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 <sect1 id="release-9-4">
  <title>Release 9.4</title>

  <note>
   <title>Release Date</title>
   <simpara>2014-??-??</simpara>
   <simpara>Current as of 2014-05-10</simpara>
  </note>

  <sect2>
   <title>Overview</title>

   <para>
    Major enhancements in <productname>PostgreSQL</> 9.4 include:
   </para>

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

   <itemizedlist>

     <listitem>
      <para>
       Allow materialized views to be refreshed without blocking reads
      </para>
     </listitem>

     <listitem>
      <para>
       <link linkend="logicaldecoding">Logical decoding</link> allows database
       changes to be streamed out in customizable format
      </para>
     </listitem>

     <listitem>
      <para>
        Allow <link linkend="bgworker">background workers</link>
        to be dynamically registered, started and terminated
      </para>
     </listitem>

     <listitem>
      <para>
       Add structured (non-text) data type (<link
       linkend="datatype-json"><type>JSONB</></link>) for storing
       <type>JSON</> data
      </para>
     </listitem>

     <listitem>
      <para>
       Add <acronym>SQL</>-level command <link
       linkend="SQL-ALTERSYSTEM"><command>ALTER SYSTEM</></link>
       to edit the <filename>postgresql.conf</> configuration file
      </para>
     </listitem>

   </itemizedlist>

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

  </sect2>

  <sect2>

  <title>Migration to Version 9.4</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 9.4 contains a number of changes that may affect compatibility
    with previous releases.  Observe the following incompatibilities:
   </para>

   <itemizedlist>

    <listitem>
     <para>
      Cause consecutive whitespace in <link
      linkend="functions-formatting-table"><function>to_timestamp()</></link>
      and <function>to_date()</> format strings to consume a corresponding
      number of characters in the input string (whitespace or not), then
      conditionally additional adjacent whitespace if not in <literal>FX</>
      mode (Jeevan Chalke)
     </para>

     <para>
      Previously consecutive whitespace characters in a non-<literal>FX</>
      format string behaved like a single whitespace character and consumed
      all adjacent whitespace in the input string.  For example, previously
      format string space-space-space would consume only the first space in
      ' 12', while it will not consume all three characters.
     </para>
    </listitem>

    <listitem>
     <para>
      Tighten checks for multi-dimensional <link
      linkend="arrays">array</link> input (Bruce Momjian)
     </para>

     <para>
      Previously an input array string that started with a single-element
      array dimension could later contain multi-dimensional segments,
      e.g. <literal>'{{1}, {2,3}}'::int[]</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Change empty arrays returned by <application>intarray</> to be
      zero-dimensional arrays (Bruce Momjian)
     </para>

     <para>
      Previously empty arrays were returned as one-dimensional empty arrays
      whose text representation looked the same as zero-dimensional arrays
      (<literal>{}</>).  <application>intarray</>'s behavior in this area
      now matches the built-in array operators.
     </para>
    </listitem>

    <listitem>
     <para>
      NULL <link
      linkend="xfunc-sql-variadic-functions"><literal>VARIADIC</></link>
      function arguments are now disallowed (Pavel Stehule)
     </para>

     <para>
      Such arguments must be cast to an array data type.
     </para>
    </listitem>

    <listitem>
     <para>
      <link linkend="SQL-SHOW"><command>SHOW TIME ZONE</></link> now
      outputs constant time zone offsets in <acronym>POSIX</>-style zone
      format (Tom Lane)
     </para>

     <para>
      Previously it was returned in <link
      linkend="datatype-interval-output"><type>INTERVAL</></link> format.
      The new format can be passed to <command>SET TIME ZONE</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Rename <link linkend="SQL-EXPLAIN"><command>EXPLAIN
      ANALYZE</></link>'s "total runtime" output to "execution time"
      (Tom Lane)
     </para>

     <para>
      This was required now that planning time is also reported.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <link
      linkend="textsearch-functions-table"><function>ts_rank_cd()</></link>
      to ignore stripped lexemes (Alex Hill)
     </para>

     <para>
      Previously stripped lexemes got a default location and could be
      considered if mixed with non-stripped lexemes.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent <link
      linkend="ddl-constraints-check-constraints"><literal>CHECK</></link>
      constraints from referencing system columns, except
      <structfield>tableoid</> (Amit Kapila)
     </para>

     <para>
      Restoring such check constraints will lead to restore errors.
     </para>
    </listitem>

    <listitem>
     <para>
      Use the last specified <link
      linkend="recovery-target"><varname>recovery_target</></link> if
      multiple are specified (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      On Windows, automatically preserve quotes in command strings supplied
      by the user (Heikki Linnakangas)
     </para>

     <para>
      User commands that did their own quote preservation might need
      adjustment, e.g.  <link
      linkend="guc-archive-command">archive_command</link>, <link
      linkend="restore-command">restore_command</link>, <command>COPY TO/FROM
      PROGRAM</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Remove system column <link
      linkend="catalog-pg-class"><structfield>pg_class.reltoastidxid</></link>
      (Michael Paquier)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove support for native <application>krb5</> authentication
      (Magnus Hagander)
     </para>

     <para>
      The proper way to use <application>Kerberos</> authentication is
      with <acronym>GSSAPI</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Handle domains over arrays like plain arrays in PL/Python
      (Rodolfo Campero)
     </para>

     <para>
      Previously they were treated as strings.
     </para>
    </listitem>

    <listitem>
     <para>
      Have libpq's <link
      linkend="libpq-pqconnectdbparams"><function>PQconnectdbParams()</></link>
      and <link
      linkend="libpq-pqpingparams"><function>PQpingParams()</></link>
      functions process zero-length strings as defaults (Adrian
      Vondendriesch)
     </para>

     <para>
      Previously, these functions treated zero-length string values as
      defaults only in some cases.
     </para>
    </listitem>

    <listitem>
     <para>
      Remove system column <link
      linkend="catalog-pg-rewrite"><structfield>pg_rewrite.ev_attr</></link>
      (Kevin Grittner)
     </para>

