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 <sect1 id="release-9-1">
  <title>Release 9.1</title>

  <note>
   <title>Release Date</title>
   <simpara>2011-??-??</simpara>
  </note>

  <para>CURRENT AS OF 2011-03-15</para>

  <sect2>
   <title>Overview</title>

   <para>
    This release of
    <productname>PostgreSQL</> adds numerous major features, including:
   </para>

   <para>
    (summary to be added)
   </para>

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

  </sect2>

  <sect2>

  <title>Migration to Version 9.1</title>

   <para>
    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>
    Version 9.1 contains a number of changes that may affect compatibility
    with previous releases.  Observe the following incompatibilities:
   </para>

   <sect3>
    <title>Strings</title>

    <itemizedlist>

     <listitem>
      <para>
       Change the default value of <link
       linkend="guc-standard-conforming-strings"><varname>standard_conforming_strings</></link>
       to on (Robert Haas)
      </para>

      <para>
       By default, backslashes are now ordinary characters in string literals,
       not escape characters.  This change removes a long-standing
       incompatibility with the SQL standard.  <link
       linkend="guc-escape-string-warning"><varname>escape_string_warning</></link>
       has produced warnings about this usage for years.  <literal>E''</>
       strings are the proper way to embed backslash escapes in strings and are
       unaffected by this change.
      </para>
     </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Casting</title>

    <itemizedlist>

     <listitem>
      <para>
       Disallow function-style and attribute-style data type casts for
       composite types (Tom Lane)
      </para>

      <para>
       For example, disallow
       <literal><replaceable>composite_value</>.text</literal> and
       <literal>text(<replaceable>composite_value</>)</literal>.
       The <literal>CAST</> and <literal>::</> syntaxes are still available
       for use when a cast of an entire composite value is actually intended.
      </para>
     </listitem>

     <listitem>
      <para>
       Tighten casting checks for domains based on arrays (Tom Lane)
      </para>

      <para>
       When a domain is based on an array type, it is allowed to <quote>look
       through</> the domain type to access the array elements, including
       subscripting the domain value to fetch or assign an element.
       Assignment to an element of such a domain value, for instance via
       <literal>UPDATE ... SET domaincol[5] = ...</>, will now result in
       rechecking the domain type's constraints, whereas before the checks
       were skipped.
      </para>

      <para>
       Also, such a domain type is no longer allowed to match an
       <type>anyarray</> parameter of a polymorphic function, except by
       explicitly downcasting it to the base array type.
      </para>
     </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Arrays</title>

    <itemizedlist>

     <listitem>
      <para>
       Change <link
       linkend="array-functions-table"><function>string_to_array()</></link>
       to return an empty array for a zero-length string (Pavel
       Stehule)
      </para>

      <para>
       Previously this returned a null value.
      </para>
     </listitem>

     <listitem>
      <para>
       Change <link
       linkend="array-functions-table"><function>string_to_array()</></link>
       so a <literal>NULL</> separator splits the string into characters
       (Pavel Stehule)
      </para>

      <para>
       Previously this returned a null value.
      </para>
     </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Object Modification</title>

    <itemizedlist>

     <listitem>
      <para>
       Fix improper checks for before/after triggers (Tom Lane)
      </para>

      <para>
       Triggers can now be fired in three cases: <literal>BEFORE</>,
       <literal>AFTER</>, or <literal>INSTEAD OF</> some action.
       Trigger function authors should verify that their logic behaves
       sanely in all three cases.
      </para>
     </listitem>

     <listitem>
      <para>
        Require superuser or <literal>CREATEROLE</> permissions in order to
        set role comments (Tom Lane)
      </para>
     </listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

     <listitem>
      <para>
       Change <link
       linkend="functions-recovery-info-table"><function>pg_last_xlog_receive_location()</></link>
       so it never moves backwards (Fujii Masao)
      </para>

      <para>
       Previously <function>pg_last_xlog_receive_location()</> could
       move backward when streaming replication is restarted.
      </para>
     </listitem>

     <listitem>
      <para>
       Have logging of replication connections honor <link
       linkend="guc-log-connections"><varname>log_connections</></link>
       (Magnus Hagander)
      </para>

      <para>
       Previously replication connections were always logged.
      </para>
     </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title><link linkend="plpgsql">PL/pgSQL</link> Server-Side Language</title>

    <itemizedlist>

     <listitem>
      <para>
       Change PL/pgSQL's <literal>RAISE</> command without parameters
       to be catchable by the attached exception block (Piyush Newe)
      </para>

      <para>
       Previously <literal>RAISE</> in a code block was always scoped to
       an attached exception block, so it was uncatchable at the same
       scope.
      </para>
     </listitem>

     <listitem>
      <para>
       Adjust PL/pgSQL's error line reporting code to be consistent
       with other PLs (Pavel Stehule)
      </para>

      <para>
       Previously, PL/pgSQL would ignore (not count) an empty line at the
       start of the function body.  Since this was inconsistent with all
       other languages, the special case was removed.
      </para>
     </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Other Incompatibilities</title>

    <itemizedlist>

     <listitem>
      <para>
       Have <link
       linkend="monitoring-stats-funcs-table"><function>pg_stat_reset()</></link>
       reset all database-level statistics (Tomas Vondra)
      </para>

      <para>
       Some <structname>pg_stat_database</> counters were not being reset.
      </para>
     </listitem>

     <listitem>
      <para>
        Fix some <link
        linkend="infoschema-triggers"><structname>information_schema.triggers</></link>
        column names to match the new SQL-standard names (Dean Rasheed)
      </para>
     </listitem>

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

    </itemizedlist>

   </sect3>
  </sect2>

  <sect2>
   <title>Changes</title>
    <para>
     Version 9.1 has ...
    </para>

   <sect3>
    <title>Server</title>

    <sect4>
     <title>Performance</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow unlogged tables using the <link
        linkend="SQL-CREATETABLE-description"><literal>UNLOGGED</></link>
        clause in <link linkend="SQL-CREATETABLE"><command>CREATE
        TABLE</></link> (Robert Haas)
       </para>

       <para>
        These tables are optimized for performance but are cleared in
        case of a server crash.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <literal>FULL OUTER JOIN</literal> to be implemented as a
        hash join, and allow either side of a <literal>LEFT OUTER JOIN</>
        or <literal>RIGHT OUTER JOIN</> to be hashed (Tom Lane)
       </para>

