postgresql/doc/src/sgml/release-9.5.sgml

<!-- doc/src/sgml/release-9.5.sgml -->
<!-- See header comment in release.sgml about typical markup -->

 <sect1 id="release-9-5">
  <title>Release 9.5</title>

  <note>
   <title>Release Date</title>
   <para>AS OF 2015-06-01</para>
   <simpara>2015-XX-XX</simpara>
  </note>

  <sect2>
   <title>Overview</title>

   <para>
    Major enhancements in <productname>PostgreSQL</> 9.5 include:
   </para>

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

   <itemizedlist>

    <listitem>
     <para>
     </para>
    </listitem>

   </itemizedlist>

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

  </sect2>

  <sect2>

  <title>Migration to Version 9.5</title>

   <para>
    A dump/restore using <xref linkend="app-pg-dumpall">, or use
    of <xref linkend="pgupgrade">, is required for those wishing to migrate
    data from any previous release.
   </para>

   <para>
    Version 9.5 contains a number of changes that may affect compatibility
    with previous releases.  Observe the following incompatibilities:
   </para>

   <itemizedlist>

    <listitem>
     <para>
      Adjust operator precedence to match the <acronym>SQL</> standard
      (Tom Lane)
     </para>

     <para>
      "&lt;" and "&gt;" now have the same precedence as "&lt;="
      "&gt;=" and "&lt;&gt;", and <literal>IS</> now has lower
      precedence.  <literal>NOT</> now also has symmetric precedence.
      The <acronym>GUC</> <varname>operator_precedence_warning</> can be
      enabled to warn about queries where the precedence has changed.
     </para>
    </listitem>

    <listitem>
     <para>
      Use cast conversions for <application>PL/pgSQL</> type conversions,
      rather than converting to and from text (Tom Lane)
     </para>

     <para>
      This causes conversions of booleans to strings to
      return <literal>true</> or <literal>false</>, not
      <literal>t</>/<literal>f</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow special characters in server startup option values to be
      escaped with a backslash (Andres Freund)
     </para>

     <para>
      This allows characters like spaces to be passed inside option values.
      Passing a backslash now requires supplying a double-backslash.
     </para>
    </listitem>

    <listitem>
     <para>
      Set the default value of <varname>include_realm</> to not remove
      the <acronym>GSS</> and <acronym>SSPI</> realm from the principal
      (Stephen Frost)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>REASSIGN</> and <command>ALTER OWNER TO</> to properly
      reassign ownership of types, foreign data wrappers, and foreign
      servers (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove server-side <acronym>GUC</> <varname>autocommit</>, which
      was already deprecated and non-operational (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove <structname>pg_authid</>.<structname>rolcatupdate</>, as it
      had no purpose (Adam Brightwell)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>

  <sect2>
   <title>Changes</title>

   <para>
     Below you will find a detailed account of the changes between
    <productname>PostgreSQL</productname> 9.5 and the previous major
     release.
   </para>

   <sect3>
    <title>Server</title>

    <sect4>
     <title>Indexes</title>

     <itemizedlist>

      <listitem>
       <para>
        Add Block Range Indexes (<acronym>BRIN</>) (&Aacute;lvaro Herrera,
        Heikki Linnakangas, Emre Hasegeli)
       </para>

       <para>
        <acronym>BRIN</> indexes are very compact and store the min/max
        values for a range of heap blocks.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow queries to perform accurate distance filtering of
        bounding-box-indexed objects (polygons, circles) using GiST indexes
        (Alexander Korotkov, Heikki Linnakangas)
       </para>

       <para>
        Previously, a common table expression was required to return a
        large number of rows ordered by bounding-box distance, and then
        filtered further with a more accurate non-bounding-box distance
        calculation.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow GiST indexes to perform index-only scans (Anastasia
        Lubennikova, Heikki Linnakangas, Andreas Karlsson)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>GUC</> <varname>gin_pending_list_limit</> to control
        the size of <acronym>GIN</> pending lists (Fujii Masao)
       </para>

       <para>
        Previously this was controlled by <varname>work_mem</>.  This can
        also be set as an index storage parameter.
       </para>
      </listitem>

      <listitem>
       <para>
        Issue a warning during the creation of hash indexes because they
        are not crash-safe (Bruce Momjian)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Improve the speed of sorting character and numeric fields (Robert
        Haas, Peter Geoghegan, Andrew Gierth)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve hash creation performance (Tomas Vondra, Teodor Sigaev,
        Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve concurrency of shared buffer replacement (Robert Haas,
        Amit Kapila)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve concurrent locking and buffer scan performance (Andres
        Freund, Kevin Grittner)
       </para>
      </listitem>

