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 <sect1 id="release-9-2">
  <title>Release 9.2</title>

  <note>
   <title>Release Date</title>
   <simpara>2012-??-??</simpara>
   <simpara>CURRENT AS OF 2012-05-09</simpara>

  </note>

  <sect2>
   <title>Overview</title>

   <para>
    NARRATIVE HERE. Major enhancements include:
   </para>

   <itemizedlist>
    <listitem><para>MAJOR LIST HERE</para></listitem>
    <!-- This list duplicates items below, but without authors or details-->

   </itemizedlist>

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

  </sect2>

  <sect2>

  <title>Migration to Version 9.2</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 9.2 contains a number of changes that may affect compatibility
    with previous releases.  Observe the following incompatibilities:
   </para>

   <sect3>
    <title>Functions</title>

    <itemizedlist>

      <listitem>
       <para>
        Ensure that <link
        linkend="functions-xml-processing"><function>xpath()</></link>
        escapes special characters in string values (Florian Pflug,
        Radoslaw Smogura)
       </para>

       <para>
        Without this it is possible to output illegal
        <acronym>XML</acronym>.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <link linkend="hstore">hstore</link>'s <literal>=&gt;</>
        operator (Robert Haas, David Wheeler)
       </para>

       <para>
        Users should now use hstore(text, text).  Since
        <productname>PostgreSQL</productname> 9.0, a warning message is
        emitted when an operator named =&gt; is created because
        the <acronym>SQL</acronym> standard reserves that token for
        another use.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link
        linkend="functions-admin-dbobject"><function>pg_relation_size()</></link>
        and friends return NULL if the object does not exist (Phil Sorber)
       </para>

       <para>
        This prevents queries that call these functions from returning
        errors during concurrent drop operations.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove the <link
        linkend="catalog-pg-tablespace"><structname>spclocation</></link>
        field from <structname>pg_tablespace</> (Magnus Hagander,
        Tom Lane)
       </para>

       <para>
        This field was duplicative of the symbolic links already
        present in the data directory.  This allows tablespace
        directories to be moved while the server is down.  Also add
        <function>pg_tablespace_location()</> to allow querying of the
        symbolic links.
       </para>
      </listitem>

    </itemizedlist>

    <sect4>
     <title>Temporal Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Have <link
        linkend="functions-datetime-extract"><function>EXTRACT</></link> of
        a non-timezone-aware value measure the epoch from local midnight,
        not <acronym>UTC</acronym> midnight (Tom Lane)
       </para>

       <para>
        Having these computations depend on <acronym>UTC</acronym>
        was inconsistent.  The old behavior is available by casting the
        value to timestamp with time zone.
       </para>
      </listitem>

      <listitem>
       <para>
        Properly parse time strings with trailing <literal>yesterday</>,
        <literal>today</>, and <literal>tomorrow</> (Dean Rasheed)
       </para>

       <para>
        Previously, <command>SELECT '04:00:00
        yesterday'::timestamp</command> returned yesterday's date at
        midnight.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <link
        linkend="functions-formatting"><function>to_date()</></link> and
        <function>to_timestamp()</> to wrap incomplete dates toward 2020
        (Bruce Momjian)
       </para>

       <para>
        Previously, supplied years and year masks of less than four digits
        wrapped inconsistently.
       </para>
      </listitem>

     </itemizedlist>
    </sect4>

    </sect3>

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

    <itemizedlist>

      <listitem>
       <para>
        Prevent  <link linkend="SQL-ALTERDOMAIN"><command>ALTER
        DOMAIN</command></link> from working on non-domain types (Peter
        Eisentraut)
       </para>

       <para>
        Owner and schema changes were previously possible on non-domain
        types.
       </para>
      </listitem>

      <listitem>
       <para>
        No longer auto-lowercase procedural language names (Robert Haas)
       </para>

       <para>
        While unquoted language identifiers are still lowercased, strings
        and quoted identifiers are no longer forcibly down-cased.
        Thus for example <literal>CREATE FUNCTION ... LANGUAGE 'C'</>
        will no longer work; it must be spelled <literal>'c'</>, or better
        omit the quotes.
       </para>
      </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Command-Line Tools</title>

    <itemizedlist>

      <listitem>
       <para>
        Provide consistent backquote, variable
        expansion, and quoted substring behavior in <link
        linkend="APP-PSQL"><application>psql</></link> meta-command
        arguments (Tom Lane)
       </para>

       <para>
        Previously, such usage was only properly expanded when isolated by
        whitespace, e.g.  <literal>'FOO'BAR</> was output as <literal>FOO
        BAR</>.
       </para>
      </listitem>

      <listitem>
       <para>
        No longer treat <link
        linkend="APP-CLUSTERDB"><application>clusterdb</></link>
        table names as double-quoted; no longer treat <link
        linkend="APP-REINDEXDB"><application>reindexdb</></link> table
        and index names as double-quoted (Bruce Momjian)
       </para>

       <para>
        Users must supply double-quotes in the command arguments to
        accomplish double-quoting behavior.
       </para>
      </listitem>

      <listitem>
       <para>
        Disable prompting for the user name in <link
        linkend="APP-DROPDB"><application>dropdb</></link> unless
        <option>--interactive</> is specified (Peter Eisentraut, Josh
        Kupershmidt)
       </para>
      </listitem>

      <listitem>
       <para>
        No longer have <link
        linkend="APP-CREATEUSER"><application>createuser</></link> prompt
        for settings (Peter Eisentraut, Josh Kupershmidt)
       </para>

       <para>
        Previously <application>createuser</> prompted regarding various
        user settings.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <link linkend="APP-INITDB"><application>initdb</></link>
        support for the crypt authentication method (Peter Eisentraut)
       </para>

       <para>
        This was removed from the backend years ago.
       </para>
      </listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>
      <listitem>
       <para>
        Remove the <filename>postgresql.conf</filename> setting
        <varname>silent_mode</> (Heikki Linnakangas)
       </para>

       <para>
        This behavior could already be accomplished with <command>pg_ctl
        -l postmaster.log</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <acronym>GUC</acronym> <varname>wal_sender_delay</>,
        as it is no longer needed (Tom Lane)
       </para>

       <para>
        The new "latch" capability made this setting unnecessary.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove the <varname>custom_variable_classes</>
        <filename>postgresql.conf</filename> parameter (Tom Lane)
       </para>

       <para>
        The checking provided by this setting was dubious.  Now any
        setting can be prefixed by any class name.
       </para>
      </listitem>

      <listitem>
       <para>
        Add GUC <link linkend="guc-ssl-key-file">parameters</link> for
        specifying the locations of server-side <acronym>SSL</acronym>
        files (Peter Eisentraut)
       </para>