     <para>
      Per-column rules have not been supported since
      <application>PostgreSQL</> 7.3.
     </para>
    </listitem>

    <listitem>
     <para>
      <link linkend="pgupgrade"><application>Pg_upgrade</></link> now
      uses <option>-U</> to specify the user name (Bruce Momjian)
     </para>

     <para>
      Previously <option>-u</> was used to specify the user name.
      Also spell the long option as <option>--username</>, again for
      consistency with other tools.
     </para>
    </listitem>

    <listitem>
     <para>
      The maximum number of <link linkend="bgworker">background workers</link>
      that can be registered
      by <function>RegisterBackgroundWorker()</function> is now limited to
      <link linkend="guc-max-worker-processes"><varname>max_worker_processes</></link>
     </para>
    </listitem>

   </itemizedlist>

  </sect2>

  <sect2>
   <title>Changes</title>

   <para>
    Below you will find a detailed account of the changes between
    <productname>PostgreSQL</productname> 9.4 and the previous major
    release.
   </para>

   <sect3>
    <title>Server</title>

     <itemizedlist>

      <listitem>
       <para>
        Have <link linkend="SQL-VACUUM"><command>VACUUM</></link> properly
        report dead but not removable rows to the statistics collector
        (Hari Babu)
       </para>

       <para>
        Previously these were reported as live rows.
       </para>
      </listitem>
      <listitem>
       <para>
        Allow <link linkend="bgworker">background workers</link> to be
        dynamically registered, started and terminated (Robert Haas)
       </para>

       <para>
        <function>worker_spi_launch()</> in <application>worker_spi</>
        shows an example of its use.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow dynamic allocation of shared memory segments (Robert Haas,
        Amit Kapila)
       </para>

       <para>
        This is illustrated in <link
        linkend="test-shm-mq"><application>test_shm_mq</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <acronym>SSL</> renegotiation handling (&Aacute;lvaro
        Herrera)
       </para>
      </listitem>

      <listitem>
       <para>
        During immediate shutdown, send uncatchable termination signals
        to child processes that have not already shutdown (MauMau,
        &Aacute;lvaro Herrera)
       </para>

       <para>
        This reduces the likelihood of orphaned child processes after
        <link linkend="app-postmaster"><application>postmaster</></link>
        shutdown.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve randomness of the database system identifier (Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title>Indexes</title>

     <itemizedlist>

      <listitem>
       <para>
        Improve speed of multi-key <link
        linkend="GIN"><acronym>GIN</></link> lookups (Alexander Korotkov,
        Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce <link linkend="GIN"><acronym>GIN</></link> index size
        (Alexander Korotkov, Heikki Linnakangas)
       </para>

       <para>
        Indexes upgraded via <link
        linkend="pgupgrade"><application>pg_upgrade</></link> will work
        fine but will use the old larger <acronym>GIN</> format; <link
        linkend="SQL-REINDEX"><command>REINDEX</></link> will recreate
        the index in the new format.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="GiST"><acronym>GiST</></link> index support
        for <link linkend="datatype-inet"><type>INET</></link> and
        <link linkend="datatype-cidr"><type>CIDR</></link> data types
        (Emre Hasegeli)
       </para>

       <para>
        Such indexes improve <link
        linkend="cidr-inet-operators-table">subnet</link> and supernet
        lookups and ordering comparisons.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix race condition in B-tree page deletion (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Make the handling of interrupted B-tree page splits more robust
        (Heikki Linnakangas)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow multiple backends to simultaneously insert into <link
        linkend="wal"><acronym>WAL</></link> buffers (Heikki Linnakangas)
       </para>

       <para>
        This improves parallel write performance.
       </para>
      </listitem>

      <listitem>
       <para>
        Conditionally write only the modified portion of updated rows to
        <link linkend="wal"><acronym>WAL</></link> (Amit Kapila)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of <link
        linkend="syntax-window-functions"><literal>WINDOW</></link>
        aggregate functions (David Rowley, Florian Pflug, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve speed of aggregates which use <link
        linkend="datatype-numeric"><type>NUMERIC</></link>s (Hadi
        Moshayedi)
       </para>

       <para>
        These include <function>SUM()</>, <function>AVG()</>, <link
        linkend="functions-aggregate-statistics-table"><function>STDDEV()</></link>,
        and <function>VARIANCE()</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Attempt to <link linkend="vacuum-for-wraparound">freeze</link>
        tuples when tables are rewritten with <link
        linkend="SQL-CLUSTER"><command>CLUSTER</></link> or <link
        linkend="SQL-VACUUM"><command>VACUUM FULL</></link> (Robert Haas,
        Andres Freund)
       </para>

       <para>
        This can avoid the need to freeze the tuples in the future.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve speed of <link linkend="SQL-COPY"><command>COPY</></link>
        with <literal>DEFAULT</> <link
        linkend="functions-sequence-table"><function>nextval()</></link>
        columns (Simon Riggs)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve speed of accesessing many different <link
        linkend="SQL-CREATESEQUENCE">sequences</link> in the same session
        (David Rowley)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow sorting and B-tree <link linkend="SQL-CREATEINDEX">index
        builds</link> to use over four gigabytes of memory (Noah Misch)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce memory allocated by <link
        linkend="SQL-DO"><literal>DO</></link> blocks (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Have the optimizer be more aggressive in creating restrictions
        from mixed <literal>AND</>/<literal>OR</> clauses (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Auto-resize the catalog cache (Heikki Linnakangas)
       </para>

       <para>
        This reduces memory consumption for backends accessing only a few
        tables, and improves performance for backend accessing many tables.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Monitoring</title>

     <itemizedlist>

      <listitem>
       <para>
        Expose the estimation of number of changed tuples since last <link
        linkend="vacuum-for-statistics">analyze</link> (Mark Kirkwood)
       </para>