      <listitem>
       <para>
        Speed up <acronym>CRC</> (cyclic redundancy check) computations
        (Abhijit Menon-Sen, Heikki Linnakangas)
       </para>

       <para>
        Also use <acronym>CPU</> instructions for <acronym>CRC</>
        calculations, if supported
       </para>
      </listitem>

       </itemizedlist>

    </sect4>

    <sect4>
     <title>Monitoring</title>

     <itemizedlist>

      <listitem>
       <para>
        Add per-table autovacuum logging control via
        <varname>log_min_autovacuum_duration</> (Michael Paquier)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>GUC</> variable <varname>cluster_name</> (Thomas
        Munro)
       </para>

       <para>
        This string, set in <filename>postgresql.conf</>, allows clients
        to query the cluster name.  This name also appears in the process
        title, allowing for easier grouping of processes belonging to
        the same cluster.
       </para>
      </listitem>

      <listitem>
       <para>
        Prevent non-superusers from changing <varname>log_disconnections</>
        on connection startup (Fujii Masao)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Check <quote>Subject Alternative Names</> in <acronym>SSL</>
        server certificates, if present (Alexey Klyukin)
       </para>

       <para>
        Their presence replaces checks against the certificate's
        <quote>Common Name</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add system view <structname>pg_stat_ssl</> to report
        <acronym>SSL</> connection information (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <application>libpq</> function <function>PQsslAttribute()</>
        that returns <acronym>SSL</> information (Heikki Linnakangas)
       </para>

       <para>
        While <function>PQgetssl()</> can still be used
        to then call <productname>OpenSSL</> functions,
        <function>PQsslAttribute()</> returns <acronym>SSL</>
        information in an <acronym>SSL</>-implementation-independent way.
        (Future versions of libpq might support other <acronym>SSL</>
        implementations.)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <application>libpq</> honor any <productname>OpenSSL</>
        thread callbacks (Jan Urbanski)
       </para>

       <para>
        Previously they were overwritten.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
       <para>
        Replace <varname>checkpoint_segments</> with
        <varname>min_wal_size</> and <varname>max_wal_size</> (Heikki
        Linnakangas)
       </para>

       <para>
        This allows the allocation of a large number of <acronym>WAL</>
        files without keeping them if they are not needed.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>GUC</> <varname>wal_compression</> to enable
        compression of full page images stored in <acronym>WAL</>
        (Rahila Syed, Michael Paquier)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow the recording of transaction commit timestamps when
        <acronym>GUC</> <varname>track_commit_timestamp</> is enabled
        (&Aacute;lvaro Herrera, Petr Jelinek)
       </para>

       <para>
        Timestamp information can be accessed using
        functions <function>pg_xact_commit_timestamp()</> and
        <function>pg_last_committed_xact()</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <varname>local_preload_libraries</> to be set by
        <command>ALTER ROLE SET</> (Peter Eisentraut, Kyotaro Horiguchi)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow running autovacuum workers to respond to configuration
        parameter changes (Michael Paquier)
       </para>
      </listitem>

      <listitem>
       <para>
        Make <acronym>GUC</> <varname>debug_assertions</> read-only
        (Andres Freund)
       </para>

       <para>
        This means that assertions can no longer be turned off once enabled
        at compile-time, allowing for more efficient code optimization.
        This also removed the postgres <option>-A</> option.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow setting <varname>effective_io_concurrency</> on systems
        where it has no effect (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Add environment variables <envar>PG_OOM_ADJUST_FILE</> and
        <envar>PG_OOM_ADJUST_VALUE</> to control Linux <acronym>OOM</>
        killer (Gurjeet Singh)
       </para>

       <para>
        The previous <acronym>OOM</> control involved a compile-time
        option.
       </para>
      </listitem>

      <listitem>
       <para>
        Add function and view <function>pg_file_settings</> to show
        the source of <acronym>GUC</> values set in configuration files
        (Sawada Masahiko)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <structname>pending_restart</> to the system view
        <structname>pg_settings</> to indicate a change is pending a
        restart (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <command>ALTER SYSTEM</> values to be reset with
        <command>ALTER SYSTEM RESET</> (Vik Fearing)
       </para>

       <para>
        This removes the setting from <filename>postgresql.auto.conf</>.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Add <filename>recovery.conf</> parameter
        <varname>recovery_target_action</> to control post-recovery
        activity (Petr Jelinek)
       </para>

       <para>
        <acronym>GUC</> <varname>pause_at_recovery_target</> was also
        removed.
       </para>
      </listitem>

        
      <listitem>
       <para>
        Add <varname>archive_mode</> <literal>always</> to allow standbys
        to always archive received <acronym>WAL</> files (Fujii Masao)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>GUC</> <varname>wal_retrieve_retry_interval</> to
        control <acronym>WAL</> read retry after failure (Alexey Vasiliev,
        Michael Paquier)
       </para>