       <para>
        This allows changing the location of the files that were previously
        hard-coded to <filename>server.crt</>, <filename>server.key</>,
        <filename>root.crt</>, <filename>root.crl</>.  <acronym>CA</>
        (crt) and <acronym>CRL</acronym> files no longer have default
        names, and if specified, these files must exist.
       </para>
      </listitem>

    </itemizedlist>
   </sect3>

   <sect3>
    <title>Monitoring</title>

    <itemizedlist>

      <listitem>
       <para>
        Rename <link
        linkend="monitoring-stats-views-table"><structname>pg_stat_activity</></link><structname>.procpid</>
        to <structname>pid</>, to match other system tables (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Create a separate <structname>pg_stat_activity</> column to
        report state information, e.g. idle (Scott Mead, Magnus Hagander,
        Greg Smith)
       </para>

       <para>
        The last query values are preserved, allowing for enhanced analysis.
       </para>
      </listitem>

      <listitem>
       <para>
        Rename <structname>pg_stat_activity.current_query</> to
        <structname>query</> because it is not cleared when the query
        completes (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Change all <acronym>SQL</acronym>-level statistics timing values
        to float8-stored milliseconds (Tom Lane)
       </para>

       <para>
        The columns affected are:
        <structname>pg_stat_user_functions.total_time</>,
        <structname>pg_stat_user_functions.self_time</>,
        <structname>pg_stat_xact_user_functions.total_time</>,
        <structname>pg_stat_xact_user_functions.self_time</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Change <application>pg_stat_statements</>'
        <structname>total_time</> column to be measured in milliseconds
        (Tom Lane)
       </para>
      </listitem>

    </itemizedlist>

   </sect3>

  </sect2>

  <sect2>
   <title>Changes</title>

   <para>
    Below you will find a detailed account of the changes between
    <productname>PostgreSQL</productname> 9.2 and the previous major
    release.
   </para>

   <sect3>
    <title>Server</title>

    <sect4>
     <title>Performance</title>

     <itemizedlist>
      <listitem>
       <para>
        Allow queries to retrieve data only from indexes, avoiding heap
        access (Robert Haas, Ibrar Ahmed, Tom Lane)
       </para>

       <para>
        This is often called "index-only scans" or "covering indexes".
        This is possible for heap pages with exclusively all-visible
        tuples, as reported by the visibility map.  The visibility map was
        made crash-safe as a necessary part of implementing this feature.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow frequently uncontended locks to be recorded using a new
        lightweight lock mechanism (Robert Haas, Jeff Davis)
       </para>
      </listitem>

      <listitem>
       <para>
        Move the frequently accessed members of the <structname>PGPROC</>
        shared memory array to a separate section, for performance (Pavan
        Deolasee, Heikki Linnakangas, Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce overhead of creating virtual transaction id locks (Robert
        Haas, Jeff Davis)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce overhead for shared invalidation cache messages (Robert
        Haas, Noah Misch)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance of transactions using many savepoints (Simon
        Riggs, Robert Haas)  PARTIALLY REVERTED.  KEEP?
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <command>COPY</command> performance by adding tuples to
        the heap in batches (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve GiST box and point index performance by producing better
        trees with less memory allocation overhead (Alexander Korotkov,
        Heikki Linnakangas, Kevin Grittner)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow hint bits to be set sooner for temporary and unlogged tables
        (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce checkpoints and <acronym>WAL</acronym> traffic on low
        activity servers (Simon Riggs)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow sorting to be performed by inlined and faster,
        non-<acronym>SQL</acronym>-callable comparison functions (Peter
        Geoghegan, Robert Haas, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add the <link linkend="SPGiST">SP-GiST</link> (Space-Partitioned
        GiST) index access method (Teodor Sigaev, Oleg Bartunov, Tom Lane,
        Robert Haas)
       </para>

       <para>
        SP-GiST is comparable to GiST in flexibility, but supports
        non-balanced partitioned search structures rather than balanced
        trees.  CLARIFY?
       </para>
      </listitem>

      <listitem>
       <para>
        Improve GiST index build times (Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
        Take fewer <acronym>MVCC</acronym> snapshots, for performance
        (Robert Haas, Dimitri Fontaine)
       </para>
      </listitem>

      <listitem>
       <para>
        Have the number of clog buffer count scale based on <link
        linkend="guc-shared-buffers"><varname>shared_buffers</></link>
        (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce the overhead of serializable isolation level locks (Dan
        Ports, Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve locking performance during group commit (Peter Geoghegan,
        Simon Riggs, Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve PowerPC and Itanium spinlock performance (Manabu Ori,
        Tom Lane, Robert Haas)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Process Management</title>

     <itemizedlist>

      <listitem>
       <para>
        Create a dedicated worker process to perform checkpoints (Simon
        Riggs, Dickson Guedes)
       </para>

       <para>
        Formerly the background writer did dirty page writing and
        checkpointing.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve asynchronous commit behavior by waking up sooner (Simon
        Riggs)
       </para>

       <para>
        Previously, only <link
        linkend="guc-wal-writer-delay"><varname>wal_writer_delay</></link>
        triggered <acronym>WAL</acronym> flushing to disk; now filling a
        <acronym>WAL</acronym> buffer also triggers <acronym>WAL</acronym>
        writes.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow backends to detect postmaster death via a pipe read failure,
        rather than polling (Peter Geoghegan, Heikki Linnakangas)
       </para>

       <para>
        The wait events are internally called "latches".
       </para>
      </listitem>

      <listitem>
       <para>
        Allow the <link linkend="pg-stat-bgwriter-view">bgwriter</link>,
        <link linkend="guc-wal-writer-delay">walwriter</link>, <link
        linkend="monitoring-stats">statistics collector</link>, archiver,
        and checkpointer to sleep more efficiently during periods of
        inactivity (Peter Geoghegan, Heikki Linnakangas, Tom Lane)
       </para>

       <para>
        This reduces <acronym>CPU</acronym> wake-ups, which dramatically
        reduces power consumption on idle servers.
       </para>
      </listitem>

      <listitem>
       <para>
        Pass the safe number of file descriptors to Windows processes
        (Heikki Linnakangas)
       </para>

       <para>
        This allows Windows sessions to cache more open file descriptors.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Optimizer</title>

     <itemizedlist>

      <listitem>
       <para>
        Improve the ability of the planner to choose parameterized plans
        (Tom Lane)
       </para>

       <para>
        A prepared statement is now parsed, analyzed, and rewritten,
        but not necessarily planned.  When the prepared plan is executed
        with parameters, the planner might replan it for every constant,
        or it might execute a generic plan if its cost is close to that
        of a constant-specific plan. CLARIFY
       </para>
      </listitem>

