<!-- doc/src/sgml/release-11.sgml -->
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 <sect1 id="release-11">
  <title>Release 11</title>

  <formalpara>
   <title>Release date:</title>
   <para>2018-10-18</para>
  </formalpara>

  <sect2>
   <title>Overview</title>

   <para>
    Major enhancements in <productname>PostgreSQL</productname> 11 include:
   </para>

   <!-- Items in this list summarize one or more items below -->

   <itemizedlist>

    <listitem>
     <para>
      Improvements to partitioning functionality, including:
      <itemizedlist>
       <listitem>
        <para>
         Add support for partitioning by a hash key
        </para>
       </listitem>
       <listitem>
        <para>
         Add support for <literal>PRIMARY KEY</literal>, <literal>FOREIGN
         KEY</literal>, indexes, and triggers on partitioned tables
        </para>
       </listitem>
       <listitem>
        <para>
         Allow creation of a <quote>default</quote> partition for storing
         data that does not match any of the remaining partitions
        </para>
       </listitem>
       <listitem>
        <para>
         <command>UPDATE</command> statements that change a partition key
         column now cause affected rows to be moved to the appropriate
         partitions
        </para>
       </listitem>
       <listitem>
        <para>
         Improve <command>SELECT</command> performance through enhanced
         partition elimination strategies during query planning and execution
        </para>
       </listitem>
      </itemizedlist>
     </para>
    </listitem>

    <listitem>
     <para>
      Improvements to parallelism, including:
      <itemizedlist>
       <listitem>
        <para>
         <command>CREATE INDEX</command> can now use parallel processing
         while building a B-tree index
        </para>
       </listitem>
       <listitem>
        <para>
         Parallelization is now possible in <command>CREATE TABLE
         ... AS</command>,
         <command>CREATE MATERIALIZED VIEW</command>, and certain
         queries using <literal>UNION</literal>
        </para>
       </listitem>
       <listitem>
        <para>
         Parallelized hash joins and parallelized sequential scans now
         perform better
        </para>
       </listitem>
      </itemizedlist>
     </para>
    </listitem>

    <listitem>
     <para>
      SQL stored procedures that support embedded transactions
     </para>
    </listitem>

    <listitem>
     <para>
      Optional Just-in-Time (JIT) compilation for some SQL code, speeding
      evaluation of expressions
     </para>
    </listitem>

    <listitem>
     <para>
      Window functions now support all framing options shown in the SQL:2011
      standard, including <literal>RANGE <replaceable>distance</replaceable>
      PRECEDING/FOLLOWING</literal>, <literal>GROUPS</literal> mode, and
      frame exclusion options
     </para>
    </listitem>

    <listitem>
     <para>
      Covering indexes can now be created, using the
      <literal>INCLUDE</literal> clause of <command>CREATE INDEX</command>
     </para>
    </listitem>

    <listitem>
     <para>
      Many other useful performance improvements, including the ability to
      avoid a table rewrite for <command>ALTER TABLE ... ADD COLUMN</command>
      with a non-null column default
     </para>
    </listitem>

   </itemizedlist>

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

  </sect2>

  <sect2>

  <title>Migration to Version 11</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 11 contains a number of changes that may affect compatibility
    with previous releases.  Observe the following incompatibilities:
   </para>

   <itemizedlist>

    <listitem>
<!--
2018-01-22 [b3f840120] Move handling of database properties from pg_dumpall int
2018-01-23 [160a4f62e] In pg_dump, force reconnection after issuing ALTER DATAB
2018-01-25 [0d4e6ed30] Clean up some aspects of pg_dump/pg_restore item-selecti
-->

       <para>
        Make <link
        linkend="app-pgdump"><application>pg_dump</application></link>
        dump the properties of a database, not just its contents
        (Haribabu Kommi)
       </para>

       <para>
        Previously, attributes of the database itself, such as database-level
        <command>GRANT</command>/<command>REVOKE</command> permissions and
        <command>ALTER DATABASE SET</command> variable settings, were only
        dumped by <link linkend="app-pg-dumpall"><application>pg_dumpall</application></link>.
        Now <command>pg_dump --create</command> and
        <command>pg_restore --create</command> will restore these database
        properties in addition to the objects within the
        database.  <command>pg_dumpall -g</command> now only dumps role-
        and tablespace-related attributes.
        <application>pg_dumpall</application>'s complete output (without
        <option>-g</option>) is unchanged.
       </para>

       <para>
        <application>pg_dump</application> and
        <application>pg_restore</application>, without
        <option>--create</option>, no longer dump/restore database-level
        comments and security labels; those are now treated as properties of
        the database.
       </para>

       <para>
        <application>pg_dumpall</application>'s output script will now always
        create databases with their original locale and encoding, and hence
        will fail if the locale or encoding name is unknown to the
        destination system.  Previously, <command>CREATE DATABASE</command>
        would be emitted without these specifications if the database locale
        and encoding matched the old cluster's defaults.
       </para>

       <para>
        <command>pg_dumpall --clean</command> now restores the original
        locale and encoding settings of the <literal>postgres</literal>
        and <literal>template1</literal> databases, as well as those of
        user-created databases.
       </para>
      </listitem>

      <listitem>
<!--
2018-06-18 [b97a3465d] Consider syntactic form when disambiguating function vs
2018-06-18 [45e98ee73] Remove obsolete prohibition on function name matching a
-->

       <para>
        Consider syntactic form when disambiguating function versus column
        references (Tom Lane)
       </para>

       <para>
        When <replaceable>x</replaceable> is a table name or composite
        column, <productname>PostgreSQL</productname> has traditionally
        considered the syntactic
        forms <literal><replaceable>f</replaceable>(<replaceable>x</replaceable>)</literal>
        and <literal><replaceable>x</replaceable>.<replaceable>f</replaceable></literal>
        to be equivalent, allowing tricks such as writing a function and
        then using it as though it were a computed-on-demand column.
        However, if both interpretations are feasible, the column
        interpretation was always chosen, leading to surprising results if
        the user intended the function interpretation.  Now, if there is
        ambiguity, the interpretation that matches the syntactic form is
        chosen.
       </para>
      </listitem>

      <listitem>
<!--
2018-09-04 [fb466d7b5] Fully enforce uniqueness of constraint names.
-->
       <para>
        Fully enforce uniqueness of table and domain constraint names
        (Tom Lane)
       </para>

       <para>
        <productname>PostgreSQL</productname> expects the names of a table's
        constraints to be distinct, and likewise for the names of a domain's
        constraints.  However, there was not rigid enforcement of this, and
        previously there were corner cases where duplicate names could be
        created.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-29 [61b200e2f] Avoid wrong results for power() with NaN input on some p
2018-04-29 [6bdf1303b] Avoid wrong results for power() with NaN input on more p
2018-05-17 [d1fc750b5] Make numeric power() handle NaNs according to the modern
-->

       <para>
        Make <function>power(numeric, numeric)</function>
        and <function>power(float8, float8)</function>
        handle <literal>NaN</literal> inputs according to the POSIX standard
        (Tom Lane, Dang Minh Huong)
       </para>

       <para>
        POSIX says that <literal>NaN ^ 0 = 1</literal> and <literal>1 ^ NaN
        = 1</literal>, but all other cases with <literal>NaN</literal>
        input(s) should return <literal>NaN</literal>.
        <function>power(numeric, numeric)</function> just
        returned <literal>NaN</literal> in all such cases; now it honors the
        two exceptions.  <function>power(float8, float8)</function> followed
        the standard if the C library does; but on some old Unix platforms
        the library doesn't, and there were also problems on some versions
        of Windows.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-17 [e87d4965b] Prevent to_number() from losing data when template doesn
-->

       <para>
        Prevent <link
        linkend="functions-formatting-numeric-table"><function>to_number()</function></link>
        from consuming characters when the template separator does not
        match (Oliver Ford)
       </para>

       <para>
        Specifically, <command>SELECT to_number('1234', '9,999')</command>
        used to return <literal>134</literal>.  It will now
        return <literal>1234</literal>.  <literal>L</literal> and
        <literal>TH</literal> now only consume characters that are not
        digits, positive/negative signs, decimal points, or commas.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-18 [976a1a48f] Improve to_date/to_number/to_timestamp behavior with mul
-->

       <para>
        Fix <link
        linkend="functions-formatting"><function>to_date()</function></link>,
        <function>to_number()</function>, and
        <function>to_timestamp()</function> to skip a character for each
        template character (Tom Lane)
       </para>

       <para>
        Previously, they skipped one <emphasis>byte</emphasis> for each byte
        of template character, resulting in strange behavior if either string
        contained multibyte characters.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-18 [63ca86318] Fix quoted-substring handling in format parsing for to_c
-->

       <para>
        Adjust the handling of backslashes inside double-quotes in
        template strings for <function>to_char()</function>,
        <function>to_number()</function>, and
        <function>to_timestamp()</function>.
       </para>

       <para>
        Such a backslash now escapes the character after it, particularly
        a double-quote or another backslash.
       </para>
      </listitem>

      <listitem>
<!--
2018-06-21 [e474c2b7e] Set correct context for XPath evaluation
-->

       <para>
        Correctly handle relative path expressions
        in <function>xmltable()</function>, <function>xpath()</function>,
        and other XML-handling functions (Markus Winand)
       </para>

       <para>
        Per the SQL standard, relative paths start from the document node of
        the XML input document, not the root node as these functions
        previously did.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-18 [f8e5f156b] Rearm statement_timeout after each executed query.