       <para>
        This is particularly helpful for warm standbys.
       </para>
      </listitem>

      <listitem>
       <para>
        Archive <acronym>WAL</> files with suffix <literal>.partial</>
        during standby promotion (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>GUC</> <varname>log_replication_commands</> to log
        replication commands (Fujii Masao)
       </para>

       <para>
        By default, replication commands,
        e.g. <literal>IDENTIFY_COMMAND</>, are not logged, even when
        <varname>log_statements</> is set to <literal>all</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow the labeling of the origin of logical replication changes
        (Andres Freund)
       </para>

       <para>
        This helps with change tracking.
       </para>
      </listitem>

      <listitem>
       <para>
        Report the backends holding replication slots in
        <structname>pg_replication_slots</> (Craig Ringer)
       </para>

       <para>
        The new output column is <structname>active_pid</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <filename>recovery.conf</>'s <varname>primary_conninfo</>
        to use connection <acronym>URI</>s, e.g. <literal>postgres://</>
        (Alex Shulgin)
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

   <sect3>
    <title>Queries</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow <command>INSERTS</> that would generate constraint conflicts
        to be turned into <command>UPDATE</>s or ignored (Peter Geoghegan,
        Heikki Linnakangas, Andres Freund)
       </para>

       <para>
        The syntax is <command>INSERT ... ON CONFLICT DO NOTHING/UPDATE</>.
        This is the Postgres implementation of the popular
        <command>UPSERT</> command.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <literal>GROUP BY</> analysis functions <literal>GROUPING
        SETS</>, <literal>CUBE</> and <literal>ROLLUP</> (Andrew Gierth,
        Atri Sharma)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow multi-column <command>UPDATE</>s with a single subselect
        (Tom Lane)
       </para>

       <para>
        This is accomplished using the syntax <command>UPDATE tab SET
        (col1, col2, ...) = (SELECT ...)</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Add new <command>SELECT</> option <literal>SKIP LOCKED</> to skip
        locked rows (Thomas Munro)
       </para>

       <para>
        This does not throw an error for locked rows like
        <literal>NOWAIT</> does.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <command>SELECT</> option <literal>TABLESAMPLE</> to return
        a subset of a table (Petr Jelinek)
       </para>
      </listitem>

      <listitem>
       <para>
        Suggest possible matches for mistyped column names (Peter
        Geoghegan, Robert Haas)
       </para>
      </listitem>

     </itemizedlist>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Add more details about sort ordering in <command>EXPLAIN</> output
        (Marius Timmer, Lukas Kreft, Arne Scheffer)
       </para>

       <para>
        Details include <literal>COLLATE</>, <literal>DESC</>,
        <literal>USING</>, and <literal>NULLS FIRST</><literal>/LAST</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <command>VACUUM</> log the number of pages skipped due to pins
        (Jim Nasby)
       </para>
      </listitem>

      <listitem>
       <para>
        Have <command>TRUNCATE</> properly update the <literal>pg_stat</>*
        tuple counters (Alexander Shulgin)
       </para>
      </listitem>

       </itemizedlist>

       <sect4>
        <title><xref linkend="SQL-REINDEX"></title>

        <itemizedlist>

      <listitem>
       <para>
        Allow <command>REINDEX</> to reindex an entire schema using the
        <literal>SCHEMA</> option (Sawada Masahiko)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <literal>VERBOSE</> option to <command>REINDEX</> (Fujii Masao)
       </para>
      </listitem>

      <listitem>
       <para>
        Prevent <command>REINDEX DATABASE</> and <command>SCHEMA</>
        from outputting object names, unless <literal>VERBOSE</> is used
        (Simon Riggs)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove obsolete <literal>FORCE</> option from <command>REINDEX</>
        (Fujii Masao)
       </para>
      </listitem>

      </itemizedlist>

     </sect4>
   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Add row-level security control (Craig Ringer, KaiGai Kohei,
        Adam Brightwell, Dean Rasheed, Stephen Frost)
       </para>

       <para>
        This controls viewing and adding/modifying rows via new commands
        <command>CREATE</>/<command>ALTER</>/<command>DROP POLICY</>
        and <command>ALTER TABLE ... ENABLE/DISABLE ROW SECURITY</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow control of table <acronym>WAL</> logging after table
        creation with <command>ALTER TABLE .. SET LOGGED / UNLOGGED</>
        (Fabr&iacute;zio de Royes Mello)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <literal>IF NOT EXISTS</> clause to <command>CREATE TABLE
        AS</>, <command>CREATE INDEX</>, <command>CREATE SEQUENCE</>,
        and <command>CREATE MATERIALIZED VIEW</> (Fabr&iacute;zio de
        Royes Mello)
       </para>
      </listitem>