      <listitem>
       <para>
        Allow the optimizer to use <literal>CHECK</> constraints defined
        on tables referenced in subqueries in planning decisions (Tom Lane)
       </para>

       <para>
        This is only enabled when <link
        linkend="guc-constraint-exclusion"><literal>constraint_exclusion
        = on</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <literal>indexedcol op ANY(ARRAY[...])</> conditions to be
        used in plain indexscans (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve heuristics for determining the type of unknown values by
        considering other data types involved in the operation (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow better matching of index columns with non-default operator
        qualifications (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve the planner's ability to use nested loops with inner
        index scans (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Support <function>MIN</>/<function>MAX</> index optimizations on
        boolean columns (Marti Raudsepp, Abhijit Menon-Sen)
       </para>
      </listitem>

     </itemizedlist>

    <sect5>
     <title>Optimizer Statistics</title>

     <itemizedlist>
      <listitem>
       <para>
        Improve the ability to use statistics on columns referenced in
        subqueries (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve optimizer estimation for subqueries using
        <literal>DISTINCT</> (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Collect and use element-frequency statistics for arrays (Alexander
        Korotkov, Noah Misch, Nathan Boley, Tom Lane, Daniele Varrazzo)
       </para>

       <para>
        This patch improves selectivity estimation for the array &lt;@,
        &amp;&amp;, and @&gt; (containment and overlaps) array operators.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve costing of partial indexes (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow analyze statistics to be collected for foreign tables
        (Etsuro Fujita, Shigeru Hanada, Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

    </sect5>

    </sect4>

    <sect4>
     <title>Authentication</title>

     <itemizedlist>

      <listitem>
       <para>
        Do not assume roles and <literal>samerole</> specified in <link
        linkend="auth-pg-hba-conf"><filename>pg_hba.conf</filename></link>
        include superusers (Andrew Dunstan, Robert Haas)
       </para>

       <para>
        This makes it easier to use reject lines with group roles.
       </para>
      </listitem>

      <listitem>
       <para>
        Make superuser imply replication privilege (Noah Misch)
       </para>

       <para>
        This avoids the need to explicitly assign such privileges.
       </para>
      </listitem>

      <listitem>
       <para>
        Adjust <filename>pg_hba.conf</filename> processing to more
        consistently handle token parsing (Brendan Jurd, &Aacute;lvaro
        Herrera, Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Disallow empty <filename>pg_hba.conf</filename> files (Tom Lane)
       </para>

       <para>
        This was done to more quickly report misconfiguration.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Monitoring</title>

     <itemizedlist>

      <listitem>
       <para>
        Attempt to log the current query string before a backend crash
        (Marti Raudsepp, <acronym>PDXPUG</>, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Make logging of autovacuum I/O activity more verbose (Greg Smith,
        Noah Misch)
       </para>

       <para>
        This logging is triggered by <link
        linkend="guc-log-autovacuum-min-duration"><varname>log_autovacuum_min_duration</></link>.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <acronym>WAL</acronym> replay report failures sooner
        (Fujii Masao)
       </para>

       <para>
        There were some cases where failures were only reported once the
        server went into master mode.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="functions-admin-backup"><function>pg_xlog_location_diff()</></link>
        to simplify xlog comparisons (Euler Taveira de Oliveira, Fujii
        Masao, Magnus Hagander)
       </para>

       <para>
        This is useful for computing replication lag.
       </para>
      </listitem>

      <listitem>
       <para>
        Support configurable eventlog application names on Windows (MauMau,
        Magnus Hagander)
       </para>

       <para>
        This allows different instances to use the eventlog
        with different identifiers, by setting the <link
        linkend="guc-event-source"><varname>event_source</></link>
        <acronym>GUC</acronym>, which is similar to how <link
        linkend="guc-syslog-ident"><varname>syslog_ident</></link> works.
       </para>
      </listitem>

      <listitem>
       <para>
        Change "unexpected EOF" message to <literal>DEBUG1</> level
        (Magnus Hagander)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Track temporary file sizes and file counts in the <link
        linkend="monitoring-stats-views"><structname>pg_stat_database</></link>
        system view (Tomas Vondra)
       </para>
      </listitem>

      <listitem>
       <para>
        Add a deadlock counter to the <structname>pg_stat_database</>
        system view (Magnus Hagander, Jaime Casanova)
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <acronym>GUC</acronym> setting <link
        linkend="guc-track-io-timing"><varname>track_io_timing</></link>
        to track I/O timings (Ants Aasma, Greg Smith, Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Report checkpoint timing information in <link
        linkend="pg-stat-bgwriter-view"><structname>pg_stat_bgwriter</></link>
        (Greg Smith, Peter Geoghegan, Robert Haas)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow <link
        linkend="guc-deadlock-timeout"><varname>deadlock_timeout</></link>
        to be set per-session by superusers, not just per-cluster (Noah
        Misch, Shigeru Hanada)
       </para>

       <para>
        This allows <varname>deadlock_timeout</> to be reduced for
        transactions that are likely to be involved in a deadlock,
        thus detecting it more quickly. It can also be used to reduce
        the chances of a session being chosen for cancellation due to
        a deadlock.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>GUC</acronym> parameter <link
        linkend="guc-temp-file-limit"><varname>temp_file_limit</></link>
        to constrain temporary file space usage per session (Mark Kirkwood,
        C&eacute;dric Villemain, Tatsuo Ishii)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <filename>postgresql.conf</filename> category "Replication /
        Sending Servers" (Fujii Masao)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow a superuser to <command>SET</command> an extension's
        superuser-only custom variable before loading the associated
        extension (Tom Lane)
       </para>

       <para>
        The system now remembers whether a <command>SET</command> was
        performed by a superuser.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="app-postmaster">postmaster</link> <option>-C</>
        option to query configuration parameters (Bruce Momjian)
       </para>

       <para>
        This allows <application>pg_ctl</> to better handle
        configuration-only directory installations.
       </para>
      </listitem>

      <listitem>
       <para>
        Force the locale to be recorded more specifically, rather than
        using the empty string to mean the default (Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

     <sect5>
      <title><filename>postgresql.conf</filename></title>

      <itemizedlist>

      <listitem>
       <para>
        Allow multiple errors in <filename>postgresql.conf</filename>
        to be reported, rather than just the first one (Alexey Klyukin,
        Andy Colson)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow a reload of <filename>postgresql.conf</filename> to be
        processed by all backends even if there are some settings that
        are invalid for that session (Alexey Klyukin, Andy Colson)
       </para>

       <para>
        Previously, such not-valid-for-session errors would cause all
        setting changes to be ignored by that backend.
       </para>
      </listitem>