-->

       <para>
        In the <link linkend="protocol-query-concepts">extended query
        protocol</link>,
        make <link linkend="guc-statement-timeout"><varname>statement_timeout</varname></link>
        apply to each Execute message separately, not to all commands before
        Sync (Tatsuo Ishii, Andres Freund)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-14 [f66e8bf87] Remove pg_class.relhaspkey
-->

       <para>
        Remove the <structfield>relhaspkey</structfield> column from system
        catalog <structname>pg_class</structname> (Peter Eisentraut)
       </para>

       <para>
        Applications needing to check for a primary key should consult
        <structname>pg_index</structname>.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-02 [fd1a421fe] Add prokind column, replacing proisagg and proiswindow
-->

       <para>
        Replace system catalog <structname>pg_proc</structname>'s
        <structfield>proisagg</structfield> and
        <structfield>proiswindow</structfield> columns with
        <structfield>prokind</structfield> (Peter Eisentraut)
       </para>

       <para>
        This new column more clearly distinguishes functions, procedures,
        aggregates, and window functions.
       </para>
      </listitem>

      <listitem>
<!--
2017-08-16 [9b5140fb5] Correct representation of foreign tables in information
-->

       <para>
        Correct information schema column <link
        linkend="infoschema-tables"><structname>tables</structname>.<structfield>table_type</structfield></link>
        to return <literal>FOREIGN</literal> instead of <literal>FOREIGN
        TABLE</literal> (Peter Eisentraut)
       </para>

       <para>
        This new output matches the SQL standard.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-20 [be87b70b6] Sync process names between ps and pg_stat_activity
-->

       <para>
        Change the ps process display
        labels for background workers to match the <link
        linkend="pg-stat-activity-view"><structname>pg_stat_activity</structname>.<structfield>backend_type</structfield></link>
        labels (Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
<!--
2017-11-09 [ae20b23a9] Refactor permissions checks for large objects.
2017-11-14 [6d776522d] Document changes in large-object privilege checking.
-->

       <para>
        Cause large object permission checks
        to happen during large object open, <link
        linkend="lo-open"><function>lo_open()</function></link>, not
        when a read or write is attempted (Tom Lane, Michael Paquier)
       </para>

       <para>
        If write access is requested and not available, an error will now be
        thrown even if the large object is never written to.
       </para>
      </listitem>

      <listitem>
<!--
2018-08-09 [87330e21c] Restrict access to reindex of shared catalogs for non-pr
-->
       <para>
        Prevent non-superusers from reindexing shared catalogs
        (Michael Paquier, Robert Haas)
       </para>

       <para>
        Previously, database owners were also allowed to do this, but
        now it is considered outside the bounds of their privileges.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-06 [11523e860] Support new default roles with adminpack
-->

       <para>
        Remove deprecated <link
        linkend="adminpack"><filename>adminpack</filename></link> functions
        <function>pg_file_read()</function>,
        <function>pg_file_length()</function>, and
        <function>pg_logfile_rotate()</function> (Stephen Frost)
       </para>

       <para>
        Equivalent functionality is now present in the core backend.
        Existing <filename>adminpack</filename> installs will continue to have
        access to these functions until they are updated via <command>ALTER
        EXTENSION ... UPDATE</command>.
       </para>
      </listitem>

      <listitem>
<!--
2018-01-26 [fb8697b31] Avoid unnecessary use of pg_strcasecmp for already-downc
-->

       <para>
        Honor the capitalization of double-quoted command options
        (Daniel Gustafsson)
       </para>

       <para>
        Previously, option names in certain SQL commands were forcibly
        lower-cased even if entered with double quotes; thus for example
        <literal>"FillFactor"</literal> would be accepted as an index storage
        option, though properly its name is lower-case.  Such cases will now
        generate an error.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-29 [8b304b8b7] Remove replacement selection sort.
-->

       <para>
        Remove server parameter <varname>replacement_sort_tuples</varname>
        (Peter Geoghegan)
       </para>

       <para>
        Replacement sorts were determined to be no longer useful.
       </para>

      </listitem>

      <listitem>
<!--
2018-01-26 [4971d2a32] Remove the obsolete WITH clause of CREATE FUNCTION.
-->

       <para>
        Remove <literal>WITH</literal> clause in <link
        linkend="sql-createfunction"><command>CREATE
        FUNCTION</command></link> (Michael Paquier)
       </para>

       <para>
        <productname>PostgreSQL</productname> has long supported a more
        standard-compliant syntax for this capability.
       </para>
      </listitem>

   </itemizedlist>

  </sect2>

  <sect2>
   <title>Changes</title>

   <para>
    Below you will find a detailed account of the changes between
    <productname>PostgreSQL</productname> 11 and the previous major
    release.
   </para>

   <sect3>
    <title>Server</title>

    <sect4>
     <title>Partitioning</title>

     <itemizedlist>

      <listitem>
<!--
2017-11-09 [1aba8e651] Add hash partitioning.
-->

       <para>
        Allow the creation of partitions based on hashing a key column
        (Amul Sul)
       </para>
      </listitem>

      <listitem>
<!--
2018-01-19 [8b08f7d48] Local partitioned indexes
2018-02-19 [eb7ed3f30] Allow UNIQUE indexes on partitioned tables
2018-03-26 [555ee77a9] Handle INSERT .. ON CONFLICT with partitioned tables
-->

       <para>
        Support indexes on partitioned tables (&Aacute;lvaro Herrera,
        Amit Langote)
       </para>

       <para>
        An <quote>index</quote> on a partitioned table is not a physical
        index across the whole partitioned table, but rather a template for
        automatically creating similar indexes on each partition of the
        table.
       </para>

       <para>
        If the partition key is part of the index's column set, a
        partitioned index may be declared <literal>UNIQUE</literal>.
        It will represent a valid uniqueness constraint across the whole
        partitioned table, even though each physical index only enforces
        uniqueness within its own partition.
       </para>

       <para>
        The new command <link linkend="sql-alterindex"><command>ALTER
        INDEX ATTACH PARTITION</command></link> causes an existing index on
        a partition to be associated with a matching index template for its
        partitioned table.  This provides flexibility in setting up a new
        partitioned index for an existing partitioned table.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-04 [3de241dba] Foreign keys on partitioned tables
-->

       <para>
        Allow foreign keys on partitioned tables (&Aacute;lvaro Herrera)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-23 [86f575948] Allow FOR EACH ROW triggers on partitioned tables
-->

       <para>
        Allow <literal>FOR EACH ROW</literal> triggers on partitioned
        tables (&Aacute;lvaro Herrera)
       </para>

       <para>
        Creation of a trigger on a partitioned table automatically creates
        triggers on all existing and future partitions.
        This also allows deferred unique constraints on partitioned tables.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-08 [6f6b99d13] Allow a partitioned table to have a default partition.
2018-04-11 [72cf7f310] Fix ALTER TABLE .. ATTACH PARTITION ... DEFAULT
-->

       <para>
        Allow partitioned tables to have a default partition (Jeevan Ladhe,
        Beena Emerson, Ashutosh Bapat, Rahila Syed, Robert Haas)
       </para>

       <para>
        The default partition will store rows that don't match any of the
        other defined partitions, and is searched accordingly.
       </para>
      </listitem>

      <listitem>
<!--
2018-01-19 [2f1784410] Allow UPDATE to move rows between partitions.
-->

       <para>
        <command>UPDATE</command> statements that change a partition key
        column now cause affected rows to be moved to the appropriate
        partitions (Amit Khandekar)
       </para>
      </listitem>

      <listitem>
<!--
2018-04-06 [3d956d956] Allow insert and update tuple routing and COPY for forei
-->

       <para>
        Allow <command>INSERT</command>, <command>UPDATE</command>, and
        <command>COPY</command> on partitioned tables to properly route
        rows to foreign partitions (Etsuro Fujita, Amit Langote)
       </para>

       <para>
        This is supported by <filename>postgres_fdw</filename>
        foreign tables.
       </para>
      </listitem>

      <listitem>
<!--
2018-02-02 [9aef17316] Refactor code for partition bound searching
2018-02-23 [f724022d0] Revise API for partition bound search functions.
2018-04-06 [9fdb675fc] Faster partition pruning
2018-04-23 [055fb8d33] Add GUC enable_partition_pruning
-->

       <para>
        Allow faster partition elimination during query processing (Amit
        Langote, David Rowley, Dilip Kumar)
       </para>

       <para>
        This speeds access to partitioned tables with many partitions.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-07 [499be013d] Support partition pruning at execution time
-->

       <para>
        Allow partition elimination during query execution (David Rowley,
        Beena Emerson)
       </para>

       <para>
        Previously, partition elimination only happened at planning
        time, meaning many joins and prepared queries could not use
        partition elimination.
       </para>
      </listitem>

      <listitem>
<!--
2017-08-15 [e139f1953] Assorted preparatory refactoring for partition-wise join
2017-10-06 [f49842d1e] Basic partition-wise join functionality.
2018-02-16 [2fb1abaeb] Rename enable_partition_wise_join to enable_partitionwis
-->

       <para>
        In an equality join between partitioned tables, allow matching
        partitions to be joined directly (Ashutosh Bapat)
       </para>

       <para>
        This feature is disabled by default
        but can be enabled by changing <link
        linkend="guc-enable-partitionwise-join"><varname>enable_partitionwise_join</varname></link>.
       </para>
      </listitem>

      <listitem>
<!--
2018-01-26 [9fd8b7d63] Factor some code out of create_grouping_paths.
2018-03-22 [e2f1eb0ee] Implement partition-wise grouping/aggregation.
-->

       <para>
        Allow aggregate functions on partitioned tables to be evaluated
        separately for each partition, subsequently merging the results
        (Jeevan Chalke, Ashutosh Bapat, Robert Haas)
       </para>

       <para>
        This feature is disabled by default
        but can be enabled by changing <link
        linkend="guc-enable-partitionwise-aggregate"><varname>enable_partitionwise_aggregate</varname></link>.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-02 [7e0d64c7a] postgres_fdw: Push down partition-wise aggregation.
-->

       <para>
        Allow <link
        linkend="postgres-fdw"><filename>postgres_fdw</filename></link>
        to push down aggregates to foreign tables that are partitions
        (Jeevan Chalke)
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Parallel Queries</title>

     <itemizedlist>

      <listitem>
<!--
2018-02-02 [9da0cc352] Support parallel btree index builds.
-->

       <para>
        Allow parallel building of a btree index (Peter Geoghegan,
        Rushabh Lathia, Heikki Linnakangas)
       </para>
      </listitem>

      <listitem>
<!--
2017-12-21 [180428404] Add parallel-aware hash joins.
-->

       <para>
        Allow hash joins to be performed in parallel using a shared hash
        table (Thomas Munro)
       </para>
      </listitem>

      <listitem>
<!--
2017-12-05 [ab7271677] Support Parallel Append plan nodes.
2018-03-22 [88ba0ae2a] Consider Parallel Append of partial paths for UNION [ALL
-->

       <para>
        Allow <literal>UNION</literal> to run each
        <command>SELECT</command> in parallel if the individual
        <command>SELECT</command>s cannot be parallelized (Amit Khandekar,
        Robert Haas, Amul Sul)
       </para>
      </listitem>

      <listitem>
<!--
same commits as above
2017-12-05 [ab7271677] Support Parallel Append plan nodes.
2018-03-22 [88ba0ae2a] Consider Parallel Append of partial paths for UNION [ALL
-->

       <para>
        Allow partition scans to more efficiently use parallel workers
        (Amit Khandekar, Robert Haas, Amul Sul)
       </para>
      </listitem>

      <listitem>
<!--
2017-08-29 [3452dc524] Push tuple limits through Gather and Gather Merge.
-->

       <para>
        Allow <literal>LIMIT</literal> to be passed to parallel workers
        (Robert Haas, Tom Lane)
       </para>

       <para>
        This allows workers to reduce returned results and use targeted
        index scans.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-16 [e89a71fb4] Pass InitPlan values to workers via Gather (Merge).
2018-03-29 [3f90ec859] Postpone generate_gather_paths for topmost scan/join rel
2018-03-29 [11cf92f6e] Rewrite the code that applies scan/join targets to paths
-->

       <para>
        Allow single-evaluation queries, e.g. <literal>WHERE</literal>
        clause aggregate queries, and functions in the target list to be
        parallelized (Amit Kapila, Robert Haas)
       </para>
      </listitem>

      <listitem>
<!--
2017-11-15 [e5253fdc4] Add parallel_leader_participation GUC.
-->

       <para>
        Add server parameter <link
        linkend="guc-parallel-leader-participation"><varname>parallel_leader_participation</varname></link>
        to control whether the leader also executes subplans (Thomas Munro)
       </para>