      <listitem>
       <para>
        Add support for <literal>IF EXISTS</> to <command>ALTER TABLE
        ... RENAME CONSTRAINT</> (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <literal>CURRENT</><literal>/SESSION_USER</> to specify the
        current user in certain (Kyotaro Horiguchi, &Aacute;lvaro Herrera)
       </para>

       <para>
        Commands include <command>ALTER USER</>, <command>ALTER
        GROUP</>, <command>ALTER ROLE</>, <command>GRANT</>, and various
        <command>ALTER OBJECT / OWNER TO</> commands.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow comments on domain constraints (&Aacute;lvaro Herrera)
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce lock levels of some create and alter trigger and foreign
        key commands (Simon Riggs, Andreas Karlsson)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <command>LOCK TABLE .. ROW EXCLUSIVE MODE</> for those with
        <command>INSERT</> privileges (Stephen Frost)
       </para>

       <para>
        Previously only <command>UPDATE</>, <command>DELETE</>, and
        <command>TRUNCATE</> privileges allowed this.
       </para>
      </listitem>

      <listitem>
       <para>
        Apply table and domain <literal>CHECK</> constraints in name order
        (Tom Lane)
       </para>

       <para>
        The previous order was indeterminate.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <command>CREATE</>/<command>ALTER DATABASE</> to manipulate
        <structname>datistemplate</> and <structname>datallowconn</>
        (Vik Fearing)
       </para>

       <para>
        This allows these database settings to be changed more easily
        than modifying the <structname>pg_database</> system table.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <command>CREATE TABLE AS</> and <command>REFRESH</> return
        an <type>OID</> (&Aacute;lvaro Herrera)
       </para>

       <para>
        RETURN WHERE
       </para>
      </listitem>

     </itemizedlist>

     <sect4>
      <title><xref linkend="SQL-CREATEFOREIGNDATAWRAPPER"></title>

      <itemizedlist>

      <listitem>
       <para>
        Add support for <command>IMPORT FOREIGN SCHEMA</> (Ronan Dunklau,
        Michael Paquier, Tom Lane)
       </para>

       <para>
        This allows the creation of local foreign tables definitions
        that match the remote table structure.  Currently, only the
        <application>postgres_fdw</> foreign data wrapper supports this
        feature.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow foreign tables to participate in inheritance (Shigeru Hanada,
        Etsuro Fujita)
       </para>

       <para>
        This also allows foreign tables to mark check constraints as not
        valid, and to set storage and <type>OID</> characteristics.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <literal>CHECK</> constraints to be placed on foreign tables
        (Shigeru Hanada, Etsuro Fujita)
       </para>

       <para>
        These checks are assumed to be enforced on the remote server,
        and are not checked locally.  However, they are considered for
        optimization and constraint-exclusion checking.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow foreign data wrappers and custom scans to implement join
        pushdown (KaiGai Kohei)
       </para>
      </listitem>

     </itemizedlist>

     </sect4>

     <sect4>
      <title><xref linkend="SQL-CREATEEVENTTRIGGER"></title>

      <itemizedlist>

       <listitem>
        <para>
         Add <function>pg_event_trigger_ddl_commands</> set-returning
         function, which returns <acronym>DDL</> activity associated with
         event triggers (&Aacute;lvaro Herrera)
        </para>
       </listitem>

       <listitem>
        <para>
         Allow event triggers on table rewrites caused by <command>ALTER
         TABLE</> (Dimitri Fontaine)
        </para>
       </listitem>

       <listitem>
        <para>
         Add event trigger support for database-level
         <command>COMMENT</>, <command>SECURITY LABEL</>, and
         <command>GRANT</>/<command>REVOKE</> (&Aacute;lvaro Herrera)
        </para>
       </listitem>

       <listitem>
        <para>
         Add columns to the output of
         <function>pg_event_trigger_dropped_objects</> (&Aacute;lvaro
         Herrera)
        </para>

        <para>
         This allows simpler processing of delete operations.
        </para>
       </listitem>

      </itemizedlist>

     </sect4>

   </sect3>

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

    <itemizedlist>

     <listitem>
      <para>
       Allow the <type>XML</> data type to accept empty or all-whitespace
       values (Peter Eisentraut)
      </para>

      <para>
       This is required by the <acronym>SQL</>/<acronym>XML</>
       specification.
      </para>
     </listitem>

     <listitem>
      <para>
       Fix <type>XML</> xpath handling to return namespace declarations
       even if the namespace is in a parent element (Ali Akbar)
      </para>

      <para>
       Previously the namespace was not returned, leading to invalid
       <type>XML</>.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <type>macaddr</> input using the format
       <literal>xxxx-xxxx-xxxx</> (Herwin Weststrate)
      </para>
     </listitem>