       <para>
        This appears in <link
        linkend="pg-stat-all-tables-view"><structfield>pg_stat_all_tables.n_mod_since_analyze</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="pg-stat-archiver-view"><structname>pg_stat_archiver</></link>
        system view to report <link linkend="wal"><acronym>WAL</></link>
        archiver activity (Gabriele Bartolini)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <varname>backend_xid</> and <varname>backend_xmin</> columns to
        the system view <link linkend="pg-stat-activity-view"><structname>pg_stat_activity</></link>
        and <varname>backend_xmin</> to <link linkend="pg-stat-replication-view"><structname>pg_stat_replication</></link>
        (Christian Kruse)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><acronym>SSL</></title>

     <itemizedlist>

      <listitem>
       <para>
        Add support for <acronym>SSL</> <acronym>ECDH</> key exchange
        (Marko Kreen)
       </para>

       <para>
        Such keys are faster and have improved security over previous
        options. The new configuration
        parameter <link linkend="guc-ssl-ecdh-curve"><varname>ssl_ecdh_curve</></link>
        controls which curve is used.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve the default <link
        linkend="guc-ssl-ciphers"><varname>ssl_ciphers</></link> ciphers
        (Marko Kreen)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow the server to specify the preferred <acronym>SSL</> cipher
        order (Marko Kreen)
       </para>

       <para>
        This is controlled by the new configuration parameter <link
        linkend="guc-ssl-prefer-server-ciphers"><varname>ssl_prefer_server_ciphers</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link
        linkend="guc-log-connections"><varname>log_connections</></link>
        show <acronym>SSL</> encryption information (Andreas Kunert)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Add <acronym>SQL</>-level <link
        linkend="SQL-ALTERSYSTEM"><command>ALTER SYSTEM</></link> command
        to adjust server-wide settings (Amit Kapila)
       </para>

       <para>
        Previously such settings could only be changed by
        editing <filename>postgresql.conf</> at the file system level.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="guc-huge-pages"><varname>huge_pages</></link>
        configuration parameter to use huge memory pages on Linux
        (Christian Kruse, Richard Poole, Abhijit Menon-Sen)
       </para>

       <para>
        This can improve performance on large memory systems.
       </para>
      </listitem>

      <listitem>
       <para>
        Show <acronym>PID</>s of lock holders and
        waiters and improve relation information in <link
        linkend="guc-log-lock-waits"><varname>log_lock_waits</></link>
        log messages (Christian Kruse)
       </para>
      </listitem>

      <listitem>
       <para>
        Add parameter <link
        linkend="guc-autovacuum-work-mem"><varname>autovacuum_work_mem</></link>
        to control the amount of memory used by autovacuum workers
        (Peter Geoghegan)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="guc-max-worker-processes"><varname>max_worker_processes</></link>
        to limit the number of background workers (Robert Haas)
       </para>

       <para>
        This is helpful in configuring the standby server to have the
        required same number of worker processes as the primary.
       </para>
      </listitem>

      <listitem>
       <para>
        Add configuration parameter <link
        linkend="guc-wal-log-hints"><varname>wal_log_hints</></link>
        to enable logging of hint bits (Sawada Masahiko)
       </para>

       <para>
        Hint bits are not normally logged, except when checksums are enabled.
        This is useful for external tools like <application>pg_rewind</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow printf-style space padding to be specified in <link
        linkend="guc-log-line-prefix"><varname>log_line_prefix</></link>
        (David Rowley)
       </para>
      </listitem>

      <listitem>
       <para>
        Add superuser-only <link
        linkend="guc-session-preload-libraries"><varname>session_preload_libraries</></link>
        configuration parameter to load libraries at session start
        (Peter Eisentraut)
       </para>

       <para>
        In contrast
        to <link linkend="guc-local-preload-libraries"><varname>local_preload_libraries</></link>,
        this parameter can load any shared library, not just those in
        the <filename>$libdir/plugins</> directory.
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce server logging level when loading shared libraries (Peter
        Geoghegan)
       </para>

       <para>
        The previous level was <literal>LOG</>, which was too verbose
        for per-session libraries.
       </para>
      </listitem>

      <listitem>
       <para>
        Increase <link
        linkend="guc-work-mem"><varname>work_mem</></link> and <link
        linkend="guc-maintenance-work-mem"><varname>maintenance_work_mem</></link>
        defaults by four times (Bruce Momjian)
       </para>

       <para>
        The new defaults are 4MB and 64MB respectively.
       </para>
      </listitem>

      <listitem>
       <para>
        Increase the default setting of <link
        linkend="guc-effective-cache-size"><varname>effective_cache_size</></link>
        to 4GB (Bruce Momjian, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow terabyte units to be specified for configuration variable
        values (Simon Riggs)
       </para>
      </listitem>

      <listitem>
       <para>
        Have Windows <acronym>ASCII</>-encoded databases and server process
        (e.g.  <link linkend="app-postmaster">postmaster) emit messages
        in the <envar>LC_CTYPE</></link>-defined language (Alexander Law,
        Noah Misch)
       </para>

       <para>
        Previously these messages were output using the Windows
        <acronym>ANSI</> code page.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="recovery-config"><filename>recovery.conf</></link>
        parameter <link linkend="recovery-min-apply-delay"><varname>recovery_min_apply_delay</></link>
        to delay replication (Robert Haas, Fabr&iacute;zio de Royes Mello,
        Simon Riggs)
       </para>

       <para>
        This is useful for delaying the replay of user errors on standby
        servers.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="recovery-target"><varname>recovery_target</></link>
        option <option>immediate</> to stop <link
        linkend="wal"><acronym>WAL</></link> recovery as soon as a
        consistent state is reached (MauMau, Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve recovery target processing (Heikki Linnakangas)
       </para>

       <para>
        The timestamp reported
        by <link linkend="functions-recovery-info-table"><function>pg_last_xact_replay_timestamp()</></link>
        now shows information about already-committed records, not of transactions
        about to be committed. Recovering to a restore point now replays the
        restore point, rather than stopping just before the restore point.
       </para>
      </listitem>