      <listitem>
       <para>
        Add an <literal>include_if_exists</> facility for configuration
        files (Greg Smith, Euler Taveira de Oliveira)
       </para>

       <para>
        This works the same as <literal>include</>, except that an error
        is not thrown if the file is missing.
       </para>
      </listitem>

      <listitem>
       <para>
        Check the server time zone during initdb, and set
        <filename>postgresql.conf</filename> values
        <link linkend="guc-timezone"><varname>timezone</></link> and
        <link linkend="guc-log-timezone"><varname>log_timezone</></link>
        accordingly (Tom Lane)
       </para>

       <para>
        This avoids expensive time zone probes during server start.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow Windows to report
        <filename>postgresql.conf</filename> line numbers in <link
        linkend="view-pg-settings"><structname>pg_settings</></link>
        (Tom Lane)
       </para>
      </listitem>

      </itemizedlist>

     </sect5>

    </sect4>

   </sect3>

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

   <sect4>
    <title>Streaming Replication</title>

    <itemizedlist>

      <listitem>
       <para>
        Allow streaming replications slaves to serve other slaves (Fujii
        Masao, Simon Riggs)
       </para>

       <para>
        Previously, only the master server could supply streaming
        replication log files to standby servers.  Slaves can also now
        do continuous archiving. (?)
       </para>
      </listitem>

      <listitem>
       <para>
        Add new <link
        linkend="guc-synchronous-commit"><varname>synchronous_commit</></link>
        replication mode <literal>remote_write</> (Fujii Masao and
        Simon Riggs)
       </para>

       <para>
        This only writes data to the socket, but does not wait a write
        to the remote disk.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <link
        linkend="app-pgreceivexlog"><application>pg_receivexlog</></link>
        tool to archive xlog file changes as they are written, rather
        than waiting for completed xlog files (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Send keepalive messages to standby servers (Simon Riggs)
       </para>

       <para>
        This allows administrators to accurately calculate streaming
        replication transfer and application latency.
       </para>
      </listitem>

     </itemizedlist>

     <sect5>
      <title><link linkend="app-pgbasebackup"><application>pg_basebackup</></link></title>

      <itemizedlist>

      <listitem>
       <para>
        Allow streaming of xlog files while <application>pg_basebackup</>
        is performing a backup (Magnus Hagander)
       </para>

       <para>
        This allows passing of xlog files to the standby before they are
        discarded on the primary.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pg_basebackup</> to pull from standby servers
        (Jun Ishizuka, Fujii Masao)
       </para>
      </listitem>

      <listitem>
       <para>
        Exclude the postmaster.opts file from <application>pg_basebackup</>
        backups (Magnus Hagander)
       </para>
      </listitem>

      </itemizedlist>

     </sect5>
    </sect4>

   </sect3>

   <sect3>
    <title>Queries</title>

     <itemizedlist>

      <listitem>
       <para>
        Improve columns labels produced by subqueries (Marti Raudsepp,
        Kyotaro Horiugchi)
       </para>

       <para>
        Previously, the generic label <literal>?column?</> was used.
       </para>
      </listitem>

      <listitem>
       <para>
        Preserve column names in row expressions (Andrew Dunstan, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Cancel queries if clients get disconnected (Florian Pflug, Greg
        Jaskiewicz)
       </para>
      </listitem>

      <listitem>
       <para>
        Silently ignore nonexistent schemas specified in <link
        linkend="guc-search-path"><varname>search_path</></link> (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Warn about casts to and from domain types (Robert Haas)
       </para>

       <para>
        Such casts have no effect.
       </para>
      </listitem>

      <listitem>
       <para>
        When a row fails a <literal>CHECK</> or <literal>NOT NULL</>
        constraint, show the row's contents in errdetail (Jan
        Kundr&aacute;t, Royce Ausburn, Tom Lane)
       </para>

       <para>
        This should make it easier to identify which row is problematic
        when an insert or update is processing many rows.
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Provide more reliable operation during concurrent
        <acronym>DDL</acronym> (Robert Haas, Noah Misch)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <literal>CONCURRENTLY</> option to <link
        linkend="SQL-DROPINDEX"><command>DROP INDEX
        CONCURRENTLY</command></link> (Simon Riggs)
       </para>

       <para>
        This allows index removal without blocking other sessions.
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title>Constraints</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow <link linkend="ddl-constraints"><literal>CHECK</></link>
        constraints to be declared <literal>NOT VALID</> (&Aacute;lvaro
        Herrera, Thom Brown, Dean Rasheed, Jaime Casanova)
       </para>

       <para>
        A <literal>NOT VALID</> <literal>CHECK</> constraint can be added
        to a table without the table's data being verified against the
        constraint.  New rows are verified.
       </para>

       <para>
        Such constraints are ignored by the planner when considering
        <varname>constraint_exclusion</>.  <command>ALTER TABLE</command> /
        <literal>VALIDATE</> allows <literal>NOT VALID</> <literal>CHECK</>
        check constraints to be fully validated and considered for
        <varname>constraint_exclusion</>, including re-planning of
        cached plans.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <literal>CHECK</> constraints to be declared <literal>NO
        INHERIT</> (Nikhil Sontakke, Alex Hunsaker)
       </para>

       <para>
        This makes them enforceable only on the parent table, not on
        child tables.
       </para>
      </listitem>

      <listitem>
       <para>
        Add the ability to <link linkend="SQL-ALTERTABLE">rename</link>
        constraints (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Disallow merging of <literal>ONLY</> and non-<literal>ONLY</>
        constraints in child tables (Nikhil Sontakke)
       </para>

       <para>
        Such merging would cause unpredictable behavior in grandchild
        tables.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Reduce need to rebuild tables and indexes for various <link
        linkend="SQL-ALTERTABLE"><command>ALTER TABLE</command></link>
        operations (Noah Misch) DUPLICATE?
       </para>
      </listitem>

      <listitem>
       <para>
        Add <literal>IF EXIST</> clause to <command>ALTER</command>
        commands (Pavel Stehule)
       </para>

       <para>
        For example, <command>ALTER FOREIGN TABLE IF EXISTS foo RENAME
        TO bar</command>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="SQL-ALTERFOREIGNDATAWRAPPER"><command>ALTER
        FOREIGN DATA WRAPPER</command></link> / <literal>RENAME</>
        and <link linkend="SQL-ALTERSERVER"><command>ALTER
        SERVER</command></link> / <literal>RENAME</> (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="SQL-ALTERDOMAIN"><command>ALTER
        DOMAIN</command></link> / <literal>RENAME</> (Peter Eisentraut)
       </para>

       <para>
        You could already rename domains using <command>ALTER
        TYPE</command>.
       </para>
      </listitem>