     <listitem>
      <para>
       Tighten specification of <type>INTERVAL</> precision specifications
       (Bruce Momjian)
      </para>

      <para>
       Only allow interval precision to be specified after the
       <literal>INTERVAL</> keyword if no units are specified.
      </para>
     </listitem>

     <listitem>
      <para>
       Add selectivity estimators for <type>INET</>/<type>CIDR</> operators
       and improve estimators for text search functions (Emre Hasegeli,
       Tom Lane)
      </para>
     </listitem>

    </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Add <type>JSONB</> functions <function>jsonb_set()</> and
        <function>jsonb_pretty</> (Dmitry Dolgov, Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Add several generator functions for <type>JSONB</> that exist
        for <type>JSON</> (Andrew Dunstan)
       </para>

       <para>
        The functions are <function>to_jsonb()</>,
        <function>jsonb_object()</>, <function>jsonb_build_object()</>,
        <function>jsonb_build_array()</>, <function>jsonb_agg()</>,
        and <function>jsonb_object_agg()</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Reduce casting requirements to/from <type>JSON</> and
        <type>JSONB</> (Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <type>TEXT</>, <type>TEXT</> array, and <type>INTEGER</>
        values to be subtracted from <type>JSONB</> documents (Dmitry
        Dolgov, Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <type>JSONB</> operator || (Dmitry Dolgov, Andrew Dunstan)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <function>json_strip_nulls()</> and
        <function>jsonb_strip_nulls()</> functions to remove <type>JSON</>
        null values from documents (Andrew Dunstan)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <function>generate_series()</> for <type>NUMERIC</> values
        (Plato Malugin)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <function>array_agg()</> and <function>ARRAY()</> to take
        arrays as inputs (Ali Akbar, Tom Lane)
       </para>
      </listitem>

      <listitem>
       <para>
        Add functions <function>array_position()</> and
        <function>array_positions()</> to return subscripts of array values
        (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
       <para>
        Add <type>point</>-to-<type>polygon</> distance operator
        (&lt;-&gt;) (Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow multi-byte characters as escape in <literal>SIMILAR TO</>
        and <literal>SUBSTRING</> (Jeff Davis)
       </para>

       <para>
        Previously, only a single-byte character was allowed as an escape.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <function>width_bucket()</> which supports any sortable data
        type and non-uniform bucket widths (Petr Jelinek)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow =&gt; to specify named parameters in function calls
        (Pavel Stehule)
       </para>

       <para>
        User-defined =&gt; operators have been issuing warnings since
        Postgres 9.0, and were removed in hstore in 9.2.  Previously only
        <literal>:=</> could be used.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <acronym>POSIX</>-compliant rounding for platforms that use
        Postgres-supplied rounding functions (Pedro Gimeno Fortea)
       </para>
      </listitem>

     </itemizedlist>

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

     <itemizedlist>

      <listitem>
       <para>
        Add function <function>pg_get_object_address()</> to return
        <type>OID</>s that uniquely identify an object (&Aacute;lvaro
        Herrera)
       </para>
      </listitem>

      <listitem>
       <para>
        Add function <function>pg_identify_object_as_address()</> to return
        object information based on <type>OID</>s (&Aacute;lvaro Herrera)
       </para>
      </listitem>

      <listitem>
       <para>
        Loosen security checks for viewing <structname>pg_stat_activity</>,
        <function>pg_cancel_backend()</>, and
        <function>pg_terminate_backend</> (Stephen Frost)
       </para>

       <para>
        Now, role membership is sufficient;  previously only the same
        role could perform such operations.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <function>pg_stat_get_snapshot_timestamp()</> to output the
        timestamp of the statistics snapshot (Matt Kelly)
       </para>

       <para>
        This represents the last time the snapshot files was written to
        the file system.
       </para>
      </listitem>

      <listitem>
       <para>
        Add <function>mxid_age()</> to compute multi-xid age (Bruce
        Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Add data type <type>regrole</> that returns the <type>OID</>
        of a role (Kyotaro Horiguchi)
       </para>
      </listitem>

      <listitem>
       <para>
        Add data type <type>regnamespace</> that returns the <type>OID</>
        of a schema (Kyotaro Horiguchi)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Aggregates</title>

     <itemizedlist>

      <listitem>
       <para>
        Add <function>MIN()</>/<function>MAX()</> aggregates for
        <type>INET</>/<type>CIDR</> data types (Haribabu Kommi)
       </para>
      </listitem>

      <listitem>
       <para>
        Use 128-bit integers, where supported, as aggregate accumulators
        (Andreas Karlsson)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

     <listitem>
      <para>
       Improve support for composite types in <application>PL/Python</>
       (Ed Behn, Ronan Dunklau)
      </para>

      <para>
       This allows <application>PL/Python</> functions to return arrays
       of composite types.
      </para>
     </listitem>

