQL and perhaps other SPI clients.  <link
        linkend="spi-spi-freetupletable"><function>SPI_freetuptable()</></link>
        now protects itself against multiple freeing requests, so any existing
        code that did take care to clean up shouldn't be broken by this change.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <acronym>SPI</> functions to access the number of rows processed
        by <link linkend="SQL-COPY"><command>COPY</></link> (Pavel Stehule)
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Client Applications</title>

    <itemizedlist>

      <listitem>
       <para>
        Add command-line utility <link
        linkend="app-pg-isready"><application>pg_isready</></link> to
        check if the server is ready to accept connections (Phil Sorber)
       </para>
      </listitem>

      <listitem>
       <para>
        Support multiple <option>--table</> arguments for <link
        linkend="APP-PGRESTORE"><application>pg_restore</></link>,
        <link linkend="APP-CLUSTERDB"><application>clusterdb</></link>,
        <link linkend="APP-REINDEXDB"><application>reindexdb</></link>,
        and <link linkend="APP-VACUUMDB"><application>vacuumdb</></link>
        (Josh Kupershmidt)
       </para>

       <para>
        This is similar to the way <link
        linkend="APP-PGDUMP"><application>pg_dump</></link>'s
        <option>--table</> option works.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <option>--dbname</> option to <link
        linkend="APP-PG-DUMPALL"><application>pg_dumpall</></link>, <link
        linkend="app-pgbasebackup"><application>pg_basebackup</></link>, and
        <link
        linkend="app-pgreceivexlog"><application>pg_receivexlog</></link>
        to allow specifying a connection string (Amit Kapila)
       </para>
      </listitem>

      <listitem>
       <para>
        Add libpq function <link
        linkend="libpq-pqconninfo"><function>PQconninfo()</></link>
        to return connection information (Zolt&aacute;n
        B&ouml;sz&ouml;rm&eacute;nyi, Magnus Hagander)
       </para>
      </listitem>

    </itemizedlist>

    <sect4>
     <title><link linkend="APP-PSQL"><application>psql</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Adjust function cost settings so <application>psql</> tab
        completion and pattern searching are more efficient (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <application>psql</>'s tab completion coverage (Jeff Janes,
        Dean Rasheed, Peter Eisentraut, Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow the <application>psql</> <option>--single-transaction</>
        mode to work when reading from standard input (Fabien Coelho,
        Robert Haas)
       </para>

       <para>
        Previously this option only worked when reading from a file.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <application>psql</> warning when connecting to an older
        server (Peter Eisentraut)
       </para>

       <para>
        A warning is still issued when connecting to a server of a newer major
        version than <application>psql</>'s.
       </para>
      </listitem>

     </itemizedlist>

    <sect5>
     <title><link linkend="APP-PSQL-meta-commands">Backslash Commands</link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <application>psql</> command <command>\watch</> to repeatedly
        execute a SQL command (Will Leinweber)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <application>psql</> command <command>\gset</> to store query
        results in <application>psql</> variables (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>SSL</> information to <application>psql</>'s
        <command>\conninfo</> command (Alastair Turner)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <quote>Security</> column to <application>psql</>'s
        <command>\df+</> output (Jon Erdman)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>psql</> command <command>\l</> to accept a database
        name pattern (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        In <application>psql</>, do not allow <command>\connect</> to
        use defaults if there is no active connection (Bruce Momjian)
       </para>

       <para>
        This might be the case if the server had crashed.
       </para>
      </listitem>

      <listitem>
       <para>
        Properly reset state after failure of a SQL command executed with
        <application>psql</>'s <literal>\g</> <replaceable>file</>
        (Tom Lane)
       </para>

       <para>
        Previously, the output from subsequent SQL commands would unexpectedly
        continue to go to the same file.
       </para>
      </listitem>

     </itemizedlist>

    </sect5>

    <sect5>
     <title>Output</title>

     <itemizedlist>

      <listitem>
       <para>
        Add a <literal>latex-longtable</> output format to
        <application>psql</> (Bruce Momjian)
       </para>

       <para>
        This format allows tables to span multiple pages.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <literal>border=3</> output mode to the <application>psql</>
        <literal>latex</> format (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        In <application>psql</>'s tuples-only and expanded output modes, no
        longer emit <quote>(No rows)</> for zero rows (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        In <application>psql</>'s unaligned, expanded output mode, no longer
        print an empty line for zero rows (Peter Eisentraut)
       </para>
      </listitem>

     </itemizedlist>

    </sect5>

    </sect4>

    <sect4>
     <title><link linkend="APP-PGDUMP"><application>pg_dump</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <application>pg_dump</> <option>--jobs</> option to dump tables in
        parallel (Joachim Wieland)
       </para>
      </listitem>

      <listitem>
       <para>
        Make <application>pg_dump</> output functions in a more predictable
        order (Joel Jacobson)
       </para>
      </listitem>

      <listitem>
       <para>
        Fix tar files emitted by <application>pg_dump</>
        to be <acronym>POSIX</> conformant (Brian Weaver, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <option>--dbname</> option to <application>pg_dump</>, for
        consistency with other client commands (Heikki Linnakangas)
       </para>