       <para>
        The default is enabled, meaning the leader will execute subplans.
       </para>
      </listitem>

      <listitem>
<!--
2017-10-05 [e9baa5e9f] Allow DML commands that create tables to use parallel qu
-->

       <para>
        Allow parallelization of commands <command>CREATE TABLE
        ... AS</command>, <command>SELECT INTO</command>, and
        <command>CREATE MATERIALIZED VIEW</command> (Haribabu Kommi)
       </para>
      </listitem>

      <listitem>
<!--
2017-08-16 [3cda10f41] Use atomic ops to hand out pages to scan in parallel sca

-->

       <para>
        Improve performance of sequential scans with many parallel workers
        (David Rowley)
       </para>
      </listitem>

      <listitem>
<!--
2017-08-29 [bf11e7ee2] Propagate sort instrumentation from workers back to lead
-->

       <para>
        Add reporting of parallel workers' sort activity in
        <command>EXPLAIN</command> (Robert Haas, Tom Lane)
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Indexes</title>

     <itemizedlist>

      <listitem>
<!--
2018-04-07 [8224de4f4] Indexes with INCLUDE columns and their support in B-tree
-->

       <para>
        Allow B-tree indexes to include columns that are not part of the
        search key or unique constraint, but are available to be read by
        index-only scans (Anastasia Lubennikova, Alexander Korotkov, Teodor
        Sigaev)
       </para>

       <para>
        This is enabled by the new <literal>INCLUDE</literal> clause of <link
        linkend="sql-createindex"><command>CREATE INDEX</command></link>.
        It facilitates building <quote>covering indexes</quote> that optimize
        specific types of queries.  Columns can be included even if their
        data types don't have B-tree support.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-26 [2b2727343] Optimize btree insertions for common case of increasing
2018-04-10 [074251db6] Adjustments to the btree fastpath optimization.
-->

       <para>
        Improve performance of monotonically increasing index additions
        (Pavan Deolasee, Peter Geoghegan)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-22 [7c75ef571] hash: Implement page-at-a-time scan.
-->

       <para>
        Improve performance of hash index scans (Ashutosh Sharma)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-27 [3ad55863e] Add predicate locking for GiST
2018-03-30 [43d1ed60f] Predicate locking in GIN index
2018-04-07 [b508a56f2] Predicate locking in hash indexes.
-->

       <para>
        Add predicate locking for hash, GiST and GIN indexes (Shubham
        Barai)
       </para>

       <para>
        This reduces the likelihood of serialization conflicts in
        serializable-mode transactions.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-27 [c203d6cf8] Allow HOT updates for some expression indexes
-->

       <para>
        Allow heap-only-tuple (<acronym>HOT</acronym>) updates for
        expression indexes when the values of the expressions are unchanged
        (Konstantin Knizhnik)
       </para>

      </listitem>

     </itemizedlist>

     <sect5>
      <title><link linkend="spgist">SP-Gist</link></title>

      <itemizedlist>

      <listitem>
<!--
2018-04-03 [710d90da1] Add prefix operator for TEXT type.
-->

       <para>
        Add prefix-match
        operator <type>text</type> <literal>^@</literal> <type>text</type>,
        which is supported by SP-GiST (Ildus Kurbangaliev)
       </para>

       <para>
        This is similar to using <replaceable>var</replaceable> <literal>LIKE
        'word%'</literal> with a btree index, but it is more efficient.
       </para>
      </listitem>

      <listitem>
<!--
2017-12-25 [ff963b393] Add polygon opclass for SP-GiST
-->

       <para>
        Allow polygons to be indexed with SP-GiST (Nikita Glukhov,
        Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
<!--
2017-12-22 [854823fa3] Add optional compression method to SP-GiST
-->

       <para>
        Allow SP-GiST to use lossy representation of leaf keys (Teodor Sigaev,
        Heikki Linnakangas, Alexander Korotkov, Nikita Glukhov)
       </para>

      </listitem>

      </itemizedlist>

     </sect5>

    </sect4>

    <sect4>
     <title>Optimizer</title>

     <itemizedlist>

      <listitem>
<!--
2018-03-22 [b5db1d93d] Improve ANALYZE's strategy for finding MCVs.
-->

       <para>
        Improve selection of the most common values for statistics
        (Jeff Janes, Dean Rasheed)
       </para>

       <para>
        Previously, the most common values (<acronym>MCV</acronym>s) were
        identified based on their frequency compared to all column
        values.  Now, <acronym>MCV</acronym>s are chosen based on their
        frequency compared to the non-<acronym>MCV</acronym> values.
        This improves the robustness of the algorithm for both uniform and
        non-uniform distributions.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-13 [7d08ce286] Distinguish selectivity of &lt; from &lt;= and &gt; from &gt;=.
-->

       <para>
        Improve selectivity estimates for <literal>&gt;=</literal>
        and <literal>&lt;=</literal> (Tom Lane)
       </para>

       <para>
        Previously, such cases used the same selectivity estimates
        as <literal>&gt;</literal> and <literal>&lt;</literal>, respectively,
        unless the comparison constants are <acronym>MCV</acronym>s.
        This change is particularly helpful for queries
        involving <literal>BETWEEN</literal> with small ranges.
       </para>
      </listitem>

      <listitem>
<!--
2017-10-08 [8ec5429e2] Reduce "X = X" to "X IS NOT NULL", if it's easy to do so
-->

       <para>
        Reduce <replaceable>var</replaceable> <literal>=</literal>
        <replaceable>var</replaceable>
        to <replaceable>var</replaceable> <literal>IS NOT NULL</literal>
        where equivalent (Tom Lane)
       </para>

       <para>
        This leads to better selectivity estimates.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-29 [7ca25b7de] Fix neqjoinsel's behavior for semi/anti join cases.
-->

       <para>
        Improve optimizer's row count estimates for <literal>EXISTS</literal>
        and <literal>NOT EXISTS</literal> queries (Tom Lane)
       </para>
      </listitem>

      <listitem>
<!--
2017-11-02 [7b6c07547] Teach planner to account for HAVING quals in aggregation
-->

       <para>
        Make the optimizer account for evaluation costs and selectivity
        of <literal>HAVING</literal> clauses (Tom Lane)
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
<!--
2018-03-21 [432bb9e04] Basic JIT provider and error handling infrastructure.
2018-03-22 [b96d550eb] Support for optimizing and emitting code in LLVM JIT pro
2018-03-22 [cc415a56d] Basic planner and executor integration for JIT.
2018-03-26 [32af96b2b] JIT tuple deforming in LLVM JIT provider.
2018-03-27 [f4f5845b3] Quick adaption of JIT tuple deforming to the fast defaul
2018-03-28 [9370462e9] Add inlining support to LLVM JIT provider.
2018-09-15 [0fdadfb01] In v11, disable JIT by default (it's still enabled by de
-->

       <para>
        Add <link linkend="jit">Just-in-Time</link>
        (<acronym>JIT</acronym>) compilation of some parts of query plans
        to improve execution speed (Andres Freund)
       </para>

       <para>
        This feature requires <application>LLVM</application> to be
        available.  It is not currently enabled by default, even in
        builds that support it.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-01 [7c70996eb] Allow bitmap scans to operate as index-only scans when p
-->

       <para>
        Allow bitmap scans to perform index-only scans when possible
        (Alexander Kuzmenkov)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-29 [851a26e26] While vacuuming a large table, update upper-level <acronym>FSM</acronym> da
2018-03-30 [c79f6df75] Do index FSM vacuuming sooner.
-->

       <para>
        Update the free space map during <command>VACUUM</command>
        (Claudio Freire)
       </para>

       <para>
        This allows free space to be reused more quickly.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-04 [857f9c36c] Skip full index scan during cleanup of B-tree indexes wh
-->

       <para>
        Allow <command>VACUUM</command> to avoid unnecessary index scans
        (Masahiko Sawada, Alexander Korotkov)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-01 [baaf272ac] Use group updates when setting transaction status in clo
-->

       <para>
        Improve performance of committing multiple concurrent transactions
        (Amit Kapila)
       </para>
      </listitem>

      <listitem>
<!--
2017-10-08 [84ad4b036] Reduce memory usage of targetlist SRFs.
-->

       <para>
        Reduce memory usage for queries using set-returning functions in
        their target lists (Andres Freund)
       </para>
      </listitem>

      <listitem>
<!--
2018-01-09 [69c3936a1] Expression evaluation based aggregate transition invocat
-->

       <para>
        Improve the speed of aggregate computations (Andres Freund)
       </para>
      </listitem>

      <listitem>
<!--
2018-02-07 [1bc0100d2] postgres_fdw: Push down UPDATE/DELETE joins to remote se
-->

       <para>
        Allow <link
        linkend="postgres-fdw"><filename>postgres_fdw</filename></link>
        to push <command>UPDATE</command>s and <command>DELETE</command>s
        using joins to foreign servers (Etsuro Fujita)
       </para>

       <para>
        Previously, only non-join <command>UPDATE</command>s and
        <command>DELETE</command>s were pushed.
       </para>

      </listitem>

      <listitem>
<!--
2018-01-21 [1cc4f536e] Support huge pages on Windows
-->

       <para>
        Add support for <firstterm>large pages</firstterm> on Windows
        (Takayuki Tsunakawa, Thomas Munro)
       </para>

       <para>
        This is controlled by the <link
        linkend="guc-huge-pages">huge_pages</link> configuration
        parameter.
       </para>
      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Monitoring</title>

     <itemizedlist>

      <listitem>
<!--
2017-09-01 [c039ba071] Add memory info to getrusage output
-->

       <para>
        Show memory usage in output from <link
        linkend="runtime-config-statistics-monitor"><varname>log_statement_stats</varname></link>,
        <varname>log_parser_stats</varname>,
        <varname>log_planner_stats</varname>, and
        <varname>log_executor_stats</varname> (Justin Pryzby, Peter
        Eisentraut)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-29 [5373bc2a0] Add background worker type
-->

       <para>
        Add column <link
        linkend="pg-stat-activity-view"><structname>pg_stat_activity</structname>.<structfield>backend_type</structfield></link>
        to show the type of a background worker (Peter Eisentraut)
       </para>

       <para>
        The type is also visible in <application>ps</application> output.
       </para>
      </listitem>

      <listitem>
<!--
2017-12-04 [ab6eaee88] When VACUUM or ANALYZE skips a concurrently dropped tabl
-->

       <para>
        Make <link
        linkend="guc-log-autovacuum-min-duration"><varname>log_autovacuum_min_duration</varname></link>
        log skipped tables that are concurrently being dropped (Nathan
        Bossart)
       </para>

      </listitem>

     </itemizedlist>

     <sect5>
      <title><link linkend="infoschema-tables">Information Schema</link></title>

      <itemizedlist>

      <listitem>
<!--
2018-02-07 [32ff26911] Add more information_schema columns
-->

       <para>
        Add <literal>information_schema</literal> columns related to table
        constraints and triggers (Peter Eisentraut)
       </para>