     <listitem>
      <para>
       Reduce lossiness of <application>PL/Python</> floating value
       conversions (Marko Kreen)
      </para>
     </listitem>

     <listitem>
      <para>
       Add specification of conversion routines to/from <acronym>SQL</>
       data types to procedural languages data types (Peter Eisentraut)
      </para>

      <para>
       This adds new commands <command>CREATE</>/<command>DROP
       TRANSFORM</>.  This also adds transformations between
       <application>hstore</> and <application>ltree</> to/from
       <application>PL/Perl</> and <application>PL/Python</>.
      </para>
     </listitem>

     </itemizedlist>

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

      <itemizedlist>

     <listitem>
      <para>
       Improve <application>PL/pgSQL</> array performance (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <command>ASSERT</> statement in <application>PL/pgSQL</>
       (Pavel Stehule)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow more <application>PL/pgSQL</> keywords to be used as
       identifiers (Tom Lane)
      </para>
     </listitem>

    </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

     <listitem>
      <para>
       Move <application>pg_archivecleanup</>,
       <application>pg_test_fsync</>, <application>pg_test_timing</>,
       and <application>pg_xlogdump</> from <filename>contrib</> to
       <filename>src/bin</> (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <application>pg_receivexlog</> to manage physical replication
       slots (Michael Paquier)
      </para>

      <para>
       This is controlled via new <option>--create-slot</> and
       <option>--drop-slot</> options.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow the <application>pg_receivexlog</> to synchronously flush
       <acronym>WAL</> to storage using <option>--synchronous</> (Furuya
       Osamu, Fujii Masao)
      </para>

      <para>
       Without this, <acronym>WAL</> files are fsynced only on close.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <command>vacuumdb</> to vacuum in parallel using
       <option>--jobs</> (Dilip Kumar)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <option>--verbose</> option to <application>reindexdb</>
       (Sawada Masahiko)
      </para>
     </listitem>

     <listitem>
      <para>
       Have <application>pg_basebackup</> use a tablespace mapping
       file with the <application>tar</> format, to handle file paths
       of 100+ characters in length and sybolic links on <systemitem
       class="osname">MS Windows</> (Amit Kapila)
      </para>

      <para>
       This change prevents <application>pg_basebackup</> from backing
       up pre-9.5 servers.
      </para>
     </listitem>

    </itemizedlist>

     <sect4>
      <title><xref linkend="APP-PSQL"></title>

      <itemizedlist>

       <listitem>
        <para>
         Allow <application>psql</> to produce AsciiDoc output (Szymon Guz)
        </para>
       </listitem>

       <listitem>
        <para>
         Add <literal>errors</> mode to <application>psql</>'s
         <varname>ECHO</> variable to display only failed commands
         (Pavel Stehule)
        </para>

        <para>
         This can also be enabled with the <application>psql</>
         <option>-b</> option.
        </para>
       </listitem>

       <listitem>
        <para>
         Allow column, header, and border control to <application>psql</>'s
         Unicode style (Pavel Stehule)
        </para>

        <para>
         Single or double output is supported;  the default is
         <literal>single</>.
        </para>
       </listitem>

       <listitem>
        <para>
         Add <application>psql</> <envar>PROMPT</> variable option
         (<literal>%l</>) to display the multi-line statement line number
         (Sawada Masahiko)
        </para>
       </listitem>

       <listitem>
        <para>
         Add <application>psql</> setting <varname>pager_min_lines</>
         setting to control pager invocation (Andrew Dunstan)
        </para>
       </listitem>

       <listitem>
        <para>
         Improve <application>psql</> line counting used when deciding
         to invoke the pager (Andrew Dunstan)
        </para>
       </listitem>

       <listitem>
        <para>
         Add <application>psql</> tab completion when setting the
         <varname>search_path</> variable (Jeff Janes)
        </para>

        <para>
         Currently only the first schema can be tab-completed.
        </para>
       </listitem>

       <listitem>
        <para>
         Improve <application>psql</> tab-completion for triggers and rules
         (Andreas Karlsson)
        </para>
       </listitem>

      </itemizedlist>

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

      <itemizedlist>

       <listitem>
        <para>
         Add <application>psql</> <command>\?</> help sections
         <literal>variables</> and <literal>options</> (Pavel Stehule)
        </para>

        <para>
         <literal>variables</> outputs <application>psql</> variables
         and <literal>options</> shows command-line options.
         <command>\? commands</> is the default output. This help
         information can also be output via <literal>--help=section</>.
        </para>
       </listitem>

       <listitem>
        <para>
         Show tablespace size in <application>psql</>'s <literal>\db+</>
         (Fabr&iacute;zio de Royes Mello)
        </para>
       </listitem>