      <listitem>
       <para>
        Throw an error for <command>ALTER DOMAIN</command> / <literal>DROP
        CONSTRAINT</> on a nonexistent constraint (Peter Eisentraut)
       </para>

       <para>
        An <literal>IF EXISTS</> option has been added to enable the
        previous behavior.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Fix <command>CREATE TABLE</command> ... <literal>AS EXECUTE</>
        to handle <literal>WITH NO DATA</> and column name specification
        (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Support <command>CREATE TABLE (LIKE ...)</command> from foreign
        tables and views (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <command>CREATE TABLE (LIKE ...)</command> from composite
        type (Peter Eisentraut)
       </para>

       <para>
        This also allows a table to be created whose schema matches a view.
       </para>
      </listitem>

      <listitem>
       <para>
        Tighten creation of tables in temporary schemas (Robert Haas)
       </para>

       <para>
        Previously, it was possible to create unlogged tables in temporary
        schemas, and temporary tables in the temporary schemas of other
        sessions.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Add a <link
        linkend="SQL-CREATEVIEW"><literal>security_barrier</></link>
        option for views (KaiGai Kohei, Noah Misch)
       </para>

       <para>
        This prevents <literal>security_barrier</> views from being moved
        into other scopes, preventing possible leakage of view-prohibited
        data.  Such views might perform more poorly.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a new <link
        linkend="SQL-CREATEFUNCTION"><literal>LEAKPROOF</></link> function
        specification to mark functions that can be safely pushed down
        into <literal>security_barrier</> views (KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for privileges on date types (Peter Eisentraut,
        Yeb Havinga)
       </para>

       <para>
        This adds support for the <acronym>SQL</>-conforming
        <literal>USAGE</> privilege on types and domains.  The intent is
        to be able restrict which users can create dependencies on types,
        which restricts the way in which owners can alter types.
       </para>
      </listitem>

      <listitem>
       <para>
        Check for <command>INSERT</command> privileges in <command>SELECT
        INTO</command> / <command>CREATE TABLE AS</command> (KaiGai Kohei,
        Albe Laurenz)
       </para>

       <para>
        Because the object is being created by <command>SELECT
        INTO</command> or <command>CREATE TABLE AS</command>, it will
        have default insert permissions, except if <literal>ALTER DEFAULT
        PRIVILEGES</> has removed such permissions, hence the need for
        a permission check.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

      <listitem>
       <para>
        Allow vacuum to more easily skip pages that cannot be locked
        (Simon Riggs, Robert Haas)
       </para>

       <para>
        This change should greatly reduce the incidence of vacuum getting
        "stuck".
       </para>
      </listitem>

    </itemizedlist>

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

      <itemizedlist>

      <listitem>
       <para>
        Make <command>EXPLAIN (BUFFERS)</command> track blocks dirtied
        and written (Robert Haas, Fujii Masao, Greg Smith)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <command>EXPLAIN ANALYZE</command> report the number of rows
        rejected by filter steps (Marko Tiikkaja, Marc Cousin)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <command>EXPLAIN</command> to avoid timing overhead when
        time values are unwanted (Tomas Vondra, Eric Theise)
       </para>

       <para>
        This is accomplished by setting <literal>TIMING</> to
        <literal>FALSE</>.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

      <listitem>
       <para>
        Add a <link linkend="datatype-json"><type>JSON</type></link>
        data type (Robert Haas)  AUTHOR?
       </para>

       <para>
        This stores <acronym>JSON</acronym> data as text after proper
        validation.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link
        linkend="functions-json"><function>array_to_json()</></link>
        and <function>row_to_json()</> (Andrew Dunstan, Abhijit Menon-Sen)
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for <link linkend="rangetypes">range data types</link>
        (Jeff Davis, Tom Lane, Alexander Korotkov)
       </para>

       <para>
        The range data type records a lower and upper bound, and supports
        operations like contains, overlaps, and intersection.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="datatype-serial"><type>SMALLSERIAL</></link>
        data type (Mike Pultz, Brar Piening, Josh Kupershmidt)
       </para>

       <para>
        This is like <type>SERIAL</>, except it stores the sequence in
        a two-byte integer column (int2).
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link linkend="SQL-CREATEDOMAIN">domains</link> to be
        declared <literal>NOT VALID</> (&Aacute;lvaro Herrera, Thom Brown,
        Dean Rasheed, Jaime Casanova, Peter Eisentraut)
       </para>

       <para>
        This can be set at domain creation time, or via
        <command>ALTER DOMAIN</command> / <literal>ADD CONSTRAINT / NOT
        VALID</>. <command>ALTER DOMAIN</command> / <literal>VALIDATE
        CONSTRAINT</> fully validates the domain.
       </para>
      </listitem>

      <listitem>
       <para>
        Support more locale-specific formatting options for the <link
        linkend="datatype-money">MONEY</link> data type (Tom Lane)
       </para>

       <para>
        Specifically, display the plus/minus sign, currency symbol,
        and separators in a locale-specific order.  CORRECT?
       </para>
      </listitem>

      <listitem>
       <para>
        Add bitwise "and", "or", and "not" <link
        linkend="macaddr-functions-table">operators</link> for the macaddr
        data type (Brendan Jurd, Fujii Masao)
       </para>
      </listitem>

    </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow <function>xpath()</> to return a single-element
        <acronym>XML</acronym> array when supplied a scalar value (Florian
        Pflug, Radoslaw Smogura)
       </para>

       <para>
        Previously, it returned an empty array.  This change will also
        cause <function>xpath_exists()</> to return true, not false,
        for such expressions.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <acronym>XML</acronym> error handling to be more robust
        (Florian Pflug, Tom Lane, Noah Misch)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow users to cancel queries in user-matching sessions using <link
        linkend="functions-admin-signal"><function>pg_cancel_backend()</></link>
        (Magnus Hagander)
       </para>

       <para>
        Previously only the superuser could cancel queries.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <link
        linkend="functions-aggregate-table"><function>string_agg()</></link>
        to process bytea values (Pavel Stehule, Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow regular expressions to use back-references (Tom Lane)
       </para>

       <para>
        For example, '^(\w+)( \1)+$'.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow importing and exporting of transaction snapshots (Joachim
        Wieland, Marko Tiikkaja, Tom Lane)
       </para>

       <para>
        Snapshots are exported via <link
        linkend="functions-snapshot-synchronization"><function>pg_export_snapshot()</></link>,
        and imported via <command>SET TRANSACTION SNAPSHOT</command>.
        Only snapshots of currently-running transactions can be imported.
       </para>
      </listitem>

      <listitem>
       <para>
        Support <link
        linkend="functions-info-catalog-table"><literal>COLLATION
        FOR</></link> on expressions (Peter Eisentraut, Jaime Casanova)
       </para>