       <para>
        Specifically,
        <structname>triggers</structname>.<structfield>action_order</structfield>,
        <structname>triggers</structname>.<structfield>action_reference_old_table</structfield>,
        and
        <structname>triggers</structname>.<structfield>action_reference_new_table</structfield>
        are now populated, where before they were always null.  Also,
        <structname>table_constraints</structname>.<structfield>enforced</structfield>
        now exists but is not yet usefully populated.
       </para>

      </listitem>

      </itemizedlist>

     </sect5>
    </sect4>

    <sect4>
     <title><acronym>Authentication</acronym></title>

     <itemizedlist>

      <listitem>
<!--
2017-09-12 [83aaac41c] Allow custom search filters to be configured for LDAP au
-->

       <para>
        Allow the server to specify more complex <link
        linkend="auth-ldap"><acronym>LDAP</acronym></link> specifications
        in search+bind mode (Thomas Munro)
       </para>

       <para>
        Specifically, <literal>ldapsearchfilter</literal> allows pattern matching using
        combinations of <acronym>LDAP</acronym> attributes.
       </para>
      </listitem>

      <listitem>
<!--
2018-01-03 [35c0754fa] Allow ldaps when using ldap authentication
2018-01-04 [3ad2afc2e] Define LDAPS_PORT if it's missing and disable implicit L
-->

       <para>
        Allow <acronym>LDAP</acronym> authentication to use
        encrypted <acronym>LDAP</acronym> (Thomas Munro)
       </para>

       <para>
        We already supported <acronym>LDAP</acronym> over
        <acronym>TLS</acronym> by using <literal>ldaptls=1</literal>.
        This new <acronym>TLS</acronym> <acronym>LDAP</acronym> method for
        encrypted <acronym>LDAP</acronym> is enabled
        with <literal>ldapscheme=ldaps</literal>
        or <literal>ldapurl=ldaps://</literal>.
       </para>
      </listitem>

      <listitem>
<!--
2017-10-12 [cf1238cd9] Log diagnostic messages if errors occur during LDAP auth
-->

       <para>
        Improve logging of <acronym>LDAP</acronym> errors (Thomas Munro)
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Permissions</title>

     <itemizedlist>

      <listitem>
<!--
2018-04-06 [0fdc8495b] Add default roles for file/program access
2018-04-07 [da9b580d8] Refactor dir/file permissions
-->

       <para>
        Add <link linkend="default-roles-table">default roles</link> that
        enable file system access (Stephen Frost)
       </para>

       <para>
        Specifically, the new roles are:
        <literal>pg_read_server_files</literal>,
        <literal>pg_write_server_files</literal>, and
        <literal>pg_execute_server_program</literal>.  These roles now also
        control who can use server-side <command>COPY</command> and the <link
        linkend="file-fdw"><filename>file_fdw</filename></link> extension.
        Previously, only superusers could use these functions, and that
        is still the default behavior.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-06 [e79350fef] Remove explicit superuser checks in favor of ACLs
-->

       <para>
        Allow access to file system functions to be controlled by
        <command>GRANT</command>/<command>REVOKE</command> permissions,
        rather than superuser checks (Stephen Frost)
       </para>

       <para>
        Specifically, these functions were modified: <link
        linkend="functions-admin-genfile-table"><function>pg_ls_dir()</function></link>,
        <function>pg_read_file()</function>,
        <function>pg_read_binary_file()</function>,
        <function>pg_stat_file()</function>.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-09 [5ecc0d738] Restrict lo_import()/lo_export() via SQL permissions not
2017-11-14 [6d776522d] Document changes in large-object privilege checking.
-->

       <para>
        Use <command>GRANT</command>/<command>REVOKE</command>
        to control access to <link
        linkend="lo-import"><function>lo_import()</function></link>
        and <function>lo_export()</function> (Michael Paquier, Tom Lane)
       </para>

       <para>
        Previously, only superusers were granted access to these functions.
       </para>

       <para>
        The compile-time option <literal>ALLOW_DANGEROUS_LO_FUNCTIONS</literal>
        has been removed.
       </para>
      </listitem>

      <listitem>
<!--
2017-12-05 [ab3f008a2] postgres_fdw: Judge password use by run-as user, not ses
-->

       <para>
        Use view owner not session owner when
        preventing non-password access to <link
        linkend="postgres-fdw"><filename>postgres_fdw</filename></link>
        tables (Robert Haas)
       </para>

       <para>
        <productname>PostgreSQL</productname> only allows superusers to
        access <filename>postgres_fdw</filename> tables without
        passwords, e.g. via <literal>peer</literal>.  Previously, the
        session owner had to be a superuser to allow such access; now
        the view owner is checked instead.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-14 [50c6bb022] Fix enforcement of SELECT FOR UPDATE permissions with ne
-->

       <para>
        Fix invalid locking permission check in <command>SELECT FOR
        UPDATE</command> on views (Tom Lane)
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Server Configuration</title>

     <itemizedlist>

      <listitem>
<!--
2018-03-17 [8a3d94252] Add ssl_passphrase_command setting
-->

       <para>
        Add server setting <link
        linkend="guc-ssl-passphrase-command"><varname>ssl_passphrase_command</varname></link>
        to allow supplying of the passphrase for <acronym>SSL</acronym>
        key files (Peter Eisentraut)
       </para>

       <para>
        Also add <link
        linkend="guc-ssl-passphrase-command-supports-reload"><varname>ssl_passphrase_command_supports_reload</varname></link>
        to specify whether the <acronym>SSL</acronym> configuration
        should be reloaded and <varname>ssl_passphrase_command</varname>
        called during a server configuration reload.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-20 [c2513365a] Parameter toast_tuple_target controls TOAST for new rows
-->

       <para>
        Add storage parameter <link
        linkend="sql-createtable-storage-parameters"><varname>toast_tuple_target</varname></link>
        to control the minimum tuple length before <acronym>TOAST</acronym>
        storage will be considered (Simon Riggs)
       </para>

       <para>
        The default <acronym>TOAST</acronym> threshold has not been
        changed.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-12 [6e7baa322] Introduce BYTES unit for GUCs.
2018-05-23 [b06d8e58b] Accept "B" in all memory-unit GUCs, and improve error me
-->

       <para>
        Allow server options related to memory and file sizes to be
        specified in units of bytes (Beena Emerson)
       </para>

       <para>
        The new unit suffix is <quote>B</quote>.  This is in addition to the
        existing units <quote>kB</quote>, <quote>MB</quote>, <quote>GB</quote>
        and <quote>TB</quote>.
       </para>

      </listitem>

    </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="wal">Write-Ahead Log</link> (<acronym>WAL</acronym>)</title>

     <itemizedlist>

      <listitem>
<!--
2017-09-19 [fc49e24fa] Make WAL segment size configurable at initdb time.
-->

       <para>
        Allow the <acronym>WAL</acronym> file size to be set
        during <application>initdb</application> (Beena Emerson)
       </para>

       <para>
        Previously, the 16MB default could only be changed at compile time.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-07 [4b0d28de0] Remove secondary checkpoint
-->

       <para>
        Retain <acronym>WAL</acronym> data for only a single checkpoint
        (Simon Riggs)
       </para>

       <para>
        Previously, <acronym>WAL</acronym> was retained for two checkpoints.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-30 [4a33bb59d] Ensure that WAL pages skipped by a forced WAL switch are
-->

       <para>
        Fill the unused portion of force-switched <acronym>WAL</acronym>
        segment files with zeros for improved compressibility (Chapman
        Flack)
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Base Backup and Streaming Replication</title>

    <itemizedlist>

      <listitem>
<!--
2018-04-07 [5dfd1e5a6] Logical decoding of TRUNCATE
2018-04-07 [039eb6e92] Logical replication support for TRUNCATE
-->

       <para>
        Replicate <command>TRUNCATE</command> activity when using logical
        replication (Simon Riggs, Marco Nenciarini, Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-28 [1eb6d6527] Store 2PC GID in commit/abort WAL recs for logical decod
-->

       <para>
        Pass prepared transaction information to logical replication
        subscribers (Nikhil Sontakke, Stas Kelvich)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-23 [8694cc96b] Exclude unlogged tables from base backups
2018-03-27 [920a5e500] Skip temp tables from basebackup.
2017-11-07 [98267ee83] Exclude pg_internal.init from BASE_BACKUP
-->

       <para>
        Exclude unlogged tables, temporary tables, and
        <filename>pg_internal.init</filename> files from streaming base
        backups (David Steele)
       </para>

       <para>
        There is no need to copy such files.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-03 [4eb77d50c] Validate page level checksums in base backups
-->

       <para>
        Allow checksums of heap pages to be verified during streaming base
        backup (Michael Banck)
       </para>
      </listitem>

      <listitem>
<!--
2018-01-17 [9c7d06d60] Ability to advance replication slots
-->

       <para>
        Allow replication slots to be advanced programmatically, rather
        than be consumed by subscribers (Petr Jelinek)
       </para>

       <para>
        This allows efficient advancement of replication slots when the
        contents do not need to be consumed.  This is performed by
        <function>pg_replication_slot_advance()</function>.
       </para>
      </listitem>

      <listitem>
<!--
2018-01-06 [6271fceb8] Add TIMELINE to backup_label file
-->

       <para>
        Add timeline information to the <link
        linkend="backup-lowlevel-base-backup"><filename>backup_label</filename></link>
        file (Michael Paquier)
       </para>

       <para>
        Also add a check that the <acronym>WAL</acronym> timeline matches
        the <filename>backup_label</filename> file's timeline.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-31 [9a895462d] Enhance pg_stat_wal_receiver view to display host and po
-->

       <para>
        Add host and port connection information to the
        <structname>pg_stat_wal_receiver</structname> system view
        (Haribabu Kommi)
       </para>
      </listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

      <listitem>
<!--
2018-03-28 [16828d5c0] Fast ALTER TABLE ADD COLUMN with a non-NULL default
-->

       <para>
        Allow <command>ALTER TABLE</command> to add a column with
        a non-null default without doing a table rewrite (Andrew Dunstan,
        Serge Rielau)
       </para>

       <para>
        This is enabled when the default value is a constant.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-30 [34c20de4d] Allow to lock views.
2018-03-31 [1b26bd408] Fix bug with view locking code.
-->

       <para>
        Allow views to be locked by locking the underlying tables
        (Yugo Nagata)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-06 [5b6d13eec] Allow SET STATISTICS on expression indexes
-->

       <para>
        Allow <command>ALTER INDEX</command> to set statistics-gathering
        targets for expression indexes (Alexander Korotkov, Adrien Nayrat)
       </para>

       <para>
        In <application>psql</application>, <literal>\d+</literal> now shows
        the statistics target for indexes.
       </para>
      </listitem>

      <listitem>
<!--
2017-10-03 [11d8d72c2] Allow multiple tables to be specified in one VACUUM or A
-->

       <para>
        Allow multiple tables to be specified in one
        <command>VACUUM</command> or <command>ANALYZE</command> command
        (Nathan Bossart)
       </para>