       <para>
        The database name could already be supplied last without a flag.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="APP-INITDB"><application>initdb</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Make initdb fsync the newly created data directory (Jeff Davis)
       </para>

       <para>
        This insures data integrity in event of a system crash shortly after
        initdb.  This can be disabled by using <option>--nosync</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add initdb <option>--sync-only</> option to sync the data directory to durable
        storage (Bruce Momjian)
       </para>

       <para>
        This is used by <link
        linkend="pgupgrade"><application>pg_upgrade</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Make initdb issue a warning about placing the data directory at the
        top of a file system mount point (Bruce Momjian)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Source Code</title>

     <itemizedlist>

      <listitem>
       <para>
        Add infrastructure to allow plug-in <link
        linkend="bgworker">background worker processes</link>
        (&Aacute;lvaro Herrera)
       </para>
      </listitem>

      <listitem>
       <para>
        Create a centralized timeout <acronym>API</> (Zolt&aacute;n
        B&ouml;sz&ouml;rm&eacute;nyi)
       </para>
      </listitem>

      <listitem>
       <para>
        Create libpgcommon and move <function>pg_malloc()</> and other
        functions there (&Aacute;lvaro Herrera, Andres Freund)
       </para>

       <para>
        This allows libpgport to be used solely for portability-related code.
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for list links embedded in larger structs (Andres Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Use <literal>SA_RESTART</> for all signals,
        including <literal>SIGALRM</> (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Ensure that the correct text domain is used when
        translating <function>errcontext()</> messages
        (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Standardize naming of client-side memory allocation functions (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Provide support for <quote>static assertions</> that will fail at
        compile time if some compile-time-constant condition is not met
        (Andres Freund, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Support <function>Assert()</> in client-side code (Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Add decoration to inform the C compiler that some <function>ereport()</>
        and <function>elog()</> calls do not return (Peter Eisentraut,
        Andres Freund, Tom Lane, Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow options to be passed to the regression
        test output comparison utility via <link
        linkend="regress-evaluation"><envar>PG_REGRESS_DIFF_OPTS</></link>
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add isolation tests for <link
        linkend="SQL-CREATEINDEX"><command>CREATE INDEX
        CONCURRENTLY</></link> (Abhijit Menon-Sen)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove typedefs for <type>int2</>/<type>int4</> as they are better
        represented as <type>int16</>/<type>int32</> (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <link linkend="install">install-strip</link> on Mac <productname>OS
        X</> (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <link linkend="configure">configure</link> flag
        <option>--disable-shared</>, as it is no longer supported
        (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Rewrite pgindent in <application>Perl</> (Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Provide Emacs macro to set Perl formatting to
        match <productname>PostgreSQL</>'s perltidy settings (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Run tool to check the keyword list whenever the backend grammar is
        changed (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Change the way <literal>UESCAPE</> is lexed, to significantly reduce
        the size of the lexer tables (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Centralize <application>flex</> and <application>bison</>
        <application>make</> rules (Peter Eisentraut)
       </para>

       <para>
        This is useful for <application>pgxs</> authors.
       </para>
      </listitem>

      <listitem>
       <para>
        Change many internal backend functions to return object <type>OID</>s
        rather than void (Dimitri Fontaine)
       </para>

       <para>
        This is useful for event triggers.
       </para>
      </listitem>

      <listitem>
       <para>
        Invent pre-commit/pre-prepare/pre-subcommit events for transaction
        callbacks (Tom Lane)
       </para>

       <para>
        Loadable modules that use transaction callbacks might need modification
        to handle these new event types.
       </para>
      </listitem>

      <listitem>
       <para>
        Add function <link
        linkend="functions-info-catalog-table"><function>pg_identify_object()</></link>
        to produce a machine-readable description of a database object
        (&Aacute;lvaro Herrera)
       </para>
      </listitem>

      <listitem>
       <para>
        Add post-<command>ALTER</>-object server hooks (KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
        Implement a generic binary heap and use it for Merge-Append
        operations (Abhijit Menon-Sen)
       </para>
      </listitem>

      <listitem>
       <para>
        Provide a tool to help detect timezone abbreviation changes when
        updating the <filename>src/timezone/data</> files
        (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <application>pkg-config</> support for <application>libpq</>
        and <application>ecpg</> libraries (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <filename>src/tool/backend</>, now that the content is on
        the <productname>PostgreSQL</> wiki (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Split out <link linkend="wal"><acronym>WAL</></link> reading as
        an independent facility (Heikki Linnakangas, Andres Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Use a 64-bit integer to represent <link
        linkend="wal"><acronym>WAL</></link> positions
        (<structname>XLogRecPtr</>) instead of two 32-bit integers
        (Heikki Linnakangas)
       </para>

       <para>
        Generally, tools that need to read the <acronym>WAL</> format
        will need to be adjusted.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="plpython">PL/Python</link> to support
        platform-specific include directories (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="plpython">PL/Python</link> on <productname>OS
        X</> to build against custom versions of <application>Python</>
        (Peter Eisentraut)
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Additional Modules</title>