       <para>
        This returns a string representing the collation of the expression.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <type>NUMERIC</> variant of <link
        linkend="functions-admin-dbsize"><function>pg_size_pretty()</></link>
        for use with <function>pg_xlog_location_diff()</> (Fujii Masao)
       </para>
      </listitem>

     </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Change default names of triggers to fire "action" triggers before
        "check" triggers (Tom Lane)
       </para>

       <para>
        This allows default-named check triggers to check post-action rows.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <link
        linkend="functions-info-session-table"><function>pg_trigger_depth()</></link>
        function (Kevin Grittner)
       </para>

       <para>
        This reports the current trigger call depth.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>
      <listitem>
       <para>
        Add <link
        linkend="functions-info-schema-table"><function>pg_opfamily_is_visible()</></link>
        (Josh Kupershmidt)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow per-column foreign data wrapper options and
        <literal>force_not_null</> (Shigeru Hanada, KaiGai Kohei)
       </para>

       <para>
        This allows <acronym>SQL</acronym> specification of per-column
        information useful to foreign data sources.  Includes
        <application>psql</> option display support.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve pretty printing of view definitions (Andrew Dunstan,
        Hitoshi Harada)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="information-schema">Information Schema</link></title>

     <itemizedlist>

      <listitem>
       <para>
        Add <structname>information_schema</> views
        <structname>role_udt_grants</>, <structname>udt_privileges</>,
        and <structname>user_defined_types</> (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add composite-type attributes to the
        <varname>information_schema</>.<varname>element_types</> view
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Implement information schema <varname>interval_type</> columns
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add collation columns to various information schema views (Peter
        Eisentraut)
       </para>

       <para>
        Specifically, provide collation columns for views referencing
        attributes, columns, domains, and <varname>element_types</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add display of sequence <literal>USAGE</> privileges to information
        schema (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <varname>with_hierarchy</> column to the information schema
        privileges display (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Have the information schema show default privileges (Peter
        Eisentraut, Abhijit Menon-Sen)
       </para>

       <para>
        Previously, default permissions generated <literal>NULL</> fields.
        (WAS IT NULL?)
       </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>
        Allow the PL/pgSQL <command>OPEN</> cursor command to supply
        parameters by name (Yeb Havinga, Kevin Grittner, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <command>GET STACKED DIAGNOSTICS</command> PL/pgSQL command
        to retrieve exception info (Pavel Stehule, Shigeru Hanada,
        David Wheeler)
       </para>
      </listitem>

      <listitem>
       <para>
        Speed up PL/pgSQL array assignment by caching type information
        (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve performance and memory consumption of the PL/pgSQL
        <literal>ELSIF</> clauses (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Output the function signature, not just the name, in PL/pgSQL
        error messages (Pavel Stehule, Abhijit Menon-Sen, Tom Lane)
       </para>
      </listitem>

    </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Properly handle empty arrays returned by PL/Perl functions
        (Andrew Dunstan) DETAILS?
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Add PL/Python <acronym>SPI</acronym> cursor support (Jan
        Urbanski, Steve Singer)
       </para>

       <para>
        This allows PL/Python to read partial result sets.
       </para>
      </listitem>

      <listitem>
       <para>
        Add result metadata functions to PL/Python (Peter Eisentraut,
        Abhijit Menon-Sen)
       </para>

       <para>
        Specifically, this adds result object functions .colnames,
        .coltypes, and .coltypmods.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="xfunc-sql">SQL</link> Server-Side Language</title>

     <itemizedlist>
      <listitem>
       <para>
        Allow <acronym>SQL</acronym>-language functions to reference
        parameters by name (Matthew Draper, Hitoshi Harada)
       </para>

       <para>
        To use this, simply name the function arguments and reference
        the argument names in the <acronym>SQL</acronym> function body.
       </para>
      </listitem>

     </itemizedlist>
    </sect4>

   </sect3>

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

    <itemizedlist>

      <listitem>
       <para>
        Add <link linkend="APP-INITDB"><application>initdb</></link>
        options <option>--auth-local</> and <option>--auth-host</>
        (Peter Eisentraut, Pavel Stehule)
       </para>

       <para>
        This allows individual control of <literal>local</> and
        <literal>host</> <filename>pg_hba.conf</filename> authentication
        settings.  <option>--auth</> still controls both.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <option>--replication</>/<option>--no-replication</> flags to
        <link linkend="APP-CREATEUSER"><application>createuser</></link>
        to control replication permission (Fujii Masao, C&eacute;dric
        Villemain)
       </para>
      </listitem>

      <listitem>
       <para>
        Add the <option>--if-exists</> option to <link
        linkend="APP-DROPDB"><application>dropdb</></link> and <link
        linkend="APP-DROPUSER"><application>dropuser</></link> (Josh
        Kupershmidt)
       </para>
      </listitem>

      <listitem>
       <para>
        Give command-line tools the ability to specify the name of the
        database to connect to, and fall back to <varname>template1</>
        if a <literal>postgres</> database connection fails (Robert Haas)
       </para>
      </listitem>

    </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Add <application>psql</> mode to auto-expand output based on the
        display width (Peter Eisentraut, Noah Misch)
       </para>

       <para>
        This adds the <literal>auto</> option to the <command>\x</>
        command, which switches to the expanded mode when the normal
        output would be wider than the screen.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow inclusion of <application>psql</> files relative to the
        directory of the input file from which it was invoked (Gurjeet
        Singh, Josh Kupershmidt)
       </para>

       <para>
        The <application>psql</> command is <command>\ir</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for non-<acronym>ASCII</acronym> characters in
        <application>psql</> variable names (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for major-version-specific <filename>.psqlrc</> files
        (Bruce Momjian)
       </para>

       <para>
        <application>psql</> already supported minor-version-specific
        <filename>.psqlrc</>
        files.
       </para>
      </listitem>

      <listitem>
       <para>
        Provide environment variable overrides for <application>psql</>
        history and startup file locations (Andrew Dunstan)
       </para>

       <para>
        Specifically, <envar>PSQL_HISTORY</envar> and
        <envar>PSQLRC</envar>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <application>psql</> <command>\setenv</> command to modify
        the environment variables used by child processes (Andrew Dunstan,
        Josh Kupershmidt)
       </para>

       <para>
        This is useful in <filename>.psqlrc</> files.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <application>psql</> temporary editor files use a
        <filename>.sql</> extension (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Allows <application>psql</> to use zero-byte field and record
        separators (Peter Eisentraut, Abhijit Menon-Sen)
       </para>

       <para>
        Various shell tools use zero/null-byte separators, e.g. find.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <application>psql</> <command>\timing</> report times for
        failed queries (Magnus Hagander)
       </para>