      <listitem>
       <para>
        <link
        linkend="functions-admin-backup-table"><function>pg_switch_xlog()</></link>
        now clears the trailing unused space in the <acronym>WAL</> file
        (Heikki Linnakangas)
       </para>

       <para>
        This improves the compression ratio for <acronym>WAL</> files.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="streaming-replication-slots">replication
        slots</link> to coordinate activity on streaming standbys with the
        node they are streaming from (Andres Freund, Robert Haas)
       </para>

       <para>
        Replication slots allow preservation of resources like
        <acronym>WAL</> files on the primary that are needed by standby
        servers.
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce spinlock contention during <acronym>WAL</> replay (Heikki
        Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Report failure return codes from <link
        linkend="archive-recovery-settings">external recovery commands</>
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Write <acronym>WAL</> records of running transactions more
        frequently (Andres Freund)
       </para>

       <para>
        This allows standby servers to start faster and cleanup resources
        more aggressively.
       </para>
      </listitem>

     </itemizedlist>

     <sect4>
      <title><link linkend="logicaldecoding">Logical Decoding</></title>

      <para>
       Logical decoding allows database changes to be optionally streamed in a
       configurable format. The data is read from
       the <link linkend="wal"><acronym>WAL</></link> and transformed into the
       desired target format. To implement this feature, the following changes
       were made:
      </para>

      <itemizedlist>
       <!-- FIXME: This imo needs a pretty fundamental rewrite -->
       <listitem>
        <para>
         Add new <option>logical</> <link
         linkend="guc-wal-level"><varname>wal_level</></link> to enable
         logical change-set encoding in <acronym>WAL</> (Andres Freund)
        </para>

        <para>
         This interacts with <link
         linkend="catalog-pg-class"><literal>REPLICA IDENTITY</></link>.
        </para>
       </listitem>

       <listitem>
        <para>
         Allow <link
         linkend="app-pgreceivexlog"><application>pg_recvlogical</></link>
         to receive data logical decoding data (Andres Freund)
        </para>
       </listitem>

       <listitem>
        <para>
         Add <link
         linkend="test-decoding"><application>test_decoding</></link>
         module to illustrate logical decoding at the <acronym>SQL</>
         level (Andres Freund)
        </para>
       </listitem>

       <listitem>
        <para>
         Allow logical decoding via the walsender interface ? (Andres
         Freund)
        </para>
       </listitem>

       <listitem>
        <para>
         Add table-level parameter <link
         linkend="catalog-pg-class"><literal>REPLICA IDENTITY</></link>
         to control logical replication (Andres Freund)
        </para>
       </listitem>

       <listitem>
        <para>
         Add relation option <link
         linkend="SQL-CREATETABLE-storage-parameters"><option>user_catalog_table</></link>
         to identify user-created tables involved in logical change-set
         encoding (Andres Freund)
        </para>
       </listitem>

      </itemizedlist>

     </sect4>

   </sect3>

   <sect3>
    <title>Queries</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="queries-tablefunctions"><literal>ROWS
        FROM()</></link> syntax to allow horizontal concatenation of
        set-returning functions in the <literal>FROM</>-clause (Andrew Gierth)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="queries-tablefunctions"><literal>WITH
        ORDINALITY</></link> syntax which numbers rows returned from
        <literal>FROM</>-clause functions (Andrew Gierth, David Fetter)
       </para>

       <para>
        This is particularly useful for functions like
        <function>unnest()</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="SQL-SELECT"><command>SELECT</></link> with
        an empty target list (Tom Lane)
       </para>

       <para>
        <!-- FIXME: drop? -->
        This was added so views that select from a table with zero columns
        can be dumped correctly.
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Utility Commands</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="SQL-DISCARD"><command>DISCARD
        SEQUENCES</></link> command to discard cached sequence information
        (Fabr&iacute;zio de Royes Mello, Robert Haas)
       </para>

       <para>
        <!-- FIXME: compatibility break entry? -->
        <command>DISCARD ALL</> will now also discard such information.
       </para>
      </listitem>

       <listitem>
        <para>
         Add <command>FORCE NULL</> option
         to <link linkend="SQL-COPY"><command>COPY FROM</></link> which causes
         quoted strings matching the null string to be converted to NULL in
         in <literal>CSV</> mode (Ian Barwick, Michael Paquier)
        </para>

        <para>
         Previously only unquoted matching strings would be imported
         as NULLs.
        </para>
       </listitem>

      <listitem>
       <para>
        Issue warnings for commands used outside of transaction blocks
        because they have no effect (Bruce Momjian)
       </para>

       <para>
        The cases are <literal>SET
        LOCAL</>, <literal>SET CONSTRAINTS</>, <literal>SET TRANSACTION</> and
        <literal>ABORT</>.
       </para>
      </listitem>

     </itemizedlist>

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

      <itemizedlist>

       <listitem>
        <para>
         Have <command>EXPLAIN ANALYZE</> output planning time (Andreas
         Karlsson)
        </para>
       </listitem>

       <listitem>
        <para>
         Have <command>EXPLAIN</> print the grouping columns in Agg and
         Group nodes (Tom Lane)
        </para>
       </listitem>

       <listitem>
        <para>
         Have <command>EXPLAIN ANALYZE</> show bitmap heap scan exact/lossy
         block information (Etsuro Fujita)
        </para>
       </listitem>

      </itemizedlist>

     </sect4>

     <sect4>
      <title>Views</title>

      <itemizedlist>

      <listitem>
       <para>
        Allow materialized views to be refreshed without blocking reads
         (Kevin Grittner)
       </para>

       <para>
        This is done with <link
        linkend="SQL-REFRESHMATERIALIZEDVIEW"><command>REFRESH MATERIALIZED
        VIEW CONCURRENTLY</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow views to be <link
        linkend="SQL-CREATEVIEW-updatable-views">automatically
        updated</link> even if they contain some non-updatable columns
        (Dean Rasheed)
       </para>