       <para>
        Also, if any table mentioned in <command>VACUUM</command> uses
        a column list, then the <command>ANALYZE</command> keyword must be
        supplied; previously, <command>ANALYZE</command> was implied in
        such cases.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-05 [854dd8cff] Add parenthesized options syntax for ANALYZE.
-->

       <para>
        Add parenthesized options syntax to <command>ANALYZE</command>
        (Nathan Bossart)
       </para>

       <para>
        This is similar to the syntax supported by
        <command>VACUUM</command>.
       </para>
      </listitem>

      <listitem>
<!--
2017-10-14 [4de2d4fba] Explicitly track whether aggregate final functions modif
2017-10-16 [be0ebb65f] Allow the built-in ordered-set aggregates to share trans
-->

       <para>
        Add <command>CREATE AGGREGATE</command> option to specify the
        behavior of the aggregate's finalization function (Tom Lane)
       </para>

       <para>
        This is helpful for allowing user-defined aggregate functions to be
        optimized and to work as window functions.
       </para>

      </listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

      <listitem>
<!--
2017-09-30 [c12d570fa] Support arrays over domains.
-->

       <para>
        Allow the creation of arrays of domains (Tom Lane)
       </para>

       <para>
        This also allows <function>array_agg()</function> to be used
        on domains.
       </para>
      </listitem>

      <listitem>
<!--
2017-10-26 [37a795a60] Support domains over composite types.
2017-10-26 [820c0305f] Support domains over composite types in PL/Tcl.
2017-10-28 [60651e4cd] Support domains over composite types in PL/Perl.
2017-11-16 [687f096ea] Make PL/Python handle domain-type conversions correctly.
-->

       <para>
        Support domains over composite types (Tom Lane)
       </para>

       <para>
        Also allow PL/Perl, PL/Python, and PL/Tcl to handle
        composite-domain function arguments and results.  Also improve
        PL/Python domain handling.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-29 [c0cbe00fe] Add casts from jsonb
-->

       <para>
        Add casts from <type>JSONB</type> scalars to numeric and boolean data
        types (Anastasia Lubennikova)
       </para>

      </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Functions</title>

    <itemizedlist>

      <listitem>
<!--
2018-02-07 [0a459cec9] Support all SQL:2011 options for window frame clauses.
2018-02-24 [8b29e88cd] Add window RANGE support for float4, float8, numeric.
-->

       <para>
        Add all <link linkend="sql-window">window function</link> framing
        options specified by SQL:2011 (Oliver Ford, Tom Lane)
       </para>

       <para>
        Specifically, allow <literal>RANGE</literal> mode to use
        <literal>PRECEDING</literal> and <literal>FOLLOWING</literal> to
        select rows having grouping values within plus or minus the
        specified offset.  Add <literal>GROUPS</literal> mode to include plus
        or minus the number of peer groups.  Frame exclusion syntax was also
        added.
       </para>

      </listitem>

      <listitem>
<!--
2018-02-22 [10cfce34c] Add user-callable SHA-2 functions
-->

       <para>
        Add <acronym>SHA-2</acronym> family of hash functions (Peter
        Eisentraut)
       </para>

       <para>
        Specifically, <link
        linkend="functions-binarystring-other"><function>sha224()</function></link>,
        <function>sha256()</function>, <function>sha384()</function>,
        <function>sha512()</function> were added.
       </para>
      </listitem>

      <listitem>
<!--
2017-08-31 [81c5e46c4] Introduce 64-bit hash functions with a 64-bit seed.
-->

       <para>
        Add support for 64-bit non-cryptographic hash functions (Robert
        Haas, Amul Sul)
       </para>
      </listitem>

      <listitem>
<!--
2018-01-09 [11b623dd0] Implement TZH and TZM timestamp format patterns
-->

       <para>
        Allow <function>to_char()</function> and
        <function>to_timestamp()</function> to specify the time zone's
        offset from <acronym>UTC</acronym> in hours and minutes
        (Nikita Glukhov, Andrew Dunstan)
       </para>

       <para>
        This is done with format specifications <link
        linkend="functions-formatting-datetime-table"><literal>TZH</literal></link>
        and <literal>TZM</literal>.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-05 [1664ae197] Add websearch_to_tsquery
-->

       <para>
        Add text search function <link
        linkend="textsearch-functions-table"><function>websearch_to_tsquery()</function></link>
        that supports a query syntax similar to that used by web search
        engines (Victor Drobny, Dmitry Ivanov)
       </para>
      </listitem>

      <listitem>
<!--
2018-04-07 [1c1791e00] Add json(b)_to_tsvector function
-->

       <para>
        Add functions <link
        linkend="textsearch-functions-table"><function>json(b)_to_tsvector()</function></link>
        to create a text search query for matching
        <type>JSON</type>/<type>JSONB</type> values (Dmitry Dolgov)
       </para>

      </listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

      <listitem>
<!--
2017-11-30 [e4128ee76] SQL procedures
2018-02-22 [76b6aa41f] Support parameters in CALL
2018-03-14 [33803f67f] Support INOUT arguments in procedures
2018-04-14 [a8677e3ff] Support named and default arguments in CALL
2018-08-22 [e0dc839e7] Change PROCEDURE to FUNCTION in CREATE TRIGGER syntax
2018-08-22 [fd4417e8a] Change PROCEDURE to FUNCTION in CREATE OPERATOR syntax
-->

       <para>
        Add SQL-level procedures, which can start and commit their own
        transactions (Peter Eisentraut)
       </para>

       <para>
        They are created with the new <link
        linkend="sql-createprocedure"><command>CREATE
        PROCEDURE</command></link> command and invoked via <link
        linkend="sql-call"><command>CALL</command></link>.
       </para>

       <para>
        The new <command>ALTER</command>/<command>DROP ROUTINE</command>
        commands allow altering/dropping of all routine-like objects,
        including procedures, functions, and aggregates.
       </para>

       <para>
        Also, writing <literal>FUNCTION</literal> is now preferred
        over writing <literal>PROCEDURE</literal> in <command>CREATE
        OPERATOR</command> and <command>CREATE TRIGGER</command>, because the
        referenced object must be a function not a procedure.  However, the
        old syntax is still accepted for compatibility.
       </para>
      </listitem>

      <listitem>
<!--
2018-01-22 [8561e4840] Transaction control in PL procedures
2018-03-28 [d92bc83c4] PL/pgSQL: Nested CALL with transactions
2018-03-28 [056a5a3f6] Allow committing inside cursor loop
2018-04-05 [b981275b6] PL/pgSQL: Add support for SET TRANSACTION
-->

       <para>
        Add transaction control to PL/pgSQL, PL/Perl, PL/Python, PL/Tcl,
        and <acronym>SPI</acronym> server-side languages (Peter Eisentraut)
       </para>

       <para>
        Transaction control is only available within top-transaction-level
        procedures and nested <command>DO</command> and
        <command>CALL</command> blocks that only contain other
        <command>DO</command> and <command>CALL</command> blocks.
       </para>
      </listitem>

      <listitem>
<!--
2018-02-13 [f9263006d] Support CONSTANT/NOT NULL/initial value for plpgsql comp
-->

       <para>
        Add the ability to define PL/pgSQL composite-type variables as not
        null, constant, or with initial values (Tom Lane)
       </para>
      </listitem>

      <listitem>
<!--
2018-02-13 [4b93f5799] Make plpgsql use its DTYPE_REC code paths for composite-

-->

       <para>
        Allow PL/pgSQL to handle changes to composite types (e.g. record,
        row) that happen between the first and later function executions
        in the same session (Tom Lane)
       </para>

       <para>
        Previously, such circumstances generated errors.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-28 [3f44e3db7] Transforms for jsonb to PL/Python
-->

       <para>
        Add extension <filename>jsonb_plpython</filename> to
        transform <type>JSONB</type> to/from PL/Python types (Anthony
        Bykov)
       </para>
      </listitem>

      <listitem>
<!--
2018-04-03 [341e16618] Transforms for jsonb to PL/Perl
-->

       <para>
        Add extension <filename>jsonb_plperl</filename> to transform
        <type>JSONB</type> to/from PL/Perl types (Anthony Bykov)
       </para>

      </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Client Interfaces</title>

    <itemizedlist>

      <listitem>
<!--
2018-03-17 [e3bdb2d92] Set libpq sslcompression to off by default
-->

       <para>
        Change libpq to disable compression by default (Peter Eisentraut)
       </para>

       <para>
        Compression is already disabled in modern OpenSSL versions, so that
        the libpq setting had no effect with such libraries.
       </para>
      </listitem>

      <listitem>
<!--
2017-08-25 [d22e9d530] Implement <literal>DO CONTINUE</literal> action for <literal>ECPG WHENEVER</literal> statement
-->

       <para>
        Add <literal>DO CONTINUE</literal> option
        to <application>ecpg</application>'s <literal>WHENEVER</literal>
        statement (Vinayak Pokale)
       </para>

       <para>
        This generates a C <command>continue</command> statement, causing a
        return to the top of the contained loop when the specified condition
        occurs.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-14 [3b7ab4380] Add Oracle like handling of char arrays.
-->

       <para>
        Add an <application>ecpg</application> mode to enable Oracle
        Pro*C-style handling of char arrays.
       </para>

       <para>
        This mode is enabled with <option>-C</option>.
       </para>

      </listitem>

    </itemizedlist>

   </sect3>

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

    <sect4>
     <title><xref linkend="app-psql"/></title>

     <itemizedlist>

      <listitem>
<!--
2017-09-05 [49ca462eb] Add \gdesc psql command.
-->

       <para>
        Add <application>psql</application> command <literal>\gdesc</literal>
        to display the names and types of the columns in a query result
        (Pavel Stehule)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-12 [69835bc89] Add psql variables to track success/failure of SQL queri
-->

       <para>
        Add <application>psql</application> variables to report query
        activity and errors (Fabien Coelho)
       </para>

       <para>
        Specifically, the new variables are <literal>ERROR</literal>,
        <literal>SQLSTATE</literal>, <literal>ROW_COUNT</literal>,
        <literal>LAST_ERROR_MESSAGE</literal>, and
        <literal>LAST_ERROR_SQLSTATE</literal>.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-21 [d57c7a7c5] Provide a test for variable existence in psql
-->

       <para>
        Allow <application>psql</application> to test for the existence
        of a variable (Fabien Coelho)
       </para>

       <para>
        Specifically, the syntax <literal>:{?variable_name}</literal> allows
        a variable's existence to be tested in an <literal>\if</literal>
        statement.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-05 [5e8304fdc] In psql, use PSQL_PAGER in preference to PAGER, if it's
-->

       <para>
        Allow environment variable <envar>PSQL_PAGER</envar> to control
        <application>psql</application>'s pager (Pavel Stehule)
       </para>

       <para>
        This allows <application>psql</application>'s default pager to
        be specified as a separate environment variable from the pager
        for other applications.  <envar>PAGER</envar> is still honored
        if <envar>PSQL_PAGER</envar> is not set.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-23 [05b6ec39d] Show partition info from psql \d+
-->

       <para>
        Make psql's <literal>\d+</literal> command always show the table's
        partitioning information (Amit Langote, Ashutosh Bapat)
       </para>

