<!-- doc/src/sgml/release-11.sgml -->
<!-- See header comment in release.sgml about typical markup -->

 <sect1 id="release-11">
  <title>Release 11</title>

  <formalpara>
   <title>Release date:</title>
   <para>2018-??-?? (CURRENT AS OF 2018-05-01)</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>
      Major improvements to partitioning:
      <itemizedlist>
       <listitem>
        <para>
         Partitioning by a hash key
        </para>
       </listitem>
       <listitem>
        <para>
         <command>UPDATE</command> statements that change a partition key
         now move affected rows to the appropriate partitions
        </para>
       </listitem>
       <listitem>
        <para>
         Improved <command>SELECT</command> query performance due to
         enhanced partition elimination during query processing and
         execution
        </para>
       </listitem>
       <listitem>
        <para>
         Support for <literal>PRIMARY KEY</literal>, <literal>FOREIGN
         KEY</literal>, indexes, and triggers on partitioned tables
        </para>
       </listitem>
      </itemizedlist>
     </para>
    </listitem>

    <listitem>
     <para>
      Improvements to parallelism:
      <itemizedlist>
       <listitem>
        <para>
         Parallelized hash joins
        </para>
       </listitem>
       <listitem>
        <para>
         Parallelized <command>CREATE INDEX</command> for B-tree indexes
        </para>
       </listitem>
       <listitem>
        <para>
         Parallelized <command>CREATE TABLE .. AS</command>,
         <command>CREATE MATERIALIZED VIEW</command>, and certain
         queries using <literal>UNION</literal>
        </para>
       </listitem>
      </itemizedlist>
     </para>
    </listitem>

    <listitem>
     <para>
      SQL stored procedures, with support for embedded transactions
     </para>
    </listitem>

    <listitem>
     <para>
      JIT compilation of some SQL code, including support for fast evaluation
      of expressions
     </para>
    </listitem>

    <listitem>
     <para>
      Window functions now support all 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>
      Channel binding for SCRAM authentication, to prevent potential
      man-in-the-middle attacks on database connections
     </para>
    </listitem>

    <listitem>
     <para>
      Many other useful performance improvements, including making
      <command>ALTER TABLE .. ADD COLUMN</command> with a
      non-null column default faster
     </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>
        Have <link
        linkend="app-pgdump"><application>pg_dump</application></link>
        dump all aspects of a database (Haribabu Kommi)
       </para>

       <para>
        Previously database attributes like
        <command>GRANT</command>/<command>REVOKE</command> permissions and
        <command>ALTER DATABASE SET</command> and <command>ALTER ROLE IN
        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 all
        database aspects.  <command>pg_dumpall -g</command> will
        now only output role and tablespace-related attributes.
        <application>pg_dumpall</application>'s 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 comments
        and security labels.
       </para>

       <para>
        <command>pg_dumpall --clean</command> now restores the "postgres"
        and "template1" databases with the original locale and encoding
        settings.
       </para>

       <para>
        A restore of <application>pg_dumpall</application> will now create
        databases with their original locale and encoding, and will fail if
        the creation fails.  Previously <command>CREATE DATABASE</command>
        would be dumped without such specifications if the database locale
        and encoding matched the old cluster's defaults.
       </para>

       <para>
        DID I GET EVERYTHING?
       </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>
<!--
2017-11-17 [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, and 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 _bytes_ were skipped.
       </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>
<!--
2018-03-27 [1944cdc98] libpq: PQhost to return active connected host or hostadd
-->

       <para>
        Have libpq's <link
        linkend="libpq-pqhost"><function>PQhost()</function></link>
        always return the actual connected host (Haribabu Kommi)
       </para>

       <para>
        Previously <function>PQhost()</function> often returned the
        supplied host parameters, which could contain several hosts.
        It will now also return the host's IP address if the host name was
        not supplied.  The same is true of <function>PQport()</function>,
        which now returns the actual port number, not the multiple supplied
        port numbers.
       </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>, have <varname>statement_timeout</varname>
        apply to each Execute message, not to all commands before Sync
        (Tatsuo Ishii, Andres Freund)
       </para>
      </listitem>