       <para>
        Previously the presence of non-updatable columns such as
        expressions, literals, and function calls prevented automatic
        updates.  Now <command>INSERT</>s, <command>UPDATE</>s and
        <command>DELETE</>s are supported, provided that they do not
        attempt to assign new values to any of the non-updatable columns.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow control over whether <command>INSERT</>s and
        <command>UPDATE</>s can add rows to an auto-updatable view that
        would no longer appear in the view (Dean Rasheed)
       </para>

       <para>
        This is controlled with the new <link
        linkend="SQL-CREATEVIEW"><literal>WITH CHECK OPTION</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="rules-privileges">security barrier views</>
        to be automatically updatable (Dean Rasheed)
       </para>
      </listitem>

      </itemizedlist>

     </sect4>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow triggers on <link linkend="SQL-CREATEFOREIGNTABLE">foreign
        tables</> (Ronan Dunklau)
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <command>DROP IF EXISTS</> to more consistently not error
        for non-existent objects (Pavel Stehule,  Dean Rasheed)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve the internal definition of system relations (Andres Freund,
        Robert Haas)
       </para>

       <para>
        Previously, relations once moved into the system catalog schema could
        no longer be modified or dropped.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="SQL-ALTERTABLESPACE"><command>ALTER
        TABLESPACE</></link> options to be also set by <link
        linkend="SQL-CREATETABLESPACE"><command>CREATE TABLESPACE</></link>
        (Vik Fearing)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="SQL-CREATEAGGREGATE"><command>CREATE
        AGGREGATE</></link> to supply the size of the aggregate's
        transition state data (Hadi Moshayedi)
       </para>
      </listitem>

     </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow moving groups of objects from one tablespace to another
        using <link linkend="SQL-ALTERTABLESPACE"><command>ALTER
        TABLESPACE</></link> ... <literal>MOVE</> (Stephen Frost)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow the changing of foreign key constraint  via <link
        linkend="SQL-ALTERTABLE"><command>ALTER TABLE</></link>
        ... <literal>ALTER CONSTRAINT</> (Simon Riggs)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce lock levels of some <link
        linkend="SQL-ALTERTABLE"><command>ALTER TABLE</></link> commands
        (Simon Riggs, Noah Misch)
       </para>

       <para>
        Specifically, <literal>VALIDATE CONSTRAINT</>, <literal>CLUSTER
        ON</>, <literal>SET WITHOUT CLUSTER</>, <literal>ALTER COLUMN
        SET STATISTICS</>, <literal>ALTER COLUMN</> <literal>SET</>
        <option>(attribute_option)</>, <literal>ALTER COLUMN RESET</>
        <option>(attribute_option)</> no longer require <literal>ACCESS
        EXCLUSIVE</> locks.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

      <listitem>
       <para>
        Fully-implement the <link
        linkend="datatype-line"><type>line</></link> data type (Peter
        Eisentraut)
       </para>

       <para>
        The line <emphasis>segment</> data type (<link
        linkend="datatype-lseg"><type>LSEG</></link>) has always been
        fully supported.  The previous <type>line</> data type (enabled
        only via a compile-time option) is not binary or dump-compatible.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="datatype-pg-lsn"><type>PG_LSN</></link>
        data type to represent a <acronym>WAL</> log sequence number
        (<acronym>LSN</>) (Robert Haas, Michael Paquier)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow single-point <link
        linkend="datatype-polygon"><type>POLYGON</></link>s to be converted
        to <link linkend="datatype-circle"><type>CIRCLE</></link>s
        (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow 5+ digit years for non-<acronym>ISO</> <link
        linkend="datatype-datetime"><type>TIMESTAMP</></link> and
        <type>DATE</> strings, where appropriate (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Add checks for overflow/underflow of <link
        linkend="datatype-datetime"><type>INTERVAL</></link> values
        (Bruce Momjian)
       </para>
      </listitem>

    </itemizedlist>

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

     <itemizedlist>

       <listitem>
        <para>
         Add structured (non-text) data type (<link
         linkend="datatype-json"><type>JSONB</></link>) for storing
         <type>JSON</> data (Oleg Bartunov, Teodor Sigaev, Alexander
         Korotkov, Peter Geoghegan, and Andrew Dunstan)
        </para>

        <para>
         This allows for faster access to values in the <type>JSON</>
         document and faster and more useful indexing of <type>JSON</>.
         <type>JSONB</> values are also typed as appropriate scalar
         SQL types.
        </para>
       </listitem>

       <listitem>
        <para>
         Add new <type>JSON</> functions to allow for the construction
         of arbitrarily complex json trees (Andrew Dunstan, Laurence Rowe)
        </para>

        <para>
         New functions include <link
         linkend="functions-json-processing-table"><function>json_array_elements_text()</></link>,
         <function>json_build_array()</>, <function>json_object()</>,
         <function>json_object_agg()</>, <function>json_to_record()</>,
         and <function>json_to_recordset()</>.
        </para>
       </listitem>

       <listitem>
        <para>
         Add <link
         linkend="functions-json-processing-table"><function>json_typeof()</></link>
         to return the data type of a <type>JSON</> value (Andrew Tipton)
        </para>
       </listitem>

     </itemizedlist>

    </sect4>

   </sect3>


   <sect3>
    <title>Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <link
        linkend="functions-datetime-delay"><function>pg_sleep_for(interval)</></link>
        and <function>pg_sleep_until(timestamp)</> to specify sophisticated
        delays (Vik Fearing, Julien Rouhaud)
       </para>

       <para>
        <function>pg_sleep()</> only supports delays specified in seconds.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="array-functions-table"><function>cardinality()</></link>
        function for arrays (Marko Tiikkaja)
       </para>

       <para>
        This returns the total number of elements in the array, or zero
        for an array with no elements.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>SQL</> functions to allow <link
        linkend="lo-interfaces">large object reads/writes</link> at
        arbitrary offsets (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link
        linkend="array-functions-table"><function>unnest()</></link>
        to take multiple arguments, which are individually unnested then
        horizontally concatenated (Andrew Gierth)
       </para>
      </listitem>