       <para>
        Previously <literal>FULL OUTER JOIN</literal> could only be
        implemented as a merge join, and <literal>LEFT OUTER JOIN</literal>
        and <literal>RIGHT OUTER JOIN</literal> could hash only the nullable
        side of the join.  These changes provide additional query optimization
        possibilities.
       </para>
      </listitem>

      <listitem>
       <para>
         Merge duplicate fsync requests on busy systems (Robert Haas,
         Greg Smith)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of <link
        linkend="guc-commit-siblings"><varname>commit_siblings</></link>
        (Greg Smith)
       </para>

       <para>
        This allows the use of <varname>commit_siblings</varname> with
        less overhead.
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce the memory requirement for large ispell dictionaries
        (Pavel Stehule, Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Optimizer</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow inheritance table queries to return meaningfully-sorted
        results (Greg Stark, Hans-Jurgen Schonig, Robert Haas, Tom
        Lane)
       </para>

       <para>
        This allows optimization of <literal>ORDER BY</> and
        <literal>LIMIT</> clauses in inheritance table queries.
       </para>
      </listitem>

      <listitem>
       <para>
         Allow optimizations of <literal>MIN</>/<literal>MAX</> for
         inheritance table queries (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Support hashing array values (Tom Lane)
       </para>

       <para>
        This provides additional query optimization possibilities.
       </para>
      </listitem>

      <listitem>
       <para>
         Improve GIN index scan cost estimation (Teodor Sigaev)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Authentication</title>

     <itemizedlist>

      <listitem>
       <para>
        Support host names and host suffixes
        (e.g. <literal>.example.com</>) in <link
        linkend="auth-pg-hba-conf"><filename>pg_hba.conf</></link>
        (Peter Eisentraut)
       </para>

       <para>
        Previously only host <acronym>IP</> addresses and <acronym>CIDR</>
        values were supported.
       </para>
      </listitem>

      <listitem>
       <para>
        Support the key word <literal>all</> in the host column of <link
        linkend="auth-pg-hba-conf"><filename>pg_hba.conf</></link>
        (Peter Eisentraut)
       </para>

       <para>
        Previously people used <literal>0.0.0.0/0</> or <literal>::/0</>
        for this.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="gssapi-auth"><acronym>GSSAPI</></link>
        to be used to authenticate to servers via <link
        linkend="sspi-auth"><acronym>SSPI</></link> (Christian Ullrich)
       </para>

       <para>
        Specifically this allows Unix-based <acronym>GSSAPI</> clients
        to do <acronym>SSPI</> authentication with Windows servers.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Monitoring</title>

     <itemizedlist>

      <listitem>
       <para>
        Add details to the logging of restartpoints and checkpoints,
        which is controlled by <link
        linkend="guc-log-checkpoints"><varname>log_checkpoints</></link>
        (Fujii Masao, Greg Smith)
       </para>

       <para>
        New details show <acronym>WAL</> file and sync activity.
       </para>
      </listitem>

      <listitem>
       <para>
         Add <link
         linkend="guc-log-file-mode"><varname>log_file_mode</></link>
         which controls the permissions on log files created by the
         logging collector (Martin Pihlak)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Statistical Views</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <structfield>client_hostname</structfield> column to <link
        linkend="monitoring-stats-views-table"><structname>pg_stat_activity</></link>
        (Peter Eisentraut)
       </para>

       <para>
        Previously only the client address was reported.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="monitoring-stats-views-table"><structname>pg_stat_xact_*</></link>
        statistics functions and views (Joel Jacobson)
       </para>

       <para>
        These are like the database-wide statistics counter views, but
        reflect counts for only the current transaction.
       </para>
      </listitem>

      <listitem>
       <para>
         Add time of last reset in database-level and background writer
         statistics views (Tomas Vondra)
       </para>
      </listitem>

      <listitem>
       <para>
         Add columns showing the number of vacuum and analyze operations
         in <link
         linkend="monitoring-stats-views-table"><structname>pg_stat_*_tables</></link>
         views (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <structfield>buffers_backend_fsync</> column to <link
        linkend="monitoring-stats-views-table"><structname>pg_stat_bgwriter</></link>
        (Greg Smith)
       </para>

       <para>
        This new column counts the number of times a backend fsyncs a
        buffer.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow auto-tuning of <link
        linkend="guc-wal-buffers"><varname>wal_buffers</></link> (Greg
        Smith)
       </para>

       <para>
        <varname>wal_buffers</> is now auto-tuned by default based on
        the size of <varname>shared_buffers</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Increase the maximum values for
        <link linkend="guc-deadlock-timeout"><varname>deadlock_timeout</varname></link>,
        <link linkend="guc-log-min-duration-statement"><varname>log_min_duration_statement</varname></link>, and
        <link linkend="guc-log-autovacuum-min-duration"><varname>log_autovacuum_min_duration</varname></link>
        (Peter Eisentraut)
       </para>

       <para>
        The maximum value for each of these parameters was previously
        only about 35 minutes.  Much larger values are now allowed.
       </para>
      </listitem>

      </itemizedlist>

    </sect4>

   </sect3>

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

   <sect4>
    <title>Streaming Replication and Continuous Archiving</title>

    <itemizedlist>

     <listitem>
      <para>
       Allow <link linkend="synchronous-replication">synchronous
       replication</link> (Simon Riggs, Fujii Masao)
      </para>

      <para>
       This allows the primary to wait for a standby to write the transaction
       information to disk before acknowledging the commit.
       One standby at a time can take the role of the synchronous standby,
       as controlled by the
       <link linkend="guc-synchronous-standby-names"><varname>synchronous_standby_names</varname></link>
       setting.  Synchronous replication can be enabled or disabled on a
       per-transaction basis using the
       <link linkend="guc-synchronous-commit"><varname>synchronous_commit</></link>
       setting.
      </para>
     </listitem>

     <listitem>
      <para>
       Add protocol support for sending file system backups to standbys using
       the streaming replication network connection (Magnus Hagander,
       Heikki Linnakangas)
      </para>

      <para>
       This avoids the requirement of manually transferring a file
       system backup when creating a standby server.
      </para>
     </listitem>

     <listitem>
      <para>
       Add command-line tool <link
       linkend="app-pgbasebackup"><application>pg_basebackup</></link>
       for creating a new standby server or database backup (Magnus
       Hagander)
      </para>
     </listitem>