    <itemizedlist>

      <listitem>
       <para>
        Add a <link linkend="postgres-fdw"><productname>Postgres</> foreign
        data wrapper</link> contrib module to allow access to
        other <productname>Postgres</> servers (Shigeru Hanada)
       </para>

       <para>
        This foreign data wrapper supports writes.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="pgxlogdump"><application>pg_xlogdump</></link>
        contrib program (Andres Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for indexing of regular-expression searches in
        <link linkend="pgtrgm"><productname>pg_trgm</></link>
        (Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <link linkend="pgtrgm"><productname>pg_trgm</></link>'s
        handling of multibyte characters (Tom Lane)
       </para>

       <para>
        On a platform that does not have the wcstombs() or towlower() library
        functions, this could result in an incompatible change in the contents
        of <productname>pg_trgm</> indexes for non-ASCII data.  In such cases,
        <command>REINDEX</> those indexes to ensure correct search results.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <link linkend="pgstattuple">pgstattuple</link> function to report
        the size of the pending-insertions list of a <acronym>GIN</> index
        (Fujii Masao)
       </para>
      </listitem>

      <listitem>
       <para>
        Make <link linkend="oid2name"><application>oid2name</></link>,
        <link linkend="pgbench"><application>pgbench</></link>, and
        <link linkend="vacuumlo"><application>vacuumlo</></link> set
        <varname>fallback_application_name</> (Amit Kapila)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve output of <link
        linkend="pgtesttiming"><application>pg_test_timing</></link>
        (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve output of <link
        linkend="pgtestfsync"><application>pg_test_fsync</></link>
        (Peter Geoghegan)
       </para>
      </listitem>

      <listitem>
       <para>
        Create a dedicated foreign data wrapper, with its own option validator
        function, for <link linkend="dblink">dblink</link> (Shigeru Hanada)
       </para>

       <para>
        When using this FDW to define the target of a <application>dblink</>
        connection, instead of using a hard-wired list of connection options,
        the underlying <application>libpq</> library is consulted to see what
        connection options it supports.
       </para>
      </listitem>

    </itemizedlist>

    <sect4>
     <title><link linkend="pgupgrade"><application>pg_upgrade</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Allow <application>pg_upgrade</> to do dumps and restores in
        parallel (Bruce Momjian, Andrew Dunstan)
       </para>

       <para>
        This allows parallel schema dump/restore of databases, as well as
        parallel copy/link of data files per tablespace.  Use the
        <option>--jobs</> option to specify the level of parallelism.
       </para>
      </listitem>

      <listitem>
       <para>
        Make <application>pg_upgrade</> create Unix-domain sockets in
        the current directory (Bruce Momjian, Tom Lane)
       </para>

       <para>
        This reduces the possibility that someone will accidentally connect
        during the upgrade.
       </para>
      </listitem>

      <listitem>
       <para>
        Make <application>pg_upgrade</> <option>--check</> mode properly
        detect the location of non-default socket directories (Bruce
        Momjian, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of <application>pg_upgrade</> for databases
        with many tables (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <application>pg_upgrade</>'s logs by showing
        executed commands (&Aacute;lvaro Herrera)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <application>pg_upgrade</>'s status display during
        copy/link (Bruce Momjian)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="pgbench"><application>pgbench</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <option>--foreign-keys</> option to <application>pgbench</>
        (Jeff Janes)
       </para>

       <para>
        This adds foreign key constraints to the standard tables created by
        <application>pgbench</>, for use in foreign key performance testing.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pgbench</> to aggregate performance statistics
        and produce output every <option>--aggregate-interval</>
        seconds (Tomas Vondra)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <application>pgbench</> <option>--sampling-rate</> option
        to control the percentage of transactions logged (Tomas Vondra)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce and improve the status message output of
        <application>pgbench</>'s initialization mode (Robert Haas,
        Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <application>pgbench</> <option>-q</> mode to print one output
        line every five seconds (Tomas Vondra)
       </para>
      </listitem>

      <listitem>
       <para>
        Output <application>pgbench</> elapsed and estimated remaining
        time during initialization (Tomas Vondra)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pgbench</> to use much larger scale factors,
        by changing relevant columns from <type>integer</> to <type>bigint</>
        when the requested scale factor exceeds 20000
        (Greg Smith)
       </para>
      </listitem>

    </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Documentation</title>

    <itemizedlist>

      <listitem>
       <para>
        Allow <productname>EPUB</>-format documentation to be created
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Update <productname>FreeBSD</> kernel configuration documentation
        (Brad Davis)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <link linkend="tutorial-window"><literal>WINDOW</>
        function</link> documentation (Bruce Momjian, Florian Pflug)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="docguide-toolsets">instructions</link> for setting
        up the documentation tool chain on Mac <productname>OS X</>
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <link
        linkend="guc-commit-delay"><varname>commit_delay</></link>
        documentation (Peter Geoghegan)
       </para>
      </listitem>

    </itemizedlist>

   </sect3>

  </sect2>
 </sect1>