       <para>
        Previously, partition information would not be displayed for a
        partitioned table if it had no partitions.  Also indicate which
        partitions are themselves partitioned.
       </para>
      </listitem>

      <listitem>
<!--
2018-01-29 [15be27460] Avoid misleading psql password prompt when username is m
-->

       <para>
        Ensure that <application>psql</application> reports the proper user
        name when prompting for a password (Tom Lane)
       </para>

       <para>
        Previously, combinations of <option>-U</option> and a user name
        embedded in a <acronym>URI</acronym> caused incorrect reporting.
        Also suppress the user name before the password prompt when
        <option>--password</option> is specified.
       </para>
      </listitem>

      <listitem>
<!--
2018-02-01 [df9f599bc] psql:  Add quit/help behavior/hint, for other tool porta
-->

       <para>
        Allow <command>quit</command> and <command>exit</command> to
        exit <application>psql</application> when given with no prior input
        (Bruce Momjian)
       </para>

       <para>
        Also print hints about how to exit when <command>quit</command> and
        <command>exit</command> are used alone on a line while the input
        buffer is not empty.  Add a similar hint for <command>help</command>.
       </para>
      </listitem>

      <listitem>
<!--
2018-02-12 [91389228a] psql:  give ^D hint for \q in place where \q is ignored
-->

       <para>
        Make <application>psql</application> hint at using control-D
        when <command>\q</command> is entered alone on a line but ignored
        (Bruce Momjian)
       </para>

       <para>
        For example, <command>\q</command> does not exit when supplied
        in character strings.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-03 [2b8c94e1b] Improve tab-completion for ALTER INDEX RESET/SET.
-->

       <para>
        Improve tab completion for <command>ALTER INDEX
        RESET</command>/<command>SET</command> (Masahiko Sawada)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-05 [722408bcd] Add infrastructure to support server-version-dependent t
-->

       <para>
        Add infrastructure to allow <application>psql</application>
        to adapt its tab completion queries based on the server version
        (Tom Lane)
       </para>

       <para>
        Previously, tab completion queries could fail against older servers.
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

      <listitem>
<!--
2018-01-09 [bc7fa0c15] Improve scripting language in pgbench
-->

       <para>
        Add <application>pgbench</application> expression support for
        NULLs, booleans, and some functions and operators (Fabien Coelho)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-22 [f67b113ac] Add \if support to pgbench
-->

       <para>
        Add <literal>\if</literal> conditional support to
        <application>pgbench</application> (Fabien Coelho)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-04 [9d36a3866] Adjust pgbench to allow non-ASCII characters in variable
-->

       <para>
        Allow the use of non-<acronym>ASCII</acronym> characters in
        <application>pgbench</application> variable names (Fabien Coelho)
       </para>
      </listitem>

      <listitem>
<!--
2017-11-13 [591c504fa] Allow running just selected steps of pgbench's initializ
-->

       <para>
        Add <application>pgbench</application> option
        <option>--init-steps</option> to control the initialization steps
        performed (Masahiko Sawada)
       </para>
      </listitem>

      <listitem>
<!--
2017-12-14 [1fcd0adeb] Add approximated Zipfian-distributed random generator to
-->

       <para>
        Add an approximately Zipfian-distributed random generator to
        <application>pgbench</application> (Alik Khilazhev)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-26 [64f85894a] Set random seed for pgbench.
-->

       <para>
        Allow the random seed to be set in
        <application>pgbench</application> (Fabien Coelho)
       </para>
      </listitem>

      <listitem>
<!--
2017-12-27 [7a727c180] Add pow(), aka power(), function to pgbench.
-->

       <para>
        Allow <application>pgbench</application> to do exponentiation
        with <function>pow()</function> and <function>power()</function>
        (Ra&uacute;l Mar&iacute;n Rodr&iacute;guez)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-21 [e51a04840] Add general purpose hasing functions to pgbench.
-->

       <para>
        Add hashing functions to <application>pgbench</application>
        (Ildar Musin)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-04 [c23bb6bad] Fix some subtle problems in pgbench transaction stats co
2017-11-21 [16827d442] pgbench: fix stats reporting when some transactions are
-->

       <para>
        Make <application>pgbench</application> statistics more
        accurate when using <option>--latency-limit</option> and
        <option>--rate</option> (Fabien Coelho)
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3>
    <title>Server Applications</title>

    <itemizedlist>

      <listitem>
<!--
2017-09-27 [3709ca1cf] pg_basebackup: Add option to create replication slot
-->

       <para>
        Add an option to <link
        linkend="app-pgbasebackup"><application>pg_basebackup</application></link>
        that creates a named replication slot (Michael Banck)
       </para>

       <para>
        The option <option>--create-slot</option> creates
        the named replication slot (<option>--slot</option>)
        when the <acronym>WAL</acronym> streaming method
        (<option>--wal-method=stream</option>) is used.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-07 [c37b3d08c] Allow group access on PGDATA
-->

       <para>
        Allow <link
        linkend="app-initdb"><application>initdb</application></link>
        to set group read access to the data directory (David Steele)
       </para>

       <para>
        This is accomplished with the new initdb option
        <option>--allow-group-access</option>.  Administrators
        can also set group permissions on the empty data
        directory before running initdb.  Server variable <link
        linkend="guc-data-directory"><varname>data_directory_mode</varname></link>
        allows reading of data directory group permissions.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-05 [1fde38bea] Allow on-line enabling and disabling of data checksums
2018-04-09 [a228cc13a] Revert "Allow on-line enabling and disabling of data che
-->

       <para>
        Add <link
        linkend="pgverifychecksums"><application>pg_verify_checksums</application></link>
        tool to verify database checksums while offline (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-25 [bf4a8676c] pg_resetwal: Allow users to change the WAL segment size
-->

       <para>
        Allow <link
        linkend="app-pgresetwal"><application>pg_resetwal</application></link>
        to change the <acronym>WAL</acronym> segment size via
        <option>--wal-segsize</option> (Nathan Bossart)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-24 [e22b27f0c] Add long options to pg_resetwal and pg_controldata
-->

       <para>
        Add long options to <application>pg_resetwal</application>
        and <application>pg_controldata</application> (Nathan Bossart,
        Peter Eisentraut)
       </para>
      </listitem>

      <listitem>
<!--
2017-10-29 [5f3971291] pg_receivewal: Add - -no-sync option.
-->

       <para>
        Add <link
        linkend="app-pgreceivewal"><application>pg_receivewal</application></link>
        option <option>--no-sync</option> to prevent synchronous
        <acronym>WAL</acronym> writes, for testing (Michael Paquier)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-11 [6d9fa5264] pg_receivewal: Add - -endpos option
-->

       <para>
        Add <application>pg_receivewal</application> option
        <option>--endpos</option> to specify when <acronym>WAL</acronym>
        receiving should stop (Michael Paquier)
       </para>
      </listitem>

      <listitem>
<!--
2017-10-01 [2e83db3ad] Allow pg_ctl kill to send SIGKILL.
-->

       <para>
        Allow <link
        linkend="app-pg-ctl"><application>pg_ctl</application></link>
        to send the <literal>SIGKILL</literal> signal to processes
        (Andres Freund)
       </para>

       <para>
        This was previously unsupported due to concerns over possible misuse.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-29 [266b6acb3] Make pg_rewind skip files and directories that are remov
-->

       <para>
        Reduce the number of files copied by <link
        linkend="app-pgrewind"><application>pg_rewind</application></link>
        (Michael Paquier)
       </para>
      </listitem>

      <listitem>
<!--
2018-04-09 [5d5aeddab] Make sure pg_rewind can't run as root
-->

       <para>
        Prevent <application>pg_rewind</application> from running as
        <literal>root</literal> (Michael Paquier)
       </para>

      </listitem>

     </itemizedlist>

    <sect4>
     <title><link linkend="app-pgdump"><application>pg_dump</application></link>,
     <link linkend="app-pg-dumpall"><application>pg_dumpall</application></link>,
     <link linkend="app-pgrestore"><application>pg_restore</application></link></title>

     <itemizedlist>

      <listitem>
<!--
2017-09-01 [84be67181] pg_dumpall: Add a -E flag to set the encoding, like pg_d
-->

       <para>
        Add <application>pg_dumpall</application> option
        <option>--encoding</option> to control output encoding
        (Michael Paquier)
       </para>

       <para>
        <application>pg_dump</application> already had this option.
       </para>
      </listitem>

      <listitem>
<!--
2017-08-14 [23d7680d0] pg_dump: Add a - -load-via-partition-root option.
-->

       <para>
        Add <application>pg_dump</application> option
        <option>--load-via-partition-root</option> to force loading of
        data into the partition's root table, rather than the original
        partition (Rushabh Lathia)
       </para>

       <para>
        This is useful if the system to be loaded to has different collation
        definitions or endianness, possibly requiring rows to be stored in
        different partitions than previously.
       </para>
      </listitem>

      <listitem>
<!--
2018-01-25 [1368e92e1] Support - -no-comments in pg_dump, pg_dumpall, pg_restore
-->

       <para>
        Add an option to suppress dumping and restoring database object
        comments (Robins Tharakan)
       </para>

       <para>
        The new <application>pg_dump</application>,
        <application>pg_dumpall</application>, and
        <application>pg_restore</application> option is
        <option>--no-comments</option>.
       </para>

      </listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

      <listitem>
<!--
2018-07-31 [d06eebce5] Provide for contrib and pgxs modules to install include
2018-09-05 [235526a20] Allow extensions to install built as well as unbuilt hea
2018-09-07 [094ffd684] Refactor installation of extension headers.
2018-09-16 [f1ca5a654] Fix out-of-tree build for transform modules.
-->
       <para>
        Add <application>PGXS</application> support for installing include
        files (Andrew Gierth)
       </para>

       <para>
        This supports creating extension modules that depend on other
        modules.  Formerly there was no easy way for the dependent module to
        find the referenced one's include files.  Several
        existing <filename>contrib</filename> modules that define data types
        have been adjusted to install relevant files.  Also, PL/Perl and
        PL/Python now install their include files, to support creation of
        transform modules for those languages.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-05 [1fd869066] Install errcodes.txt for use by extensions.
-->

       <para>
        Install <filename>errcodes.txt</filename> to allow extensions to access
        the list of error codes known to <productname>PostgreSQL</productname>
        (Thomas Munro)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-06 [1c53f612b] Escape &lt; and &amp; in SGML
2017-10-17 [c29c57890] Don't use SGML empty tags
2017-10-20 [1ff01b390] Convert SGML IDs to lower case
2017-11-23 [3c49c6fac] Convert documentation to DocBook XML
-->

       <para>
        Convert documentation to DocBook <acronym>XML</acronym> (Peter
        Eisentraut, Alexander Lakhin, J&uuml;rgen Purtz)
       </para>

       <para>
        The file names still use an <filename>sgml</filename> extension
        for compatibility with back branches.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-22 [9a95a77d9] Use stdbool.h if suitable
2018-03-23 [7ba7986fb] Fix interaction of Perl and stdbool.h
2018-05-02 [6fe25c135] Change SIZEOF_BOOL to 1 for Windows.
-->