     <listitem>
      <para>
       Add replication <link linkend="SQL-CREATEROLE">permission</link>
       for roles (Magnus Hagander)
      </para>

      <para>
       This is a read-only permission used for streaming replication
       and allows non-superusers to initiate replication connections.
       Previously only superusers could initiate replication
       connections;  superusers have this permission by default.
      </para>
     </listitem>

     <listitem>
      <para>
       <link linkend="auth-ident"><literal>ident</literal></link>
       authentication over local sockets is now known as
       <link linkend="auth-peer"><literal>peer</literal></link>
       (Magnus Hagander)
      </para>

      <para>
       The old term is still accepted for backward compatibility.
      </para>
     </listitem>

    </itemizedlist>

    </sect4>

    <sect4>
     <title>Replication Monitoring</title>

     <itemizedlist>

      <listitem>
       <para>
        Add system view <link
        linkend="monitoring-stats-views-table"><structname>pg_stat_replication</></link>
        which displays activity of <acronym>WAL</> sender processes (Itagaki
        Takahiro, Simon Riggs)
       </para>

       <para>
        This reports the status of all connected standby servers.
       </para>
      </listitem>

      <listitem>
       <para>
        Add monitoring function <link
        linkend="functions-recovery-info-table"><function>pg_last_xact_replay_timestamp()</></link>
        (Fujii Masao)
       </para>

       <para>
        This returns the time on the primary that generated the most
        recent commit or abort record applied on the standby.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Hot Standby</title>

     <itemizedlist>

     <listitem>
      <para>
       Add configuration parameter <link
       linkend="guc-hot-standby-feedback"><varname>hot_standby_feedback</></link>
       to enable standbys to postpone cleanup of old row versions on the
       primary (Simon Riggs)
      </para>

      <para>
       This helps avoid cancelling long-running queries on the standby.
      </para>
     </listitem>

      <listitem>
       <para>
        Add the <link
        linkend="monitoring-stats-views-table"><structname>pg_stat_database_conflicts</></link>
        system view to show queries that have been canceled and the
        reason (Magnus Hagander)
       </para>

       <para>
        Cancellations can occur because of dropped tablespaces, lock
        timeouts, old snapshots, pinned buffers, and deadlocks.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <structfield>conflicts</> count to <link
        linkend="monitoring-stats-views-table"><structname>pg_stat_database</></link>
        (Magnus Hagander)
       </para>

       <para>
        This is the number of conflicts that occurred in the database.
       </para>
      </listitem>

      <listitem>
       <para>
        Increase the maximum values for
        <link linkend="guc-max-standby-archive-delay"><varname>max_standby_archive_delay</varname></link> and
        <link linkend="guc-max-standby-streaming-delay"><varname>max_standby_streaming_delay</varname></link>.
       </para>

       <para>
        The maximum value for each of these parameters was previously
        only about 35 minutes.  Much larger values are now allowed.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="errcodes-table"><literal>ERRCODE_T_R_DATABASE_DROPPED</></link>
        error code to report recovery conflicts due to dropped databases
        (Tatsuo Ishii)
       </para>

       <para>
        This is useful for connection pooling software.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Recovery Control</title>

     <itemizedlist>

      <listitem>
       <para>
        Add functions to control streaming replication replay (Simon
        Riggs)
       </para>

       <para>
        The new functions are <link
        linkend="functions-recovery-control-table"><function>pg_xlog_replay_pause()</></link>,
        <link
        linkend="functions-recovery-control-table"><function>pg_xlog_replay_resume()</></link>,
        and the status function <link
        linkend="functions-recovery-control-table"><function>pg_is_xlog_replay_paused()</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <filename>recovery.conf</> setting <link
        linkend="pause-at-recovery-target"><varname>pause_at_recovery_target</></link>
        to pause recovery at target (Simon Riggs)
       </para>

       <para>
        This allows a recovery server to be queried to check whether
        the recovery point is the one desired.
       </para>
      </listitem>

      <listitem>
       <para>
        Add the ability to create named restore points using <link
        linkend="functions-admin-backup-table"><function>pg_create_restore_point()</></link>
        (Jaime Casanova)
       </para>

       <para>
        These named restore points can be specified as recovery
        targets using the new <filename>recovery.conf</> setting
        <link linkend="recovery-target-name"><varname>recovery_target_name</></link>
       </para>
      </listitem>

      <listitem>
       <para>
        Allow standby recovery to switch to a new timeline automatically
        (Heikki Linnakangas)
       </para>

       <para>
        Now standby servers scan the archive directory for new
        timelines periodically.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="guc-restart-after-crash"><varname>restart_after_crash</></link>
        which disables server restart after a backend crash (Robert
        Haas)
       </para>

       <para>
        This allows external cluster management software to take control
        of whether servers restart or not.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link
        linkend="recovery-config"><filename>recovery.conf</></link>
        to use the same quoting behavior as <filename>postgresql.conf</>
        (Dimitri Fontaine)
       </para>

       <para>
        Previously all values had to be quoted.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Queries</title>

     <itemizedlist>

      <listitem>
       <para>
        Add a true <link
        linkend="xact-serializable">serializable</link> isolation
        level (Kevin Grittner, Dan Ports)
       </para>

       <para>
        Previously, asking for serializable isolation guaranteed only that a
        single MVCC snapshot would be used for the entire transaction, which
        allowed certain documented anomalies.  The old snapshot isolation
        behavior is still accessible by requesting the <link
        linkend="xact-repeatable-read"><literal>REPEATABLE READ</></link>
        isolation level.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow data-modification commands
        (<command>INSERT</>/<command>UPDATE</>/<command>DELETE)</> in
        <link linkend="queries-with"><literal>WITH</></link> clauses
        (Marko Tiikkaja, Hitoshi Harada)
       </para>

       <para>
        These commands can use <literal>RETURNING</> to pass data up to the
        containing query.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="queries-with"><literal>WITH</></link>
        clauses to be attached to <command>INSERT</>, <command>UPDATE</>,
        <command>DELETE</> statements (Marko Tiikkaja, Hitoshi Harada)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow non-<link linkend="queries-group"><literal>GROUP
        BY</></link> columns in the query target list when the primary
        key is specified in the <literal>GROUP BY</> clause (Peter
        Eisentraut)
       </para>