      <listitem>
       <para>
        Add functions to construct <type>time</>s, <type>date</>s,
        <type>timestamp</>s, <type>timestamptz</>s, and <type>interval</>s
        from individual values, rather than strings (Pavel Stehule)
       </para>

       <para>
        These functions are prefixed with <literal>make_</>,
        e.g. <link linkend="functions-datetime-table"><function>make_date()</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link
        linkend="functions-formatting-table"><function>to_char(<literal>TZ</>)</></link>
        return the proper value for constant time zone offsets (Tom Lane)
       </para>

       <para>
        Previously, <literal>to_char(CURRENT_TIMESTAMP, 'TZ')</> returned
        NULL if the <literal>TIME ZONE</> was set to a constant like
        <literal>-4</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add timezone offset output option <literal>OF</> to <link
        linkend="functions-formatting-table"><function>to_char()</></link>
        (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve the random seed used for <link
        linkend="functions-math-random-table"><function>random()</></link>
        (Honza Horak)
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title>System Information Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Add functions for looking up objects in <structname>pg_class</>,
        <structname>pg_proc</>, <structname>pg_type</>, and
        <structname>pg_operator</> which do not generate errors for
        non-existent objects (Yugo Nagata, Nozomi Anzai,
        Robert Haas)
       </para>

       <para>
        For example, <link
        linkend="functions-info-catalog-table"><function>to_regclass()</></link>
        does lookups of <structname>pg_class</> and returns NULL for
        non-existent objects.
       </para>
      </listitem>

      <listitem>
       <para>
        Add function <link
        linkend="functions-admin-dblocation"><function>pg_filenode_relation()</></link>
        to allow for more efficient filenode to relation lookups (Andres
        Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="information-schema"><structname>information_schema</></link>
        column <link
        linkend="infoschema-parameters"><structfield>parameters.parameter_default</></link>
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link
        linkend="infoschema-schemata"><structfield>information_schema.schemata</></link>
        show all accessible schema (Peter Eisentraut)
       </para>

       <para>
        Previously it only showed <emphasis>owned</> schemas.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Aggregates</title>

     <itemizedlist>

      <listitem>
       <para>
        Add aggregates <link
        linkend="functions-orderedset-table"><function>percentile_cont()</></link>,
        <function>percentile_disc()</>, <link
        linkend="functions-hypothetical-table"><function>rank()</></link>,
        <function>dense_rank()</>, <function>percent_rank()</>,
        <function>cume_dist()</>, and <link
        linkend="functions-orderedset-table"><function>mode()</></link>
        (Atri Sharma, Andrew Gierth)
       </para>
      </listitem>

      <listitem>
       <para>
        Add control over which values are passed
        into aggregate functions using the <link
        linkend="syntax-aggregates"><literal>FILTER</></link> clause
        (David Fetter)
       </para>
      </listitem>

      <listitem>
       <para>
        Support ordered-set (<link
        linkend="syntax-aggregates"><literal>WITHIN GROUP</></link>)
        aggregates (Atri Sharma, Andrew Gierth, Tom Lane)
       </para>

       <para>
        This allows aggregates that require sorted input.
       </para>
      </listitem>

      <listitem>
       <!-- FIXME -->
       <para>
        Allow polymorphic aggregates to have non-polymorphic state data
        types ? (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link
        linkend="xfunc-sql-variadic-functions"><literal>VARIADIC</></link>
        aggregate functions (Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

     <listitem>
      <para>
       Add event trigger support to <link linkend="plperl">PL/Perl</>
       and <link linkend="pltcl">PL/Tcl</> (Dimitri Fontaine)
      </para>
     </listitem>

    </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Add ability to store the PL/PgSQL
        call stack into a variable using <link
        linkend="plpgsql-get-diagnostics-context"><literal>PG_CONTEXT</></link>
        (Pavel Stehule, Stephen Frost)
       </para>
      </listitem>

      <listitem>
       <para>
        Add option <link
        linkend="plpgsql-statements-assignment"><option>print_strict_params</></link>
        to output parameters passed to queries generating <link
        linkend="plpgsql-statements-sql-onerow"><literal>STRICT</></link>
        errors (Marko Tiikkaja)
       </para>
      </listitem>

      <listitem>
       <para>
        Add variables <link
        linkend="plpgsql-extra-checks"><varname>plpgsql.extra_warnings</></link>
        and <varname>plpgsql.extra_errors</> to enable additional PL/pgSQL
        warnings and errors (Marko Tiikkaja, Petr Jelinek)
       </para>

       <para>
        Currently only shadowed variable errors/warnings are available.
       </para>
      </listitem>

    </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Convert <link linkend="datatype-numeric"><type>NUMERIC</></link>s
        to <type>decimal</> values in PL/Python (Szymon Guz, Ronan Dunklau)
       </para>

       <para>
        Previously these were converted to <type>float</>s.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title><link linkend="libpq"><application>libpq</></link></title>
     <itemizedlist>

      <listitem>
       <para>
        Add libpq function <link
        linkend="libpq-pqhostaddr"><function>PQhostaddr()</></link>
        to return the server's <acronym>IP</> address (Fujii Masao)
       </para>
      </listitem>

      <listitem>
       <para>
        Make libpq's <link
        linkend="libpq-pqconndefaults"><function>PQconndefaults()</></link>
        ignore invalid service files (Steve Singer, Bruce Momjian)
       </para>

       <para>
        Previously it returned NULL.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow libpq to support <acronym>TLS</> versions beyond
        <literal>TLSv1</> (Marko Kreen)
       </para>
      </listitem>

      <listitem>
       <para>
        Document that libpq's <link
        linkend="libpq-pqclientencoding"><function>PQclientEncoding()</></link>
        returns <literal>-1</> for an encoding lookup failure (Bruce
        Momjian)
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

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

    <itemizedlist>

      <listitem>
       <para>
        Add <link
        linkend="APP-CREATEUSER"><application>createuser</></link>
        <option>-g</> to specify role membership (Chistopher Browne)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="APP-VACUUMDB"><application>vacuumdb</></link>
        option <option>--analyze-in-stages</> to analyze in stages of
        increasing granularity (Peter Eisentraut)
       </para>