       <para>
        Use <filename>stdbool.h</filename> to define type <type>bool</type>
        on platforms where it's suitable, which is most (Peter Eisentraut)
       </para>

       <para>
        This eliminates a coding hazard for extension modules that need
        to include <filename>stdbool.h</filename>.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-03 [a351679c8] Trivial adjustments in preparation for bootstrap data co
2018-04-08 [372728b0d] Replace our traditional initial-catalog-data format with
2018-04-17 [e90d4ddc6] Simplify genbki.pl's data quoting rules.
2018-04-17 [9ffcccdb9] Rationalize handling of array type names in bootstrap da
2018-04-17 [55d26ff63] Rationalize handling of single and double quotes in boot
2018-04-18 [5372c2c84] Improve error detection/reporting in Catalog.pm and genb
2018-04-26 [a0854f107] Avoid parsing catalog data twice during BKI file constru
2018-05-05 [d160882a1] Fix bootstrap parser so that its keywords are unreserved
-->

       <para>
        Overhaul the way that initial system catalog contents are defined
        (John Naylor)
       </para>

       <para>
        The initial data is now represented in Perl data structures, making
        it much easier to manipulate mechanically.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-21 [846b5a525] Prevent extensions from creating custom GUCs that are GU
-->

       <para>
        Prevent extensions from creating custom server parameters that
        take a quoted list of values (Tom Lane)
       </para>

       <para>
        This cannot be supported at present because knowledge of the
        parameter's property would be required even before the extension is
        loaded.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-18 [9288d62bb] Support channel binding 'tls-unique' in SCRAM
2017-12-19 [4bbf110d2] Add libpq connection parameter "scram_channel_binding"
2018-01-04 [d3fb72ea6] Implement channel binding tls-server-end-point for SCRAM
-->

       <para>
        Add ability to use channel binding when using <link
        linkend="auth-password"><acronym>SCRAM</acronym></link>
        authentication (Michael Paquier)
       </para>

       <para>
        Channel binding is intended to prevent man-in-the-middle attacks, but
        <acronym>SCRAM</acronym> cannot prevent them unless it can be forced
        to be active.  Unfortunately, there is no way to do that in libpq.
        Support for it is expected in future versions of libpq and in
        interfaces not built using libpq, e.g. JDBC.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-05 [eed1ce72e] Allow background workers to bypass datallowconn
-->

       <para>
        Allow background workers to attach to databases that normally
        disallow connections (Magnus Hagander)
       </para>
      </listitem>

      <listitem>
<!--
2018-04-04 [f044d71e3] Use ARMv8 CRC instructions where available.
-->

       <para>
        Add support for hardware <acronym>CRC</acronym> calculations
        on <productname>ARMv8</productname> (Yuqi Gu, Heikki Linnakangas,
        Thomas Munro)
       </para>
      </listitem>

      <listitem>
<!--
2017-10-04 [212e6f34d] Replace binary search in fmgr_isbuiltin with a lookup ar
-->

       <para>
        Speed up lookups of built-in functions by OID (Andres Freund)
       </para>

       <para>
        The previous binary search has been replaced by a lookup array.
       </para>
      </listitem>

      <listitem>
<!--
2017-10-11 [1de09ad8e] Add more efficient functions to pqformat API.
-->

       <para>
        Speed up construction of query results (Andres Freund)
       </para>
      </listitem>

      <listitem>
<!--
2017-10-13 [141fd1b66] Improve sys/catcache performance.
-->

       <para>
        Improve speed of access to system caches (Andres Freund)
       </para>
      </listitem>

      <listitem>
<!--
2017-11-23 [a4ccc1cef] Generational memory allocator
-->

       <para>
        Add a generational memory allocator which is optimized for serial
        allocation/deallocation (Tomas Vondra)
       </para>

       <para>
        This reduces memory usage for logical decoding.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-22 [7c91a0364] Sync up our various ways of estimating pg_class.reltuple
-->

       <para>
        Make the computation of
        <structname>pg_class</structname>.<structfield>reltuples</structfield>
        by <command>VACUUM</command> consistent with its computation
        by <command>ANALYZE</command> (Tomas Vondra)
       </para>
      </listitem>

      <listitem>
<!--
2018-04-25 [46cda5bf7] Change pgindent/README to specify that we use perltidy v
2018-04-27 [a2ada08d4] perltidy: Don't write backup files
-->

       <para>
        Update to use <application>perltidy</application> version
        <literal>20170521</literal> (Tom Lane, Peter Eisentraut)
       </para>
      </listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

      <listitem>
<!--
2017-08-21 [79ccd7cbd] pg_prewarm: Add automatic prewarm feature.
-->

       <para>
        Allow extension <link
        linkend="pgprewarm"><filename>pg_prewarm</filename></link>
        to restore the previous shared buffer contents on startup (Mithun
        Cy, Robert Haas)
       </para>

       <para>
        This is accomplished by having <filename>pg_prewarm</filename> store
        the shared buffers' relation and block number data to disk
        occasionally during server operation, and at shutdown.
       </para>
      </listitem>

      <listitem>
<!--
2018-03-21 [be8a7a686] Add strict_word_similarity to pg_trgm module
-->

       <para>
        Add <link linkend="pgtrgm"><filename>pg_trgm</filename></link>
        function <function>strict_word_similarity()</function> to compute
        the similarity of whole words (Alexander Korotkov)
       </para>

       <para>
        The function <function>word_similarity()</function> already
        existed for this purpose, but it was designed to find similar
        parts of words, while <function>strict_word_similarity()</function>
        computes the similarity to whole words.
       </para>
      </listitem>

      <listitem>
<!--
2017-09-19 [f24649976] Add citext_pattern_ops for citext contrib module
-->

       <para>
        Allow creation of indexes that can be used by <literal>LIKE</literal>
        comparisons
        on <link linkend="citext"><filename>citext</filename></link> columns
        (Alexey Chernyshov)
       </para>

       <para>
        To do this, the index must be created using the
        <literal>citext_pattern_ops</literal> operator class.
       </para>
      </listitem>

      <listitem>
<!--
2018-04-05 [f4cd7102b] Add support of bool, bpchar, name and uuid to btree_gin
-->

       <para>
        Allow <link
        linkend="btree-gin"><filename>btree_gin</filename></link>
        to index <type>bool</type>, <type>bpchar</type>, <type>name</type>
        and <type>uuid</type> data types (Matheus Oliveira)
       </para>
      </listitem>

      <listitem>
<!--
2017-11-20 [de1d042f5] Support index-only scans in contrib/cube and contrib/seg
-->

       <para>
        Allow <link linkend="cube"><filename>cube</filename></link>
        and <link linkend="seg"><filename>seg</filename></link>
        extensions to perform index-only scans using GiST indexes
        (Andrey Borodin)
       </para>
      </listitem>

      <listitem>
<!--
2018-01-11 [f50c80dbb] llow negative coordinate for ~&gt; (cube, int) operator
-->

       <para>
        Allow retrieval of negative cube coordinates using
        the <literal>~&gt;</literal> operator (Alexander Korotkov)
       </para>

       <para>
        This is useful for KNN-GiST searches when looking for coordinates in
        descending order.
       </para>
      </listitem>

      <listitem>
<!--
2017-08-16 [ec0a69e49] Extend the default rules file for contrib/unaccent with
-->

       <para>
        Add Vietnamese letter handling to the <link
        linkend="unaccent"><filename>unaccent</filename></link>
        extension (Dang Minh Huong, Michael Paquier)
       </para>
      </listitem>

      <listitem>
<!--
2018-03-31 [7f563c09f] Add amcheck verification of heap relations belonging to
-->

       <para>
        Enhance <link
        linkend="amcheck"><filename>amcheck</filename></link>
        to check that each heap tuple has an index entry (Peter Geoghegan)
       </para>
      </listitem>

      <listitem>
<!--
2018-04-06 [11523e860] Support new default roles with adminpack
-->

       <para>
        Have <link
        linkend="adminpack"><filename>adminpack</filename></link>
        use the new default file system access roles (Stephen Frost)
       </para>

       <para>
        Previously, only superusers could call <filename>adminpack</filename>
        functions; now role permissions are checked.
       </para>
      </listitem>

      <listitem>
<!--
2017-10-11 [cff440d36] pg_stat_statements: Widen query IDs from 32 bits to 64 b
-->

       <para>
        Widen <structname>pg_stat_statement</structname>'s query ID
        to 64 bits (Robert Haas)
       </para>

       <para>
        This greatly reduces the chance of query ID hash collisions.
        The query ID can now potentially display as a negative value.
       </para>
      </listitem>

      <listitem>
<!--
2017-11-17 [527878635] Remove contrib/start-scripts/osx/.
-->

       <para>
        Remove the <filename>contrib/start-scripts/osx</filename> scripts
        since they are no longer recommended
        (use <filename>contrib/start-scripts/macos</filename> instead)
        (Tom Lane)
       </para>
      </listitem>

      <listitem>
<!--
2017-09-22 [5d3cad564] Remove contrib/chkpass
-->

       <para>
        Remove the <filename>chkpass</filename> extension (Peter Eisentraut)
       </para>

       <para>
        This extension is no longer considered to be a usable security tool
        or example of how to write an extension.
       </para>

      </listitem>

    </itemizedlist>

   </sect3>

  </sect2>

  <sect2>
   <title>Acknowledgments</title>

   <para>
    The following individuals (in alphabetical order) have contributed to this
    release as patch authors, committers, reviewers, testers, or reporters of
    issues.
   </para>