       <para>
        Some other database system already allowed this behavior, and
        because of the primary key, the result is unambiguous.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow use of the key word <literal>DISTINCT</> in <link
        linkend="queries-union"><literal>UNION</>/<literal>INTERSECT</>/<literal>EXCEPT</></link>
        clauses (Tom Lane)
       </para>

       <para>
        <literal>DISTINCT</> is the default behavior so use of this
        key word is redundant, but the SQL standard allows it.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix ordinary queries with rules to use the same snapshot behavior
        as <command>EXPLAIN ANALYZE</> (Marko Tiikkaja)
       </para>

       <para>
        Previously <command>EXPLAIN ANALYZE</> used a slightly different
        snapshot for queries involving rules.  The <command>EXPLAIN ANALYZE</>
        behavior was judged to be more logical.
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title>Strings</title>

     <itemizedlist>

      <listitem>
       <para>
        Add per-column <link
        linkend="collation">collation</link> support
        (Peter Eisentraut, Tom Lane)
       </para>

       <para>
        Previously collation could only be set at database creation.
        Collation can now be set per column, domain, index, or
        expression, via the SQL-standard <literal>COLLATE</> clause.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Add support for <link linkend="SQL-CREATEFOREIGNTABLE">foreign
        tables</link> (Shigeru Hanada, Robert Haas, Jan Urbanski,
        Heikki Linnakangas)
       </para>

       <para>
        This allows data stored outside the database to be used like
        native <productname>PostgreSQL</>-stored data.  Foreign tables
        are currently read-only, however.
       </para>
      </listitem>

     <listitem>
      <para>
         Allow new values to be added to an existing enum type via
         <link linkend="SQL-ALTERTYPE"><command>ALTER TYPE</></link> (Andrew
         Dunstan)
      </para>
     </listitem>

      <listitem>
       <para>
        Add <link linkend="SQL-ALTERTYPE"><command>ALTER TYPE ...
        ADD/DROP/ALTER/RENAME ATTRIBUTE</></link> (Peter Eisentraut)
       </para>

       <para>
        This allows modification of composite types.
       </para>
      </listitem>

     </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Add <literal>RESTRICT</>/<literal>CASCADE</> to <link
        linkend="SQL-ALTERTYPE"><command>ALTER TYPE</></link> operations
        on typed tables (Peter Eisentraut)
       </para>

       <para>
        This controls
        <literal>ADD</>/<literal>DROP</>/<literal>ALTER</>/<literal>RENAME
        ATTRIBUTE</> cascading behavior.
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for more object types in <command>ALTER ... SET
        SCHEMA</> commands (Dimitri Fontaine)
       </para>

       <para>
        This command is now supported for conversions, operators, operator
        classes, operator families, text search configurations, and text search
        dictionaries, text search parsers, and text search templates.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="SQL-CREATETABLE"><command>CREATE/ALTER TABLE</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <command>ALTER TABLE ...
        ADD UNIQUE/PRIMARY KEY USING INDEX</command>
        (Gurjeet Singh)
       </para>

       <para>
        This allows a primary key or unique constraint to be added using an
        existing unique index, including a concurrently created unique index.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <command>ALTER TABLE</>
        to add foreign keys without validation (Simon Riggs)
       </para>

       <para>
        The new option is called <literal>NOT VALID</>, which can
        later be modified to <literal>VALIDATED</> and validation
        checks performed. Together these allow you to add a foreign key
        with minimal impact on read and write operations.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="SQL-ALTERTABLE"><command>ALTER TABLE
        ... SET DATA TYPE</command></link> to avoid table rewrites in
        appropriate cases (Noah Misch, Robert Haas)
       </para>

       <para>
        For example, converting a <type>varchar</> column to
        <type>text</> no longer requires a rewrite of the table.
        However, increasing the length constraint on a
        <type>varchar</> column still requires a table rewrite.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="SQL-CREATETABLE"><command>CREATE TABLE IF
        NOT EXISTS</></link> syntax (Robert Haas)
       </para>

       <para>
        This allows table creation without causing an error if the
        table already exists.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix possible <quote>tuple concurrently updated</quote> error
        when two server backends attempted to add an inheritance
        parent to the same table at the same time (Robert Haas)
       </para>

       <para>
        <link linkend="sql-altertable"><command>ALTER TABLE</command></link>
        now takes a stronger lock on the parent table, so that both children do
        not try to update it simultaneously.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Object Permissions</title>

     <itemizedlist>

      <listitem>
       <para>
        Add a <link linkend="SQL-SECURITY-LABEL"><command>SECURITY
        LABEL</></link> command (KaiGai Kohei)
       </para>

       <para>
        This allows security labels to be assigned to objects.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Utility Operations</title>

    <itemizedlist>

     <listitem>
      <para>
       Add transaction-level <link linkend="advisory-locks">advisory
       locks</link> (Marko Tiikkaja)
      </para>

      <para>
       This is similar to the existing session-level advisory locks,
       but the locks are automatically released at transaction end.
      </para>
     </listitem>

     <listitem>
      <para>
       Make <link linkend="SQL-TRUNCATE"><command>TRUNCATE ... RESTART
       IDENTITY</></link> restart sequences transactionally (Steve
       Singer)
      </para>

      <para>
       Previously the counter could have been left out of sync if a
       backend crashed between the on-commit truncation activity and
       commit completion.
      </para>
     </listitem>

    </itemizedlist>

    <sect4>
     <title><link linkend="SQL-COPY"><command>COPY</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <literal>ENCODING</> option to <link
        linkend="SQL-COPY"><command>COPY TO/FROM</></link> (Hitoshi
        Harada, Itagaki Takahiro)
       </para>

       <para>
        This allows the encoding of the <command>COPY</> file to be
        specified separately from client encoding.
       </para>
      </listitem>

      <listitem>
       <para>
        Add bidirectional <link linkend="SQL-COPY"><command>COPY</></link>
        protocol support (Fujii Masao)
       </para>

       <para>
        This is currently only used by streaming replication.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="SQL-EXPLAIN"><command>EXPLAIN</></link></title>

      <itemizedlist>

      <listitem>
       <para>
        Make <command>EXPLAIN VERBOSE</> show the function call expression
        in a <literal>FunctionScan</literal> node (Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="SQL-VACUUM"><command>VACUUM</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add additional details to the output of <link
        linkend="SQL-VACUUM"><command>VACUUM FULL VERBOSE</></link>
        and <link linkend="SQL-CLUSTER"><command>CLUSTER VERBOSE</></link>
        (Itagaki Takahiro)
       </para>