       <para>
        This allows minimal statistics to be created quickly.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="pgxlogdump"><application>pg_xlogdump</></link>
        to report a live log stream with <option>--follow</> (Heikki
        Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link linkend="APP-PGRESETXLOG"><command>pg_resetxlog
        -n</></link> output current and potentially changed values
        (Rajeev Rastogi)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <function>sizeof()</> in <link linkend="ecpg">ecpg</link>
        C array definitions (Michael Meskes)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link linkend="ecpg">ecpg</link> properly handle nesting
        requirements in C and <acronym>SQL</> mode for C-style comments
        (Michael Meskes)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link linkend="app-pg-ctl"><application>pg_ctl</></link>
        return <literal>4</> for an inaccessible data directory
        specification (Amit Kapila, Bruce Momjian)
       </para>

       <para>
        This more closely matches the Linux Standard Base (<acronym>LSB</>)
        Core Specification.
       </para>
      </listitem>

      <listitem>
       <para>
        On Windows, interpret <link
        linkend="app-pg-ctl"><application>pg_ctl</></link>'s non-absolute
        path <option>-D</> directories relative to <application>pg_ctl</>'s
        current directory (Kumar Rajeev Rastogi)
       </para>
      </listitem>

    </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow field wrapping to <application>psql</>'s "extended" mode
        (Sergey Muraviov)
       </para>
      </listitem>

      <listitem>
       <para>
        Suppress "No rows" in <application>psql</> <link
        linkend="APP-PSQL-meta-commands"><option>expanded</></link>
        mode when the footer is disabled (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow Control-C to abort <application>psql</> hung at connection
        startup (Peter Eisentraut)
       </para>
      </listitem>

     </itemizedlist>

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

      <itemizedlist>

       <listitem>
        <para>
         Have <application>psql</> <command>\db+</> show tablespace options
         (Magnus Hagander)
        </para>
       </listitem>

       <listitem>
        <para>
         Have <application>psql</> <command>\do+</> display the functions
         which implement the operators (Marko Tiikkaja)
        </para>
       </listitem>

       <listitem>
        <para>
         Have <application>psql</> <command>\d+</> output an
         <literal>OID</> line only if an oid column exists in a table
         (Bruce Momjian)
        </para>

        <para>
         Previously, the presence or absence of an oid column was always
         reported.
        </para>
       </listitem>

       <listitem>
        <para>
         Have <command>\d</> display disabled system triggers (Bruce
         Momjian)
        </para>

        <para>
         Previously if you disabled all triggers, only user triggers
         would show as disabled.
        </para>
       </listitem>

       <listitem>
        <para>
         Fix <application>psql</> <command>\copy</> to no longer require
         a space between <literal>stdin</> and a semicolon (Etsuro Fujita)
        </para>
       </listitem>

       <listitem>
        <para>
         Output the row count at the end of
         <application>psql</> <command>\copy</> just like <link
         linkend="SQL-COPY"><command>COPY</></link> (Kumar Rajeev Rastogi)
        </para>
       </listitem>

       <listitem>
        <para>
         Fix <application>psql</> <command>\conninfo</> to display the
         server's <acronym>IP</> address for clients that connect using
         <literal>hostaddr</> (Fujii Masao)
        </para>

        <para>
         Previously <command>\conninfo</> could not display the server's
         <acronym>IP</> address in such cases.
        </para>
       </listitem>

       <listitem>
        <para>
         Mention the <acronym>SSL</> protocol version in
         <application>psql</>'s <command>\conninfo</> (Marko Kreen)
        </para>
       </listitem>

       <listitem>
        <para>
         Add <application>psql</> tab completion for <command>\pset</>
         (Pavel Stehule)
        </para>
       </listitem>

       <listitem>
        <para>
         Allow <application>psql</> <command>\pset</> with no arguments
         to show all settings (Gilles Darold)
        </para>
       </listitem>

       <listitem>
        <para>
         In <application>psql</>, output the written history file name
         (<command>\s</>) without adding an absolute path prefix (Tom Lane)
        </para>

        <para>
         The previous output was inconsistent.
        </para>
       </listitem>

      </itemizedlist>

     </sect5>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow <link
        linkend="APP-PGRESTORE"><application>pg_restore</></link> options
        <option>-I</>, <option>-P</>, <option>-T</> and <option>-n</>
        to be specified multiple times (Heikki Linnakangas)
       </para>

       <para>
        This allows multiple restore object to be specified.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <literal>IF EXISTS</> clauses when removing old objects during
        dump and restore (Pavel Stehule)
       </para>

       <para>
        This suppresses errors when removing old objects.
        The new <option>--if-exists</> option to <link
        linkend="APP-PGDUMP"><application>pg_dump</></link>, <link
        linkend="APP-PG-DUMPALL"><application>pg_dumpall</></link>, and
        <link linkend="APP-PGRESTORE"><application>pg_restore</></link>
        is only available when <option>--clean</> is also specified.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="app-pgbasebackup"><application>pg_basebackup</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <application>pg_basebackup</> option <option>--xlogdir</>
        to specify the <filename>pg_xlog</> direction location (Haribabu
        Kommi)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pg_basebackup</> to relocate tablespaces in
        the backup copy (Steeve Lennmark)
       </para>

       <para>
        This is particularly useful for using <application>pg_basebackup</>
        on the same machine as the primary.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow network-streams base backups to be throttled (Antonin Houska)
       </para>

       <para>
        This can be controlled with the <application>pg_basebackup</>
        <option>--max-rate</> parameter.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Improve the way tuples are frozen, to preserve forensic information
        (Robert Haas, Andres Freund)
       </para>

       <para>
        Code that inspects tuple flag bits will need to be modified.
       </para>
      </listitem>

      <listitem>
       <para>
        No longer require function prototypes for function marked with the
        <link linkend="xfunc-c"><function>PG_FUNCTION_INFO_V1</></link>
        macro (Peter Eisentraut)
       </para>