       <para>
        Previously only successful query times were reported.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <application>psql</> <command>\copy</> use libpq's
        <function>SendQuery()</> (Noah Misch)
       </para>

       <para>
        This makes <command>\copy</> failure behavior more predictable,
        and honors <envar>ON_ERROR_ROLLBACK</>.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Informational Commands</title>

     <itemizedlist>
      <listitem>
       <para>
        Make <application>psql</> <command>\d</> on a sequence show the
        table/column name owning it (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Show statistics target for columns in <application>psql</>
        <command>\d+</> (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Show role password expiration dates in <application>psql</>
        <command>\du</> (Fabr&iacute;zio de Royes Mello)
       </para>
      </listitem>

     </itemizedlist>


    <sect5>
     <title>Comments</title>

     <itemizedlist>
      <listitem>
       <para>
        Allow <application>psql</> to display comments for languages and
        casts (Josh Kupershmidt)
       </para>

       <para>
        These are output via <command>\dL</> and <command>\dC</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>psql</> to display comments for conversions
        and domains (Josh Kupershmidt)
       </para>

       <para>
        This is accomplished with the addition of <literal>+</> to
        <command>\dc</> and <command>\dD</> commands.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>psql</> to display the comments on
        <acronym>SQL</acronym>/<acronym>MED</acronym> objects in verbose
        mode (Josh Kupershmidt)
       </para>
      </listitem>

      <listitem>
       <para>
        Change <application>psql</>'s <command>\dd</> command to display
        only objects without their own backslash command (Josh Kupershmidt)
       </para>
      </listitem>

     </itemizedlist>

    </sect5>

    </sect4>

    <sect4>
     <title>Tab Completion</title>

     <itemizedlist>

      <listitem>
       <para>
        In <application>psql</> tab completion,
        complete <acronym>SQL</acronym> keywords based on
        <varname>COMP_KEYWORD_CASE</> setting and the perhaps case of
        the partially-supplied word (Peter Eisentraut, Fujii Masao)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <application>psql</> tab completion support for
        <command>EXECUTE</command> (Andreas Karlsson, Josh Kupershmidt)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow tab completion of role references in
        <command>GRANT</command>/<command>REVOKE</command> (Peter
        Eisentraut, Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow tab completion of file names to supply quotes, when necessary
        (Noah Misch)
       </para>
      </listitem>

      <listitem>
       <para>
        Change <application>psql</> tab completion support for
        <command>TABLE</command> to also display views (Magnus Hagander)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Add an <option>--exclude-table-data</> option to
        <application>pg_dump</> (Andrew Dunstan)
       </para>

       <para>
        This allows dumping of a table's definition but not its data,
        on a per-table basis.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <option>--section</> option to <application>pg_dump</>
        and <application>pg_restore</> (Andrew Dunstan, Joachim Wieland)
       </para>

       <para>
        Valid values are <literal>pre-data</>, <literal>data</>,
        and <literal>post-data</>. The option can be
        given more than once. <option>--schema-only</>
        is equivalent to <literal>--section=pre-data
        --section=post-data</>. <option>--data-only</> is equivalent to
        <literal>--section=data</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link
        linkend="APP-PG-DUMPALL"><application>pg_dumpall</></link> dump all
        roles first, then all configuration settings on roles (Phil Sorber)
       </para>

       <para>
        This allows a role's configuration settings to rely on other
        roles without generating an error.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pg_dumpall</> to avoid errors if the
        <literal>postgres</> database is missing in the new cluster
        (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Dump foreign server user mappings in user name order (Peter
        Eisentraut)
       </para>

       <para>
        This helps produce deterministic dump files.
       </para>
      </listitem>

      <listitem>
       <para>
        Dump operators in a predictable order (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Tighten rules for when extension configuration tables are dumped
        by <application>pg_dump</> (Tom Lane)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Add <acronym>URI</acronym>s support to libpq connection functions
        (Alexander Shulgin)
       </para>

       <para>
        The syntax begins with <literal>postgres://</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a libpq <link linkend="libpq-connect-sslcompression">connection
        option</link> to disable <acronym>SSL</acronym> compression
        (Laurenz Albe)
       </para>

       <para>
        This can be used to remove the overhead of <acronym>SSL</acronym>
        compression on fast networks.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a row processor <acronym>API</acronym> to libpq for better
        handling of large result sets (Kyotaro Horiguchi, Marko Kreen)
       </para>

       <para>
        Previously, libpq collected the entire query result into memory
        before passing it back to the application.
       </para>
      </listitem>

      <listitem>
       <para>
        Enhance <literal>const</> qualifiers in the libpq functions
        PQconnectdbParams, PQconnectStartParams, and PQpingParams (Lionel
        Elie Mamane, Craig Ringer)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow libpq's <filename>.pgpass</> file to process escaped characters
        in the password field (Robert Haas, Ross Reedstrom)
       </para>
      </listitem>

      <listitem>
       <para>
        Have library functions use <function>abort()</> instead of
        <function>exit()</> to terminate the executable (Peter Eisentraut)
       </para>

       <para>
        This does not interfere with the normal exit codes used by the
        program, and generates a signal that can be caught by the caller.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix a libpq memory leak by freeing client encoding connection
        parameters (Peter Eisentraut)
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Add support for building with <link linkend="install-windows">MS
        Visual Studio 2010</link> (Brar Piening, Craig Ringer)
       </para>
      </listitem>

      <listitem>
       <para>
        Enable compiling with the MinGW-w64 32-bit compiler (Lars Kanis,
        Nishiyama Tomoaki)
       </para>
      </listitem>

      <listitem>
       <para>
        Install <filename>plpgsql.h</> into <filename>include/server</> during installation
        (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Use C flexible array members, where supported (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve the concurrent transaction regression tests
        (isolationtester) (Noah Misch, Alexander Shulgin)
       </para>
      </listitem>

      <listitem>
       <para>
        Modify <application>thread_test</> to create its test files in
        the current directory, rather than /tmp (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve flex and bison warning and error reporting (Tom Lane,
        Noah Misch)
       </para>
      </listitem>

      <listitem>
       <para>
        Add memory barrier support (Robert Haas)
       </para>

       <para>
        This is currently unused.
       </para>
      </listitem>

      <listitem>
       <para>
        Modify pgindent to use a typedef file (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Add a hook for processing messages due to be sent to the server
        log (Martin Pihlak, Marti Raudsepp)
       </para>
      </listitem>