       <para>
        New information includes the live and dead tuple count and
        whether <command>CLUSTER</> is using an index to rebuild.
       </para>
      </listitem>

      <listitem>
       <para>
        Prevent <link linkend="autovacuum">autovacuum</link> from
        waiting if it cannot acquire a lock (Robert Haas)
       </para>

       <para>
        It will try to vacuum later.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="SQL-CLUSTER"><command>CLUSTER</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Allow <command>CLUSTER</> to sort the table rather than scanning
        the index when it seems likely to be cheaper (Leonardo Francalanci)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Indexes</title>

     <itemizedlist>

      <listitem>
       <para>
        Add nearest-neighbor (order-by-operator) searching to <link
        linkend="GiST"><acronym>GiST</> indexes</link> (Teodor Sigaev, Tom Lane)
       </para>

       <para>
        This allows <acronym>GiST</> indexes to quickly return the
        <replaceable>N</> closest values in a query with <literal>LIMIT</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="GIN"><acronym>GIN</> indexes</link> to index null
        and empty values (Tom Lane)
       </para>

       <para>
        This allows full <acronym>GIN</> index scans, and fixes various
        corner cases in which GIN scans would fail.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="GIN"><acronym>GIN</> indexes</link> to
        better recognize duplicate search entries (Tom Lane)
       </para>

       <para>
        This reduces the cost of index scans, especially in cases where
        it avoids unnecessary full index scans.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <link linkend="GiST"><acronym>GiST</> indexes</link> to be fully
        crash-safe (Heikki Linnakangas)
       </para>

       <para>
        Previously there were rare cases where a <command>REINDEX</>
        would be required (you would be informed).
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

     <listitem>
      <para>
       Allow <type>numeric</> to use a more compact, two-byte header
       in many cases (Robert Haas)
      </para>

      <para>
       Previously all <type>numeric</> values had four-byte headers;
       this saves on disk storage.
      </para>
     </listitem>

     <listitem>
      <para>
        Add support for dividing <type>money</> by <type>money</>
        (Andy Balholm)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow binary I/O on type <type>void</type> (Radoslaw Smogura)
      </para>
     </listitem>

     <listitem>
      <para>
       Improve hypotenuse calculations for geometric operators (Paul Matthews)
      </para>

      <para>
       This avoids unnecessary overflows, and may also be more accurate.
      </para>
     </listitem>

    </itemizedlist>

    <sect4>
     <title>Casting</title>

     <itemizedlist>

     <listitem>
      <para>
        Add support for casting between <type>money</> and <type>numeric</>
        (Andy Balholm)
      </para>
     </listitem>

      <listitem>
       <para>
        Allow casting a table's row type to the table's supertype if
        it's a typed table (Peter Eisentraut)
       </para>

       <para>
        This is analogous to the existing facility that allows casting a row
        type to a supertable's row type.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="functions-xml"><acronym>XML</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <acronym>XML</> function <link
        linkend="xml-exists"><literal>XMLEXISTS</></link> and <link
        linkend="xml-exists"><function>xpath_exists()</></link>
        functions (Mike Fowler)
       </para>

       <para>
        These are used for XPath matching.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>XML</> functions <link
        linkend="xml-is-well-formed"><function>xml_is_well_formed()</></link>,
        <link
        linkend="xml-is-well-formed"><function>xml_is_well_formed_document()</></link>,
        <link
        linkend="xml-is-well-formed"><function>xml_is_well_formed_content()</></link>
        (Mike Fowler)
       </para>

       <para>
        These check whether the input is properly-formed <acronym>XML</>.
        They provide functionality that was previously available only in
        the deprecated <filename>contrib/xml2</filename> module.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Add SQL function <link
        linkend="format"><function>format(text)</></link>, which
        behaves like C's <function>printf()</> (Pavel Stehule, Robert
        Haas)
       </para>

       <para>
        It currently supports formats for strings, SQL literals, and
        SQL identifiers.
       </para>
      </listitem>

      <listitem>
       <para>
        Add string functions <link
        linkend="functions-string-other"><function>concat()</></link>,
        <link
        linkend="functions-string-other"><function>concat_ws()</></link>,
        <link linkend="functions-string-other"><function>left()</></link>,
        <link linkend="functions-string-other"><function>right()</></link>,
        and <link
        linkend="functions-string-other"><function>reverse()</></link>
        (Pavel Stehule)
       </para>

       <para>
        These improve compatibility with other database products.
       </para>
      </listitem>

      <listitem>
       <para>
         Add function <link
         linkend="functions-admin-genfile"><function>pg_read_binary_file()</></link>
         to read binary files (Dimitri Fontaine, Itagaki Takahiro)
       </para>
      </listitem>

      <listitem>
       <para>
         Add a single-parameter version of function <link
         linkend="functions-admin-genfile"><function>pg_read_file()</></link>
         to read an entire file (Dimitri Fontaine, Itagaki Takahiro)
       </para>
      </listitem>

      <listitem>
       <para>
         Add three-parameter forms of <link
         linkend="array-functions-table"><function>array_to_string()</></link>
         and <link
         linkend="array-functions-table"><function>string_to_array()</></link>
         for null value processing control (Pavel Stehule)
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title>Object Information Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Add the <link
        linkend="functions-info-catalog-table"><function>pg_describe_object()</></link>
        function (Alvaro Herrera)
       </para>

       <para>
        This function is used to obtain a human-readable string describing an
        object, based on the <link linkend="catalog-pg-class"><structname>pg_class</structname></link> OID, object OID, and sub-object OID.  It can be used to
        help interpret the contents of <link linkend="catalog-pg-depend"><structname>pg_depend</structname></link>.
       </para>
      </listitem>

      <listitem>
       <para>
         Update comments for built-in operators and their underlying
         functions (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add variable <link
        linkend="guc-quote-all-identifiers"><varname>quote_all_identifiers</></link>
        to force the quoting of all identifiers in <command>EXPLAIN</>
        and in system catalog functions like <link
        linkend="functions-info-catalog-table"><function>pg_get_viewdef()</></link>
        (Robert Haas)
       </para>

       <para>
        This makes exporting schemas to tools and other databases with
        different quoting rules easier.
       </para>
      </listitem>