       <para>
        This eliminates needless boilerplate prototypes whose lack
        generates compiler warnings.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <function>SnapshotNow()</> and
        <function>HeapTupleSatisfiesNow()</> (Robert Haas)
       </para>

       <para>
        All existing uses have been switched to more appropriate snapshot
        types.  Catalog scans now use <acronym>MVCC</> snapshots.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>API</> for memory allocations over four gigabytes
        (Noah Misch)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <function>psprintf()</> to simplify memory allocation during
        string composition (Peter Eisentraut, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <function>printf()</> modifier "z" to specify <type>size_t</>
        values (Andres Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Change <acronym>API</> of <function>appendStringInfoVA()</>
        to better use <function>vsnprintf()</> (David Rowley, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow new types of external toast datums to be created (Andres
        Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Add single-reader, single-writer, lightweight shared message queue
        (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve spinlock speed on x86_64 <acronym>CPU</>s (Heikki
        Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove spinlock support for unsupported platforms
        <productname>SINIX</>, <productname>Sun3</>, and
        <productname>NS32K</> (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <acronym>IRIX</> port (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce the number of semaphores required by
        <option>--disable-spinlocks</> (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Rewrite <application>duplicate_oids</> Unix shell script in
        <application>Perl</> (Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Add Test Anything Protocol (<acronym>TAP</>) tests for client
        programs (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add make targets <option>check-tests</> and
        <option>installcheck-tests</> which allow per-test specification
        (Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <option>maintainer-check</> makefile rule (Peter Eisentraut)
       </para>

       <para>
        Its functionality is now done by the default build rules.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve support for <envar>VPATH</> builds of <acronym>PGXS</>
        modules  (C&eacute;dric Villemain, Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Upgrade to Autoconf 2.69 (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add configure flag that appends custom text to the
        <envar>PG_VERSION</> string (Oskari Saarenmaa)
       </para>

       <para>
        This is useful for packagers building custom binaries.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve DocBook <acronym>XML</> validity (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Various security and sanity fixes reported by the
        <productname>Coverity</> scanner (Stephen Frost)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <application>valgrind</> error reporting (Noah Misch)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <application>Emacs</> configuration file
        <filename>emacs.samples</> (Peter Eisentraut)
       </para>

       <para>
        Also add <filename>.dir-locals.el</> to the top of the source tree.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pgindent</> to be supplied a command-line list
        of typedefs (Bruce Momjian)
       </para>

       <para>
        <application>Pgindent</> is also now smarter about blank lines
        around preprocessor conditionals.
       </para>
      </listitem>

      <listitem>
       <para>
        Avoid most uses of dlltool in <productname>Cygwin</> and
        <productname>Mingw</> builds (Marco Atzeri, Hiroshi Inoue)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow client-only installs for <acronym>MSVC</> (Windows) builds (MauMau)
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

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

    <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="pgprewarm"><application>pg_prewarm</></link>
        to preload relation data into the shared buffer cache (Robert Haas)
       </para>

       <para>
        This is useful at server start to produce more consistent
        performance.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>UUID</> random number generator
        <function>gen_random_uuid()</> to <link
        linkend="pgcrypto"><application>pgcrypto</></link> (Oskari
        Saarenmaa)
       </para>

       <para>
        This allows the creation of version 4 <acronym>UUID</>s without
        requiring the installation of uuid-ossp.
       </para>
      </listitem>

      <listitem>
       <para>
        Add logging of trigger execution to <link
        linkend="auto-explain"><application>auto_explain</></link>
        (Horiguchi Kyotaro)
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <link linkend="pgstattuple"><application>pgstattuple</></link>
        to not report rows from uncommitted transactions as dead
        (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link linkend="pgstattuple"><application>pgstattuple</></link>
        functions use regclass-type arguments (Satoshi Nagayasu)
       </para>

       <para>
        While text-type arguments are still supported, they will be
        removed in a later major release.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve consistency of <link
        linkend="pgrowlocks"><application>pgrowlocks</></link> output to
        honor snapshot rules more consistently (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve indexing of <link
        linkend="pgtrgm"><application>pg_trgm</></link> values to
        discourage indexing whitespace (Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
        Store <link linkend="cube"><type>cube</></link> data more compactly
        (Stas Kelvich)
       </para>

       <para>
        Existing data must be dumped/restored to use the new format.
        The old format can still be read.
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce <link linkend="vacuumlo"><application>vacuumlo</></link>
        client-side memory usage by using a cursor (Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Dramatically reduce memory consumption in <link
        linkend="pgupgrade"><application>pg_upgrade</></link> (Bruce
        Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Pass <link linkend="pgupgrade"><application>pg_upgrade</></link>
        user names (<option>-U</>) to analyze scripts (Bruce Momjian)
       </para>
      </listitem>

    </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow pgbench to process script files of any line length (Sawada
        Masahiko)
       </para>

       <para>
        The previous line limit was <envar>BUFSIZ</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <application>pg_bench</> option (<option>--rate</>) to control
        the transaction rate (Fabien Coelho)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <option>--progress</> output option to pgbench (Fabien Coelho)
       </para>
      </listitem>

      <listitem>
       <para>
        Add long options to pgbench (Fabien Coelho)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="pgstatstatements"><application>pg_stat_statements</></link></title>

     <itemizedlist>

      <listitem>
       <para>
        Have <application>pg_stat_statements</> use a flat file for query
        text storage (Peter Geoghegan)
       </para>

       <para>
        This removes the limitation on query text length, and allows a
        higher default number of unique statements to be tracked.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow reporting of <application>pg_stat_statements</>'s internal
        query hash identifier (Daniel Farina, Sameer Thakur, Peter
        Geoghegan)
       </para>
      </listitem>

      <listitem>
       <para>
        Add the ability to retrieve all <application>pg_stat_statements</>
        information except the query text (Peter Geoghegan)
       </para>

       <para>
        This allows monitoring tools to only fetch query text for newly
        created entries, as reported in <structfield>queryid</>.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

  </sect2>
 </sect1>