       <listitem>
        <para>
         Show data type owners in <application>psql</>'s <literal>\dT+</>
         (Magnus Hagander)
        </para>
       </listitem>

       <listitem>
        <para>
         Allow <application>psql</> <command>\watch</> to output
         <command>\timing</> information (Fujii Masao)
        </para>

        <para>
         Also prevent <option>--echo-hidden</> from echoing
         <command>\watch</> queries.
        </para>
       </listitem>

       <listitem>
        <para>
         Allow <application>psql</>'s <literal>\sf</> and <literal>\ef</>
         to honor <envar>ECHO_HIDDEN</> (Andrew Dunstan)
        </para>
       </listitem>

       <listitem>
        <para>
         Improve <application>psql</> tab completion for <command>\set</>,
         <command>\unset</>, and <literal>:variable</> names (Pavel
         Stehule)
        </para>
       </listitem>

       <listitem>
        <para>
         Allow tab completion of <application>psql</> <literal>\c</>
         role names (Ian Barwick)
        </para>
       </listitem>

      </itemizedlist>

     </sect5>

    </sect4>

    <sect4>
     <title><xref linkend="APP-PGDUMP"></title>

     <itemizedlist>

      <listitem>
       <para>
        Allow <application>pg_dump</> to share a snapshot taken by another
        session using <option>--snapshot</> (Simon Riggs, Michael Paquier)
       </para>

       <para>
        The remote snapshot must have been exported by
        <function>pg_export_snapshot()</> or been defined as a
        logical replication slot.  This can be used by parallel
        <application>pg_dump</> to use a consistent snapshot across
        <application>pg_dump</> processes.
       </para>
      </listitem>

      <listitem>
       <para>
        Always have <application>pg_dump</> print server and
        <application>pg_dump</> versions (Jing Wang)
       </para>

       <para>
        Previously, version information was only printed in
        <option>--verbose</> mode.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><xref linkend="app-pg-ctl"></title>

     <itemizedlist>

      <listitem>
       <para>
        Change <application>pg_ctl</> default shutdown mode from
        <literal>smart</> to <literal>fast</> (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow multiple <application>pg_ctl</> <option>-o</> options to
        be appended (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow control of <application>pg_ctl</>'s event source logging
        on <systemitem class="osname">MS Windows</> (MauMau)
       </para>

       <para>
        This only controls <application>pg_ctl</>, not the server, which
        has separate settings in <filename>postgresql.conf</>.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title><xref linkend="pgupgrade"></title>

     <itemizedlist>

      <listitem>
       <para>
        Move <application>pg_upgrade</> from <filename>contrib</> to
        <filename>src/bin</> (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow multiple <application>pg_upgrade</>
        <option>-o</>/<option>-O</> options to be appended (Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve database collation comparisons in
        <application>pg_upgrade</> (Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
       <para>
        Document the use of <application>rsync</> for standby server
        upgrades using <application>pg_upgrade</> (Stephen Frost,
        Bruce Momjian)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <application>pg_upgrade</> support for 8.3 old clusters
        (Bruce Momjian)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

     <itemizedlist>

      <listitem>
       <para>
        Simplify <acronym>WAL</> record format (Heikki Linnakangas)
       </para>

       <para>
        This allows external tools to more easily process <acronym>WAL</>
        files.
       </para>
      </listitem>

      <listitem>
       <para>
        Add basic atomics <acronym>API</> support (Andres Freund, Oskari
        Saarenmaa)
       </para>
      </listitem>

      <listitem>
       <para>
        Add native compiler and memory barriers for <productname>Solaris
        Studio</> (Oskari Saarenmaa)
       </para>

       <para>
        IS THIS PART OF ATOMICS?
       </para>
      </listitem>

      <listitem>
       <para>
        Allow custom path and scan methods (KaiGai Kohei, Tom Lane)
       </para>

       <para>
        This allows extensions greater control over the optimizer and
        executor.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow foreign data wrappers to do post-filter locking (Etsuro
        Fujita)
       </para>
      </listitem>

      <listitem>
       <para>
        Improve parallel execution infrastructure (Robert Haas, Amit
        Kapila, Noah Misch, Rushabh Lathia, Jeevan Chalke)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <productname>Alpha</> (<acronym>CPU</>) and <systemitem
        class="osname">Tru64</> (OS) ports (Andres Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Remove swap-byte-based spinlock implementation for
        <acronym>ARM</>v5 and earlier <acronym>CPU</>s (Robert Haas)
       </para>

       <para>
        <acronym>ARM</>v5's weak memory ordering made this locking
        implementation unsafe.  Spinlock support is still possible on
        newer gcc implementations with atomics support.
       </para>
      </listitem>

      <listitem>
       <para>
        Generate an error when excessively long (100+ character) file
        paths are written to tar files (Peter Eisentraut)
       </para>