      <listitem>
       <para>
        Add columns to the <link
        linkend="infoschema-sequences"><structname>information_schema.sequences</></link>
        system view (Peter Eisentraut)
       </para>

       <para>
        Previously, though the view existed, the columns about the
        sequence parameters were unimplemented.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <literal>public</> as a pseudo-role name in <link
        linkend="functions-info-access-table"><function>has_table_privilege()</></link>
        and related functions (Alvaro Herrera)
       </para>

       <para>
        This allows checking for public permissions.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Function and Trigger Creation</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow <link linkend="SQL-CREATETRIGGER"><literal>INSTEAD
        OF</></link> triggers on views (Dean Rasheed)
       </para>

       <para>
        This feature can be used to implement fully updatable views.
       </para>
      </listitem>

      <listitem>
       <para>
        Minimize lock levels for <link
        linkend="SQL-CREATETRIGGER"><command>CREATE TRIGGER</></link>
        and many <link linkend="SQL-ALTERTABLE"><command>ALTER
        TABLE</></link> and <link linkend="SQL-CREATERULE"><command>CREATE
        RULE</></link> operations (Simon Riggs)
       </para>

       <para>
        This improves database availability when altering active databases.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

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

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="plpgsql-foreach-array"><command>FOREACH IN
        ARRAY</></link> to <link linkend="plpgsql">PL/pgSQL</link>
        (Pavel Stehule)
       </para>

       <para>
        This is more efficient and readable than previous methods of
        iterating through the elements of an array value.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <command>RAISE</command> without parameters to be caught in
        the same places that could catch a <command>RAISE ERROR</command>
        from the same location (Piyush Newe)
       </para>

       <para>
        The previous coding threw the error
        from the block containing the active exception handler.
        The new behavior is more consistent with other DBMS products.
       </para>
      </listitem>

    </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="plperl">PL/Perl</link> Server-Side Language</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow generic record arguments to PL/Perl functions (Andrew
        Dunstan)
       </para>

       <para>
        PL/Perl functions can now be declared to accept type <type>record</>.
        The behavior is the same as for any named composite type.
       </para>
      </listitem>

      <listitem>
       <para>
        Convert PL/Perl array arguments to Perl arrays (Alexey Klyukin,
        Alex Hunsaker)
       </para>

       <para>
        String representations are still available.
       </para>
      </listitem>

      <listitem>
       <para>
        Convert PL/Perl composite-type arguments to Perl hashes
        (Alexey Klyukin, Alex Hunsaker)
       </para>

       <para>
        String representations are still available.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Add table function support for PL/Python (Jan Urbanski)
       </para>

       <para>
        PL/Python can now return multiple <literal>OUT</> parameters
        and record sets.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a validator to PL/Python (Jan Urbanski)
       </para>

       <para>
        This allows PL/Python functions to be syntax-checked at function
        creation time.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow exceptions for SQL queries in PL/Python (Jan Urbanski)
       </para>

       <para>
        This allows access to SQL-generated exception error codes from
        PL/Python exception blocks.
       </para>
      </listitem>

      <listitem>
       <para>
         Add PL/Python explicit subtransactions (Jan Urbanski)
       </para>
      </listitem>

      <listitem>
       <para>
        Add PL/Python functions for quoting strings (Jan Urbanski)
       </para>

       <para>
        The functions are <link
        linkend="plpython-util"><literal>plpy.quote_ident</></link>,
        <link linkend="plpython-util"><literal>plpy.quote_literal</></link>,
        and <link
        linkend="plpython-util"><literal>plpy.quote_nullable</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
         Report PL/Python errors from iterators with <literal>PLy_elog</> (Jan
         Urbanski)
       </para>
      </listitem>

      <listitem>
       <para>
        Fix exception handling with Python 3 (Jan Urbanski)
       </para>

       <para>
        Exception classes were previously not available in
        <literal>plpy</> under Python 3.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

     <listitem>
      <para>
        Mark <link
        linkend="APP-CREATELANG"><application>createlang</></link>
        and <link linkend="APP-DROPLANG"><application>droplang</></link>
        as deprecated now that they just invoke extension commands (Tom
        Lane)
      </para>
     </listitem>

    </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
         Add the <literal>\conninfo</> command to <application>psql</>,
         to show current connection information (David Christensen)
       </para>
      </listitem>

      <listitem>
       <para>
         Add <application>psql</> command <literal>\sf</> to
         show a function's definition (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
         Add <application>psql</> command <literal>\dL</> to list
         languages (Fernando Ike)
       </para>
      </listitem>

      <listitem>
       <para>
        Add system table <option>S</> option to <application>psql</>
        <literal>\dn</> (schemas) (Tom Lane)
       </para>

       <para>
        <literal>\dn</> without <literal>S</> now suppresses system
        schemas.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>psql</>'s <literal>\e</> and <literal>\ef</>
        commands to accept a line number to be used to position the
        cursor in the editor (Pavel Stehule)
       </para>

       <para>
        This is passed to the editor using the
        <envar>EDITOR_LINENUMBER_SWITCH</> environment variable.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <application>psql</> set the client encoding from the
        operating system locale by default (Heikki Linnakangas)
       </para>

       <para>
        This only happens if the <envar>PGCLIENTENCODING</> environment
        variable is not set.
       </para>
      </listitem>

      <listitem>
       <para>
        Make <application>psql</application> distinguish between unique
        indexes and unique constraints (Josh Kupershmidt)
       </para>
      </listitem>

      <listitem>
       <para>
        Additional tab completion support (Itagaki Takahiro, Pavel Stehule,
        Andrey Popp, Christoph Berg, David Fetter, Josh Kupershmidt)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
         Add <link linkend="APP-PGDUMP"><application>pg_dump</></link>
         and <link
         linkend="APP-PG-DUMPALL"><application>pg_dumpall</></link>
         option <option>--quote-all-identifiers</> to force quoting
         of all identifiers (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <literal>directory</> format to <application>pg_dump</>
        (Joachim Wieland, Heikki Linnakangas)
       </para>

       <para>
        This is internally similar to the <literal>tar</>
        <application>pg_dump</> format.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="APP-PG-CTL"><application>pg_ctl</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Fix <application>pg_ctl</>
        so it no longer incorrectly reports that the server is not
        running (Bruce Momjian)
       </para>