      <listitem>
       <para>
        Add object access hooks for <command>DROP</command> commands
        (KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
        Centralize <command>DROP</command> handling for some object types
        (KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <application>pg_upgrade</> test suite (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Sync regular expression code with <acronym>TCL</acronym> 8.5.11
        and improve internal processing (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Move <acronym>CRC</acronym> tables to libpgport, and provide them
        in a separate include file (Daniel Farina, Abhijit Menon-Sen)
       </para>
      </listitem>

      <listitem>
       <para>
        Add options to <application>git_changelog</> for use in major
        release note creation (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove dead ports (Peter Eisentraut)
       </para>

       <para>
        The removed ports are: dgux, nextstep, sunos4, svr4, ultrix4,
        univel, bsdi.
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Modules</title>

    <itemizedlist>

      <listitem>
       <para>
        Improve efficiency of <link linkend="dblink">dblink</link> by
        using libpq's new row processor <acronym>API</acronym> (Kyotaro
        Horiguchi, Marko Kreen)
       </para>

       <para>
        This cannot be used by
        <function>dblink_send_query()</>/<function>dblink_get_result()</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <link linkend="tcn">tcn</link> (triggered change notification)
        to generate <command>NOTIFY</command> events on table changes
        (Kevin Grittner)
       </para>
      </listitem>

      <listitem>
       <para>
        Implement dry-run mode for <link
        linkend="pgarchivecleanup"><application>pg_archivecleanup</></link>
        (Gabriele Bartolini, Josh Kupershmidt)
       </para>

       <para>
        This only outputs the names of files to be deleted.
       </para>
      </listitem>

      <listitem>
       <para>
        Add new <link linkend="pgbench">pgbench</link> switches
        <option>--unlogged-tables</>, <option>--tablespace</>, and
        <option>--index-tablespace</> (Robert Haas)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link linkend="vacuumlo">vacuumlo</link> remove large objects
        in batches, to reduce locking (Tim Lewis, Josh Kupershmidt,
        Tom Lane)
       </para>

       <para>
        The new <option>-l</> option allows changing the number of large
        objects removed per transaction.
       </para>
      </listitem>

      <listitem>
       <para>
        Change <link
        linkend="pgtestfsync"><application>pg_test_fsync</></link> to test
        for a fixed amount of time, rather than a fixed number of cycles
        (Bruce Momjian)
       </para>

       <para>
        The <option>-o</>/cycles option was removed, and
        <option>-s</>/seconds added.
       </para>
      </listitem>

      <listitem>
       <para>
        Add a <link
        linkend="pgtesttiming"><application>pg_test_timing</></link>
        utility to measure clock monotonicity and timing overhead (Ants
        Aasma, Greg Smith)
       </para>
      </listitem>

    </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Allow <application>pg_upgrade</> to upgrade an old cluster that
        does not have a <literal>postgres</> database (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pg_upgrade</> to handle cases where some
        old or new databases are missing, as long as they are empty
        (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pg_upgrade</> to handle configuration-only
        directory installations (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        In <application>pg_upgrade</>, add <option>-o</>/<option>-O</>
        options to pass parameters to the servers (Bruce Momjian)
       </para>

       <para>
        This is useful for configuration-only directory installs.
       </para>
      </listitem>

      <listitem>
       <para>
        Change <application>pg_upgrade</> to use port 50432 by default
        (Bruce Momjian)
       </para>

       <para>
        This helps avoid unintended client connections during the upgrade.
       </para>
      </listitem>

      <listitem>
       <para>
        Overhaul <application>pg_upgrade</> logging and failure reporting
        (Bruce Momjian)
       </para>

       <para>
        Create four append-only log files, and delete them on success.
        Add <option>-r</>/<option>--retain</> option to unconditionally
        retain these files.  Also remove <application>pg_upgrade</> options
        <option>-g</>/<option>-G</>/<option>-l</> options as unnecessary,
        and tighten log file permissions.
       </para>
      </listitem>

      <listitem>
       <para>
        Adjust <application>pg_upgrade</> environment variables (Bruce
        Momjian)
       </para>

       <para>
        Rename data, bin, and port environment
        variables to begin with <literal>PG</>, and support
        <envar>PGPORTOLD</envar>/<envar>PGPORTNEW</envar>, to replace
        <envar>PGPORT</envar>.  INCOMPATIBILITY?
       </para>
      </listitem>

      <listitem>
       <para>
        Have <application>pg_upgrade</> create a script to incrementally
        generate more accurate optimizer statistics (Bruce Momjian)
       </para>

       <para>
        This reduces the time needed to generate minimal cluster statistics
        after an upgrade.
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce cluster locking in <application>pg_upgrade</> (Bruce
        Momjian)
       </para>

       <para>
        Specifically, only lock the old cluster if link mode is used,
        and do it right after the schema is restored.
       </para>
      </listitem>

    </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Improve <application>pg_stat_statements</> to aggregate similar
        queries (Peter Geoghegan, Daniel Farina, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <application>pg_stat_statements</>' handling of
        <command>PREPARE</command>/<command>EXECUTE</command> statements
        (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add dirtied and written block counts to
        <application>pg_stat_statements</> (Robert Haas, Fujii Masao,
        Greg Smith)
       </para>
      </listitem>

    </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="sepgsql">sepgsql</link></title>

     <itemizedlist>
      <listitem>
       <para>
        Support <literal>SECURITY LABEL</> on global objects (KaiGai Kohei,
        Robert Haas)
       </para>

       <para>
        Specifically, add <literal>SECURITY LABEL</>s to databases,
        tablespaces, and roles.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow sepgsql to honor database labels (KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
        Perform sepgsql permission checks during the creation of various
        objects (KaiGai Kohei, Dimitri Fontaine)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <function>sepgsql_setcon()</> and related functions to control
        the sepgsql security domain (KaiGai Kohei, Yeb Havinga)
       </para>
      </listitem>

      <listitem>
       <para>
        Add a userspace access cache to sepgsql to improve performance
        (KaiGai Kohei)
       </para>
      </listitem>

     </itemizedlist>
    </sect4>

   </sect3>

   <sect3>
    <title>Documentation</title>

    <itemizedlist>

      <listitem>
       <para>
        Add a rule to optionally build docs with the stylesheet from the
        website (Magnus Hagander)
       </para>

       <para>
        Use <command>make STYLE=website draft</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Improve <command>EXPLAIN</command> documentation (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Document that user/database names are preserved with double-quoting
        by command-line tools like <application>vacuumdb</>  (Bruce
        Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve the foreign data wrapper <acronym>API</acronym> and
        documentation (Hanada Shigeru, KaiGai Kohei)
       </para>
      </listitem>

      <listitem>
       <para>
        Document the actual string returned by the client for MD5
        authentication (Cyan Ogilvie)
       </para>
      </listitem>

    </itemizedlist>

   </sect3>

  </sect2>
 </sect1>