       <para>
        Tar does not support such overly-long paths.
       </para>
      </listitem>

      <listitem>
       <para>
        Change columns <structname>pg_seclabel</>.<structname>provider</>
        and <structname>pg_shseclabel</>.<structname>provider</> to
        <type>TEXT</> (Tom Lane)
       </para>

       <para>
        This allows these columns to store 64+ characters.
       </para>
      </listitem>

     </itemizedlist>

    <sect4>
     <title>MS Windows</title>

     <itemizedlist>

      <listitem>
       <para>
        Allow higher-precision timestamp resolution on <systemitem
        class="osname">Windows 8</> or <systemitem class="osname">Windows
        Server 2012</> and later Windows systems (Craig Ringer)
       </para>
      </listitem>

      <listitem>
       <para>
        Install shared libraries to <filename>bin</> in <systemitem
        class="osname">MS Windows</> (Peter Eisentraut, Michael Paquier)
       </para>
      </listitem>

      <listitem>
       <para>
        Install <filename>src/test/modules</> together with
        <filename>contrib</> on <productname>MSVC</> builds (Michael
        Paquier)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow configure's <option>--with-extra-version</> to be honored
        by the <productname>MSVC</> build (Michael Paquier)
       </para>
      </listitem>

      <listitem>
       <para>
        Pass <envar>PGFILEDESC</> into <productname>MSVC</> contrib builds
        (Michael Paquier)
       </para>
      </listitem>

      <listitem>
       <para>
        Add icons to all <productname>MSVC</>-built binaries (Noah Misch)
       </para>

       <para>
        MinGW already had such icons.
       </para>
      </listitem>

      <listitem>
       <para>
        Add optional-argument support to the internal
        <function>getopt_long()</> implementation (Michael Paquier,
        Andres Freund)
       </para>

       <para>
        This is used by the <productname>MSVC</> build.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

     <listitem>
      <para>
       Add <application>pg_rewind</>, which allows re-synchronizing a
       master server after failback (Heikki Linnakangas)
      </para>
     </listitem>

     <listitem>
      <para>
       Add statistics for minimum, maximum, mean, and standard deviation
       times to <application>pg_stat_statements</> (Mitsumasa Kondo,
       Andrew Dunstan)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <application>pgcrypto</> function
       <function>pgp_armor_headers()</> to extract <productname>PGP</>
       armor headers (Marko Tiikkaja, Heikki Linnakangas)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow empty replacement strings in <application>unaccent</>
       (Mohammad Alhashash)
      </para>

      <para>
       This is useful in languages where diacritic signs are represented
       as separate characters.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow multi-character source strings in <application>unaccent</>
       (Tom Lane)
      </para>

      <para>
       This could be useful in languages where diacritic signs are
       represented as separate characters.  It also allows more complex
       unaccent dictionaries.
      </para>
     </listitem>

     <listitem>
      <para>
       Add <filename>contrib</> modules <application>tsm_system_rows</>
       and <application>tsm_system_time</> to allow additional table
       sampling methods (Petr Jelinek)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <application>pg_xlogdump</> option <option>--stats</> to
       display summary statistics (Abhijit Menon-Sen)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <acronym>GIN</> index inspection functions to
       <application>pageinspect</> (Heikki Linnakangas, Peter Geoghegan,
       Michael Paquier)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <application>pgstattuple</> to report approximate answers
       with less overhead using <function>pgstattuple_approx()</>
       (Abhijit Menon-Sen)
      </para>
     </listitem>

     <listitem>
      <para>
       Move <application>pg_upgrade_support</> code into backend and
       remove the module (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Move <application>dummy_seclabel</>, <application>test_shm_mq</>,
       <application>test_parser</>, and <application>worker_spi</>
       from <filename>contrib</> to <filename>src/test/modules</>
       (&Aacute;lvaro Herrera)
      </para>
     </listitem>

    </itemizedlist>

    <sect4>
     <title><xref linkend="pgbench"></title>

     <itemizedlist>

      <listitem>
       <para>
        Move pgbench from <filename>contrib</> to <filename>src/bin</>
        (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow counting of pgbench transactions that take over a specified
        amount of time (Fabien Coelho)
       </para>

       <para>
        This is controlled by new <option>--latency-limit</> option.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow pgbench to generate Gaussian/exponential distributions
        using <command>\setrandom</> (Kondo Mitsumasa, Fabien Coelho)
       </para>
      </listitem>

      <listitem>
       <para>
        Add information about buffer pins to <application>pg_buffercache</>
        display (Andres Freund)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>pgbench</>'s <command>\set</> command to handle
        multi-operator expressions (Robert Haas, Fabien Coelho)
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

  </sect2>

 </sect1>