       <para>
        Previously this could happen if the server was running but
        <application>pg_ctl</> could not authenticate.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <application>pg_ctl</> start's <quote>wait</quote>
        (<option>-w</>) mode to handle non-standard port numbers,
        non-standard Unix-domain socket locations, permission
        problems, and stale postmaster lock files (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
         Add <literal>promote</> option to <application>pg_ctl</> to
         switch a standby server to primary (Fujii Masao)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title><application>Development Tools</></title>

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

     <itemizedlist>

      <listitem>
       <para>
        Add a libpq connection option <literal>client_encoding</>
        which behaves like the <envar>PGCLIENTENCODING</> environment
        variable (Heikki Linnakangas)
       </para>

       <para>
        The value <literal>auto</> sets the client encoding based on
        the operating system locale.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="libpq-pqlibversion"><function>PQlibVersion()</></link>
        function which returns the libpq library version (Magnus
        Hagander)
       </para>

       <para>
        libpq already had <function>PQserverVersion()</> which returns
        the server version.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow libpq database clients to use Unix-domain sockets to
        check the user name of the server process using <link
        linkend="libpq-connect-requirepeer"><literal>requirepeer</></link>
        (Peter Eisentraut)
       </para>

       <para>
        <productname>PostgreSQL</> already allowed servers to determine
        the client user name via Unix-domain sockets.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="libpq-pqping"><function>PQping()</></link>
        and <link
        linkend="libpq-pqpingparams"><function>PQpingParams()</></link>
        to libpq (Bruce Momjian, Tom Lane)
       </para>

       <para>
        The allow detection of the server's status without creating
        a new session.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="ecpg"><application>ECPG</></link></title>

     <itemizedlist>

      <listitem>
       <para>
         Allow ECPG to accept dynamic cursor names even in
         <literal>WHERE CURRENT OF</literal> clauses
       </para>
      </listitem>

     </itemizedlist>
    </sect4>

   </sect3>

   <sect3>
    <title>Build Options</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="extension">extensions</link> which simplify
        packaging of additions to <productname>PostgreSQL</> (Dimitri
        Fontaine, Tom Lane)
       </para>

       <para>
        This is controlled by the new <link
        linkend="SQL-CREATEEXTENSION"><command>CREATE</></link>/<link
        linkend="SQL-ALTEREXTENSION"><command>ALTER</></link>/<link
        linkend="SQL-DROPEXTENSION"><command>DROP EXTENSION </></link>
        command;  this replaces a more manual method of adding features
        to <productname>PostgreSQL</>.
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title>Makefiles</title>

     <itemizedlist>

      <listitem>
       <para>
        Improved parallel make support (Peter Eisentraut)
       </para>

       <para>
        This allows for faster compiles.  Also, <literal>make -k</>
        now works properly.
       </para>
      </listitem>

      <listitem>
       <para>
         Require <acronym>GNU</> <link
         linkend="install-requirements"><application>make</></link>
         3.80 or newer (Peter Eisentraut)
       </para>

       <para>
        This is necessary because of the parallel-make improvements.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Windows</title>

     <itemizedlist>

      <listitem>
       <para>
         On Windows, allow <link
         linkend="app-pg-ctl"><application>pg_ctl</></link> to register
         the service as auto-start or start-on-demand (Quan Zongliang)
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for collecting <link linkend="windows-crash-dumps">crash
        dumps</link> on Windows (Craig Ringer, Magnus Hagander)
       </para>

       <para>
        <productname>minidumps</> can now be generated by non-debug
        Windows binaries and analyzed by standard debugging tools.
       </para>
      </listitem>

      <listitem>
       <para>
        Enable building with the MinGW64 compiler (Andrew Dunstan)
       </para>

       <para>
        This allows building 64-bit Windows binaries even on non-Windows
        platforms with cross-compiling.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
         Add latches to the source code to wait for events (Heikki
         Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
         Centralize data modification permissions-checking logic
         (KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
         Add missing <function>get_<replaceable>object</>_oid()</function> functions, for consistency
         (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
         Improve ability to use C++ compilers for <link
         linkend="xfunc-c">compiling add-on modules</link> by removing
         conflicting key words (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
         Add support for DragonFly <acronym>BSD</> (Rumko)
       </para>
      </listitem>

      <listitem>
       <para>
         Expose <function>quote_literal_cstr()</> for backend use
         (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Run <link linkend="build">regression tests</link> in the
        default encoding (Peter Eisentraut)
       </para>

       <para>
        Regression tests were previously always run with
        <literal>SQL_ASCII</> encoding.
       </para>
      </listitem>

      <listitem>
       <para>
         Add <application>src/tools/git_changelog</> to replace
         <application>cvs2cl</> and <application>pgcvslog</> (Robert
         Haas, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <application>git-external-diff</> script to
        <filename>src/tools</> (Bruce Momjian)
       </para>

       <para>
        This is used to generate context diffs from git.
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title>Server Hooks</title>

     <itemizedlist>

      <listitem>
       <para>
         Add source code hooks to check permissions (Robert Haas,
         Stephen Frost)
       </para>
      </listitem>

      <listitem>
       <para>
         Add post-object-creation function hooks for use by security
         frameworks (KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
         Add a client authentication hook (KaiGai Kohei)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Contrib</title>

    <itemizedlist>

     <listitem>
      <para>
       Modify <filename>contrib</> modules and stored procedure
       languages to install via the new <link
       linkend="extension">extension</link> mechanism (Tom Lane,
       Dimitri Fontaine)
      </para>

      <para>
       This replaces a more manual method of installation.
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link linkend="file-fdw"><filename>contrib/file_fdw</></link>
       foreign-data wrapper (Shigeru Hanada)
      </para>

      <para>
       Foreign tables using this foreign data wrapper can read flat files
       in a manner very similar to <command>COPY</>.
      </para>
     </listitem>

     <listitem>
      <para>
        Add nearest-neighbor support to <link
        linkend="pgtrgm"><filename>contrib/pg_trgm</></link> and <link
        linkend="btree-gist"><filename>contrib/btree_gist</></link>
        (Teodor Sigaev)
      </para>
     </listitem>

     <listitem>
      <para>
        Add <link
        linkend="btree-gist"><filename>contrib/btree_gist</></link>
        support for searching on not-equals (Jeff Davis)
      </para>
     </listitem>

     <listitem>
      <para>
        Allow <link
        linkend="fuzzystrmatch"><filename>contrib/fuzzystrmatch</></link>'s
        <function>levenshtein()</> function handle multibyte characters
        (Alexander Korotkov)
      </para>
     </listitem>