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

       <para>
        Remove <structfield>relhaspkey</structfield> column from system
        table <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 table <structname>pg_proc</structname>'s
        <structfield>proisagg</structfield> and
        <structfield>proiswindow</structfield> with
        <structfield>prokind</structfield> (Peter Eisentraut)
       </para>

       <para>
        This new column more clearly identifies functions, procedures,
        aggregates, and window functions.
       </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 on large object open, <link
        linkend="lo-open"><function>lo_open()</function></link>, not
        read/write (Tom Lane, Michael Paquier)
       </para>
      </listitem>

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

       <para>
        Remove deprecated contrib/adminpack functions
        <function>pg_file_read()</function>,
        <function>pg_file_length()</function>, and
        <function>pg_logfile_rotate()</function> (Stephen Frost)
       </para>

       <para>
        These functions are now present by default.  Old <link
        linkend="adminpack"><application>adminpack</application></link>
        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 index options names like ("FillFactor" = 50) were
        automatically lower-cased.  This quoted capitalization will now
        generate an error.
       </para>
      </listitem>

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

       <para>
        Remove server variable <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>

      <listitem>
<!--
Branch: master [6bdf1303b] Avoid wrong results for power() with NaN
-->

       <para>
        Consistently return <literal>NaN</literal> for
        <literal>NaN</literal> inputs to <function>power()</function>
        on older platforms (Tom Lane, Dang Minh Huong)
       </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>
<!--
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 could only happen at planning
        time, meaning many joins and prepared queries could not use
        partition elimination.
       </para>
      </listitem>

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

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

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

       <para>
        Allow updated rows to automatically move to new partitions based
        on the new row contents (Amit Khandekar)
       </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 can store rows that don't match any of the
        other defined partitions, and is searched accordingly.
       </para>
      </listitem>

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

       <para>
        Allow <literal>UNIQUE</literal> indexes on partitioned tables if
        the partition key guarantees uniqueness (&Aacute;lvaro Herrera,
        Amit Langote)
       </para>
      </listitem>

      <listitem>
<!--
2018-01-19 [8b08f7d48] Local partitioned indexes
-->

       <para>
        Allow indexes on a partitioned table to be automatically created
        in any child partitions (&Aacute;lvaro Herrera)
       </para>

       <para>
        The new command <link linkend="sql-alterindex"><command>ALTER
        INDEX ATTACH PARTITION</command></link> allows indexes to be
        attached to partitions.  This does not behave as a global index
        since the contents are private to each index.  WARN WHEN USING
        AN EXISTING INDEX?
       </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>
<!--
2018-04-06 [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 <application>postgres_fdw</application>
        foreign tables.
       </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 partitioned tables automatically creates
        triggers on all partition tables, and on newly-created ones.
        This also allows deferred unique constraints on partitioned tables.
       </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>
        Allow equality joins between partitioned tables with identically
        partitioned child tables to join the child tables 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>
        Perform aggregation on each partition, and then merge 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"><application>postgres_fdw</application></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 btree indexes to be built in parallel (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 option <link
        linkend="guc-parallel-leader-participation"><varname>parallel_leader_participation</varname></link>
        to control if the leader 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 worker sort activity to
        <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 indexes to <link
        linkend="sql-createindex"><literal>INCLUDE</literal></link> columns
        that are not part of the unique constraint but are available
        for index-only scans (Anastasia Lubennikova, Alexander Korotkov,
        Teodor Sigaev)
       </para>

       <para>
        This is also useful for including columns that don't have btree
        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>
        Remember the highest btree index page to optimize future
        monotonically increasing index additions (Pavan Deolasee, Peter
        Geoghegan)
       </para>
      </listitem>

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

       <para>
        Allow entire hash index pages to be scanned (Ashutosh Sharma)
       </para>

       <para>
        Previously for each hash index entry, we need to refind the scan
        position within the page.  This cuts down on lock/unlock traffic.
       </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.  ACCURATE?
       </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 <type>TEXT</type> prefix operator ^@ which is supported by
        SP-GiST (Ildus Kurbangaliev)
       </para>