   <simplelist>
    <member>Abhijit Menon-Sen</member>
    <member>Adam Bielanski</member>
    <member>Adam Brightwell</member>
    <member>Adam Brusselback</member>
    <member>Aditya Toshniwal</member>
    <member>Adrián Escoms</member>
    <member>Adrien Nayrat</member>
    <member>Akos Vandra</member>
    <member>Aleksander Alekseev</member>
    <member>Aleksandr Parfenov</member>
    <member>Alexander Korotkov</member>
    <member>Alexander Kukushkin</member>
    <member>Alexander Kuzmenkov</member>
    <member>Alexander Lakhin</member>
    <member>Alexandre Garcia</member>
    <member>Alexey Bashtanov</member>
    <member>Alexey Chernyshov</member>
    <member>Alexey Kryuchkov</member>
    <member>Alik Khilazhev</member>
    <member>Álvaro Herrera</member>
    <member>Amit Kapila</member>
    <member>Amit Khandekar</member>
    <member>Amit Langote</member>
    <member>Amul Sul</member>
    <member>Anastasia Lubennikova</member>
    <member>Andreas Joseph Krogh</member>
    <member>Andreas Karlsson</member>
    <member>Andreas Seltenreich</member>
    <member>André Hänsel</member>
    <member>Andrei Gorita</member>
    <member>Andres Freund</member>
    <member>Andrew Dunstan</member>
    <member>Andrew Fletcher</member>
    <member>Andrew Gierth</member>
    <member>Andrew Grossman</member>
    <member>Andrew Krasichkov</member>
    <member>Andrey Borodin</member>
    <member>Andrey Lizenko</member>
    <member>Andy Abelisto</member>
    <member>Anthony Bykov</member>
    <member>Antoine Scemama</member>
    <member>Anton Dignös</member>
    <member>Antonin Houska</member>
    <member>Arseniy Sharoglazov</member>
    <member>Arseny Sher</member>
    <member>Arthur Zakirov</member>
    <member>Ashutosh Bapat</member>
    <member>Ashutosh Sharma</member>
    <member>Ashwin Agrawal</member>
    <member>Asim Praveen</member>
    <member>Atsushi Torikoshi</member>
    <member>Badrul Chowdhury</member>
    <member>Balazs Szilfai</member>
    <member>Basil Bourque</member>
    <member>Beena Emerson</member>
    <member>Ben Chobot</member>
    <member>Benjamin Coutu</member>
    <member>Bernd Helmle</member>
    <member>Blaz Merela</member>
    <member>Brad DeJong</member>
    <member>Brent Dearth</member>
    <member>Brian Cloutier</member>
    <member>Bruce Momjian</member>
    <member>Catalin Iacob</member>
    <member>Chad Trabant</member>
    <member>Chapman Flack</member>
    <member>Christian Duta</member>
    <member>Christian Ullrich</member>
    <member>Christoph Berg</member>
    <member>Christoph Dreis</member>
    <member>Christophe Courtois</member>
    <member>Christopher Jones</member>
    <member>Claudio Freire</member>
    <member>Clayton Salem</member>
    <member>Craig Ringer</member>
    <member>Dagfinn Ilmari Mannsåker</member>
    <member>Dan Vianello</member>
    <member>Dan Watson</member>
    <member>Dang Minh Huong</member>
    <member>Daniel Gustafsson</member>
    <member>Daniel Vérité</member>
    <member>Daniel Westermann</member>
    <member>Daniel Wood</member>
    <member>Darafei Praliaskouski</member>
    <member>Dave Cramer</member>
    <member>Dave Page</member>
    <member>David Binderman</member>
    <member>David Carlier</member>
    <member>David Fetter</member>
    <member>David G. Johnston</member>
    <member>David Gould</member>
    <member>David Hinkle</member>
    <member>David Pereiro Lagares</member>
    <member>David Rader</member>
    <member>David Rowley</member>
    <member>David Steele</member>
    <member>Davy Machado</member>
    <member>Dean Rasheed</member>
    <member>Dian Fay</member>
    <member>Dilip Kumar</member>
    <member>Dmitriy Sarafannikov</member>
    <member>Dmitry Dolgov</member>
    <member>Dmitry Ivanov</member>
    <member>Dmitry Shalashov</member>
    <member>Don Seiler</member>
    <member>Doug Doole</member>
    <member>Doug Rady</member>
    <member>Edmund Horner</member>
    <member>Eiji Seki</member>
    <member>Elvis Pranskevichus</member>
    <member>Emre Hasegeli</member>
    <member>Erik Rijkers</member>
    <member>Erwin Brandstetter</member>
    <member>Etsuro Fujita</member>
    <member>Euler Taveira</member>
    <member>Everaldo Canuto</member>
    <member>Fabien Coelho</member>
    <member>Fabrízio de Royes Mello</member>
    <member>Feike Steenbergen</member>
    <member>Frits Jalvingh</member>
    <member>Fujii Masao</member>
    <member>Gao Zengqi</member>
    <member>Gianni Ciolli</member>
    <member>Greg Stark</member>
    <member>Gunnlaugur Thor Briem</member>
    <member>Guo Xiang Tan</member>
    <member>Hadi Moshayedi</member>
    <member>Hailong Li</member>
    <member>Haribabu Kommi</member>
    <member>Heath Lord</member>
    <member>Heikki Linnakangas</member>
    <member>Hugo Mercier</member>
    <member>Igor Korot</member>
    <member>Igor Neyman</member>
    <member>Ildar Musin</member>
    <member>Ildus Kurbangaliev</member>
    <member>Ioseph Kim</member>
    <member>Jacob Champion</member>
    <member>Jaime Casanova</member>
    <member>Jakob Egger</member>
    <member>Jean-Pierre Pelletier</member>
    <member>Jeevan Chalke</member>
    <member>Jeevan Ladhe</member>
    <member>Jeff Davis</member>
    <member>Jeff Janes</member>
    <member>Jeremy Evans</member>
    <member>Jeremy Finzel</member>
    <member>Jeremy Schneider</member>
    <member>Jesper Pedersen</member>
    <member>Jim Nasby</member>
    <member>Jimmy Yih</member>
    <member>Jing Wang</member>
    <member>Jobin Augustine</member>
    <member>Joe Conway</member>
    <member>John Gorman</member>
    <member>John Naylor</member>
    <member>Jon Nelson</member>
    <member>Jon Wolski</member>
    <member>Jonathan Allen</member>
    <member>Jonathan S. Katz</member>
    <member>Julien Rouhaud</member>
    <member>Jürgen Purtz</member>
    <member>Justin Pryzby</member>
    <member>KaiGai Kohei</member>
    <member>Kaiting Chen</member>
    <member>Karl Lehenbauer</member>
    <member>Keith Fiske</member>
    <member>Kevin Bloch</member>
    <member>Kha Nguyen</member>
    <member>Kim Rose Carlsen</member>
    <member>Konstantin Knizhnik</member>
    <member>Kuntal Ghosh</member>
    <member>Kyle Samson</member>
    <member>Kyotaro Horiguchi</member>
    <member>Lætitia Avrot</member>
    <member>Lars Kanis</member>
    <member>Laurenz Albe</member>
    <member>Leonardo Cecchi</member>
    <member>Liudmila Mantrova</member>
    <member>Lixian Zou</member>
    <member>Lloyd Albin</member>
    <member>Luca Ferrari</member>
    <member>Lucas Fairchild</member>
    <member>Lukas Eder</member>
    <member>Lukas Fittl</member>
    <member>Magnus Hagander</member>
    <member>Mai Peng</member>
    <member>Maksim Milyutin</member>
    <member>Maksym Boguk</member>
    <member>Mansur Galiev</member>
    <member>Marc Dilger</member>
    <member>Marco Nenciarini</member>
    <member>Marina Polyakova</member>
    <member>Mario de Frutos Dieguez</member>
    <member>Mark Cave-Ayland</member>
    <member>Mark Dilger</member>
    <member>Mark Wood</member>
    <member>Marko Tiikkaja</member>
    <member>Markus Winand</member>
    <member>Martín Marqués</member>
    <member>Masahiko Sawada</member>
    <member>Matheus Oliveira</member>
    <member>Matthew Stickney</member>
    <member>Metin Doslu</member>
    <member>Michael Banck</member>
    <member>Michael Meskes</member>
    <member>Michael Paquier</member>
    <member>Michail Nikolaev</member>
    <member>Mike Blackwell</member>
    <member>Minh-Quan Tran</member>
    <member>Mithun Cy</member>
    <member>Morgan Owens</member>
    <member>Nathan Bossart</member>
    <member>Nathan Wagner</member>
    <member>Neil Conway</member>
    <member>Nick Barnes</member>
    <member>Nicolas Thauvin</member>
    <member>Nikhil Sontakke</member>
    <member>Nikita Glukhov</member>
    <member>Nikolay Shaplov</member>
    <member>Noah Misch</member>
    <member>Noriyoshi Shinoda</member>
    <member>Oleg Bartunov</member>
    <member>Oleg Samoilov</member>
    <member>Oliver Ford</member>
    <member>Pan Bian</member>
    <member>Pascal Legrand</member>
    <member>Patrick Hemmer</member>
    <member>Patrick Krecker</member>
    <member>Paul Bonaud</member>
    <member>Paul Guo</member>
    <member>Paul Ramsey</member>
    <member>Pavan Deolasee</member>
    <member>Pavan Maddamsetti</member>
    <member>Pavel Golub</member>
    <member>Pavel Stehule</member>
    <member>Peter Eisentraut</member>
    <member>Peter Geoghegan</member>
    <member>Petr Jelínek</member>
    <member>Petru-Florin Mihancea</member>
    <member>Phil Florent</member>
    <member>Philippe Beaudoin</member>
    <member>Pierre Ducroquet</member>
    <member>Piotr Stefaniak</member>
    <member>Prabhat Sahu</member>
    <member>Pu Qun</member>
    <member>QL Zhuo</member>
    <member>Rafia Sabih</member>
    <member>Rahila Syed</member>
    <member>Rainer Orth</member>
    <member>Rajkumar Raghuwanshi</member>
    <member>Raúl Marín Rodríguez</member>
    <member>Regina Obe</member>
    <member>Richard Yen</member>
    <member>Robert Haas</member>
    <member>Robins Tharakan</member>
    <member>Rod Taylor</member>
    <member>Rushabh Lathia</member>
    <member>Ryan Murphy</member>
    <member>Sahap Asci</member>
    <member>Samuel Horwitz</member>
    <member>Scott Ure</member>
    <member>Sean Johnston</member>
    <member>Shao Bret</member>
    <member>Shay Rojansky</member>
    <member>Shubham Barai</member>
    <member>Simon Riggs</member>
    <member>Simone Gotti</member>
    <member>Sivasubramanian Ramasubramanian</member>
    <member>Stas Kelvich</member>
    <member>Stefan Kaltenbrunner</member>
    <member>Stephen Froehlich</member>
    <member>Stephen Frost</member>
    <member>Steve Singer</member>
    <member>Steven Winfield</member>
    <member>Sven Kunze</member>
    <member>Taiki Kondo</member>
    <member>Takayuki Tsunakawa</member>
    <member>Takeshi Ideriha</member>
    <member>Tatsuo Ishii</member>
    <member>Tatsuro Yamada</member>
    <member>Teodor Sigaev</member>
    <member>Thom Brown</member>
    <member>Thomas Kellerer</member>
    <member>Thomas Munro</member>
    <member>Thomas Reiss</member>
    <member>Tobias Bussmann</member>
    <member>Todd A. Cook</member>
    <member>Tom Kazimiers</member>
    <member>Tom Lane</member>
    <member>Tomas Vondra</member>
    <member>Tomonari Katsumata</member>
    <member>Torsten Grust</member>
    <member>Tushar Ahuja</member>
    <member>Vaishnavi Prabakaran</member>
    <member>Vasundhar Boddapati</member>
    <member>Victor Drobny</member>
    <member>Victor Wagner</member>
    <member>Victor Yegorov</member>
    <member>Vik Fearing</member>
    <member>Vinayak Pokale</member>
    <member>Vincent Lachenal</member>
    <member>Vitaliy Garnashevich</member>
    <member>Vitaly Burovoy</member>
    <member>Vladimir Baranoff</member>
    <member>Xin Zhang</member>
    <member>Yi Wen Wong</member>
    <member>Yorick Peterse</member>
    <member>Yugo Nagata</member>
    <member>Yuqi Gu</member>
    <member>Yura Sokolov</member>
    <member>Yves Goergen</member>
    <member>Zhou Digoal</member>
   </simplelist>
  </sect2>

 </sect1>