     <listitem>
      <para>
        Add <function>ssl_cipher()</> and <function>ssl_version()</>
        functions to <link
        linkend="sslinfo"><filename>contrib/sslinfo</></link> (Robert
        Haas)
      </para>
     </listitem>

     <listitem>
      <para>
       Fix <link linkend="intarray"><filename>contrib/intarray</></link>
       and <link linkend="hstore"><filename>contrib/hstore</></link>
       to give consistent results with indexed empty arrays (Tom Lane)
      </para>

      <para>
       Previously an empty-array query that used an index might return
       different results from one that used a sequential scan.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <link linkend="intarray"><filename>contrib/intarray</></link>
       to work properly on multidimensional arrays (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       In
       <link linkend="intarray"><filename>contrib/intarray</></link>,
       avoid errors complaining about the presence of nulls in cases where no
       nulls are actually present (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       In
       <link linkend="intarray"><filename>contrib/intarray</></link>,
       fix behavior of containment operators with respect to empty arrays
       (Tom Lane)
      </para>

      <para>
       Empty arrays are now correctly considered to be contained in any other
       array.
      </para>
     </listitem>

     <listitem>
      <para>
       Remove <link linkend="xml2"><filename>contrib/xml2</></link>'s
       arbitrary limit on the number of
       <replaceable>parameter</>=<replaceable>value</> pairs that can be
       handled by <function>xslt_process()</> (Pavel Stehule)
      </para>

      <para>
       The previous limit was 10.
      </para>
     </listitem>

     <listitem>
      <para>
       In <link linkend="pageinspect"><filename>contrib/pageinspect</></link>,
       fix heap_page_item to return infomasks as 32-bit values (Alvaro Herrera)
      </para>

      <para>
       This avoids returning negative values, which was confusing.  The
       underlying value is a 16-bit unsigned integer.
      </para>
     </listitem>

    </itemizedlist>

    <sect4>
     <title>Security</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="sepgsql"><filename>contrib/sepgsql</></link>
        to interface permission checks with <acronym>SE</>-Linux (KaiGai Kohei)
       </para>

       <para>
        This uses the new <link
        linkend="SQL-SECURITY-LABEL"><command>SECURITY LABEL</></link>
        facility.
       </para>
      </listitem>

      <listitem>
       <para>
        Add contrib module <link
        linkend="auth-delay"><filename>auth_delay</></link> (KaiGai
        Kohei)
       </para>

       <para>
        This causes the server to pause before returning authentication
        failure;  it is designed to make brute force password attacks
        more difficult.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="dummy-seclabel">dummy_seclabel</link>
        contrib module (KaiGai Kohei)
       </para>

       <para>
        This is used for permission regression testing.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Performance</title>

     <itemizedlist>

      <listitem>
       <para>
         Add support for <literal>LIKE</> and <literal>ILIKE</> index
         searches to <link
         linkend="pgtrgm"><filename>contrib/pg_trgm</></link> (Alexander
         Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
         Add <function>levenshtein_less_equal()</> function to <link
         linkend="fuzzystrmatch"><filename>contrib/fuzzystrmatch</></link>,
         which is optimized for small distances (Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of index lookups on <link
        linkend="seg"><filename>contrib/seg</></link> columns (Alexander
        Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
         Improve performance of <link
         linkend="pgupgrade"><application>pg_upgrade</></link> for
         databases with many relations (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
         Add flag to <link
         linkend="pgbench"><filename>contrib/pgbench</></link> to
         report per-statement latencies (Florian Pflug)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Fsync Testing</title>

     <itemizedlist>

      <listitem>
       <para>
         Move <filename>src/tools/test_fsync</> to <link
         linkend="pgtestfsync"><filename>contrib/pg_test_fsync</></link>
         (Bruce Momjian, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <literal>O_DIRECT</> support to <link
        linkend="pgtestfsync"><filename>contrib/pg_test_fsync</></link>
        (Bruce Momjian)
       </para>

       <para>
        This matches the use of <literal>O_DIRECT</> by <link
        linkend="guc-wal-sync-method"><varname>wal_sync_method</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
         Add new tests to <link
         linkend="pgtestfsync"><filename>contrib/pg_test_fsync</></link>
         (Bruce Momjian)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Documentation</title>

    <itemizedlist>

     <listitem>
      <para>
        Extensive <link linkend="ecpg"><application>ECPG</> documentation</link>
        improvements (Satoshi Nagayasu)
      </para>
     </listitem>

     <listitem>
      <para>
        Extensive proofreading and documentation improvements
        (Thom Brown, Josh Kupershmidt, Susanne Ebrecht)
      </para>
     </listitem>

     <listitem>
      <para>
       Add documentation for <link
       linkend="guc-exit-on-error"><varname>exit_on_error</></link>
       (Robert Haas)
      </para>

      <para>
       This parameter causes sessions to exit on any error.
      </para>
     </listitem>

     <listitem>
      <para>
       Add documentation for <link
       linkend="functions-info-catalog-table"><function>pg_options_to_table()</></link>
       (Josh Berkus)
      </para>

      <para>
       This parameter shows table storage options.
      </para>
     </listitem>

     <listitem>
      <para>
       Document that it is possible to access all composite type
       fields using <link
       linkend="field-selection"><literal>(compositeval).*</></link>
       syntax (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Document that <link
       linkend="functions-string-other"><function>translate()</></link>
       removes characters in <literal>from</> that don't have a
       corresponding <literal>to</> character (Josh Kupershmidt)
      </para>
     </listitem>

     <listitem>
      <para>
       Merge docs for <command>CREATE CONSTRAINT TRIGGER</> and <link
       linkend="SQL-CREATETRIGGER"><command>CREATE TRIGGER</></link>
       (Alvaro Herrera)
      </para>
     </listitem>

     <listitem>
      <para>
       Centralize <link linkend="ddl-priv">permission</link> and <link
       linkend="upgrading">upgrade</link> documentation (Bruce Momjian)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link linkend="sysvipc-parameters">kernel tuning
       documentation</link> for Solaris 10 (Josh Berkus)
      </para>

      <para>
       Previously only Solaris 9 kernel tuning was documented.
      </para>
     </listitem>

    </itemizedlist>

   </sect3>

  </sect2>
 </sect1>