       <para>
        This is similar to using <literal>LIKE</literal> 'word%' with
        btree indexes, but 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 the selection of the optimizer statistics'
        most-common-values (Jeff Janes, Dean Rasheed)
       </para>

       <para>
        Previously most-common-values (<acronym>MCV</acronym>) were
        chosen based on their significance compared to all column
        values.  Now, <acronym>MCV</acronym> are chosen based on their
        significance compared to the non-<acronym>MCV</acronym> values.
        This improves the statistics for uniform (fewer) and non-uniform
        (more) distributions.
       </para>
      </listitem>

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

       <para>
        Improve selectivity estimates for &gt;= and &lt;= when the
        constants are not common values (Tom Lane)
       </para>

       <para>
        Previously such cases used the same selectivity as &gt; and
        &lt;, respectively.  This change is particularly useful for
        <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>
        Optimize var = var to var <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 row count optimizer 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>
        Add optimizer selectivity costs for <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.
-->

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

       <para>
        Allow <link
        linkend="postgres-fdw"><application>postgres_fdw</application></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>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Monitoring</title>

     <itemizedlist>

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

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

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

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

       <para>
        Add <structfield>bgw_type</structfield> to the background worker
        C structure (Peter Eisentraut)
       </para>

       <para>
        This is displayed to the user in
        <structname>pg_stat_activity</structname>.<structfield>backend_type</structfield>
        and <application>ps</application> output.
       </para>
      </listitem>

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

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

       <para>
        Specifically,
        <structname>table_constraints</structname>.<structfield>enforced</structfield>,
        <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>.
       </para>

      </listitem>

      </itemizedlist>

     </sect5>
    </sect4>

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

     <itemizedlist>

      <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 libpq option to support channel binding when using <link
        linkend="auth-password"><acronym>SCRAM</acronym></link>
        authentication (Michael Paquier)
       </para>

       <para>
        While <acronym>SCRAM</acronym> always prevents the
        replay of transmitted hashed passwords in a later
        session, <acronym>SCRAM</acronym> with channel binding
        also prevents man-in-the-middle attacks.  The options are <link
        linkend="libpq-scram-channel-binding"><option>scram_channel_binding=tls-unique</option></link>
        and <option>scram_channel_binding=tls-server-end-point</option>.
       </para>
      </listitem>

      <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, "ldapsearchfilter" 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 ldaps
        (Thomas Munro)
       </para>

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

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

       <para>
        Improve <acronym>LDAP</acronym> logging of 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 default roles which control file system access (Stephen Frost)
       </para>

       <para>
        Specifically, the new roles are: <link
        linkend="default-roles-table"><literal>pg_read_server_files</literal></link>,
        <literal>pg_write_server_files</literal>,
        <literal>pg_execute_server_program</literal>.  These roles now also
        control who can use <command>COPY</command> and extension <link
        linkend="file-fdw"><application>file_fdw</application></link>.
        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, superusers were exclusively granted access to these
        functions.
       </para>

       <para>
        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"><application>postgres_fdw</application></link>
        tables (Robert Haas)
       </para>

       <para>
        <productname>PostgreSQL</productname> only allows superusers to
        access <application>postgres_fdw</application> 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 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 length before <acronym>TOAST</acronym>
        storage will be considered for new rows (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.
-->

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

       <para>
        The new unit is "B".  This is in addition to "kB", "MB", "GB"
        and "TB".
       </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 via initdb
        (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>
        No longer retain <acronym>WAL</acronym> that spans two checkpoints
        (Simon Riggs)
       </para>

       <para>
        The retention of <acronym>WAL</acronym> records for only one
        checkpoint is required.
       </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 heap pages checksums to be checked 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 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><link linkend="sql-window">Window Functions</link></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 window function features to complete SQL:2011 compliance
        (Oliver Ford, Tom Lane)
       </para>

       <para>
        Specifically, allow <literal>RANGE</literal> mode to use
        <literal>PRECEDING</literal> and <literal>FOLLOWING</literal> to
        specify peer groups with values 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>

    </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 a table rewrite (Andrew Dunstan,
        Serge Rielau)
       </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>, \d+ 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 finalization function (Tom Lane)
       </para>

       <para>
        This is useful for allowing 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 jsonb scalars to numeric and boolean data types
        (Anastasia Lubennikova)
       </para>

      </listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Functions</title>

    <itemizedlist>

      <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
        hours and minutes from <acronym>UTC</acronym> (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>
<!--
2018-01-09 [69c3936a1] Expression evaluation based aggregate transition invocat
-->

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

       <para>
        Add SQL 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>.  The new
        <command>ALTER</command>/<command>DROP ROUTINE</command> commands
        allows altering/dropping of procedures, functions, and aggregates.
       </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 to top-transaction-level
        <command>CALL</command>s or in nested PL/pgSQL DO and
        <command>CALL</command> blocks that only contain other PL/pgSQL
        <command>DO</command> and <command>CALL</command> blocks.
        ACCURATE?
       </para>
      </listitem>

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

       <para>
        Add the ability to define PL/pgSQL record types 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 <application>jsonb_plpython</application> 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 <application>jsonb_plperl</application> 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 and
        the libpq setting had no effect in that case.
       </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> action to the <literal>ECPG
        WHENEVER</literal> statement (Vinayak Pokale)
       </para>

       <para>
        This generates a C 'continue' 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 ecpg mode to enable Oracle Pro*C 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 \gdesc to display
        the column names and types of the query output (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 \if statement.
       </para>
      </listitem>

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

       <para>
        Add <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>
        Have psql \d+ always show the partition 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>
        Have <application>psql</application> report the proper user name
        before the password prompt (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 used in an empty buffer
        (Bruce Momjian)
       </para>

       <para>
        Also add hints of how to exit when <command>quit</command> and
        <command>exit</command> are used alone on a line in a non-empty
        buffer.  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>
        Have <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 customize tab completion queries based on the server version
        (Tom Lane)
       </para>

       <para>
        Previously tab completion queries could fail.
       </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> expressions 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 approximated 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>

       <para>
        IS IT CLEAR FROM THE DOCS THAT THE REPLICATION SLOT IS NOT
        TEMPORARY?
       </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 initdb
        <option>--allow-group-access</option> flag.  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 originally unsupported due to concerns over its 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 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
        partitions
(Rushabh Lathia)
       </para>

       <para>
        This is useful if the system to be loaded has different collation
        definitions or endianness, requiring the rows to be stored in
        different partitions.
       </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 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>
<!--
2018-01-21 [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>

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

       <para>
        Add support for <productname>ARMv8</productname> hardware
        <acronym>CRC</acronym> calculations (Yuqi Gu, Heikki
        Linnakangas, 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>
<!--
2018-03-03 [a351679c8] Trivial adjustments in preparation for bootstrap data co
2018-04-08 [372728b0d] Replace our traditional initial-catalog-data format with
2018-04-26 [a0854f107] Avoid parsing catalog data twice during BKI file constru
-->

       <para>
        Overhaul the way system tables are defined for bootstrap use
        (John Naylor)
       </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>
<!--
2017-10-04 [212e6f34d] Replace binary search in fmgr_isbuiltin with a lookup ar
-->

       <para>
        Speed up lookups of builtin function names matching oids (Andres
        Freund)
       </para>

       <para>
        The previous binary search now uses 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 access speed 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 system column
        <structname>pg_class</structname>.<structfield>reltuples</structfield>
        consistent (Tomas Vondra)
       </para>
      </listitem>

      <listitem>
<!--
2018-04-25 [46cda5bf7] Change pgindent/README to specify that we use perltidy v
-->

       <para>
        Update to use <application>perltidy</application> version
        <literal>20170521</literal> (Tom Lane)
       </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"><application>pg_prewarm</application></link>
        to restore the previous shared buffer contents on startup (Mithun
        Cy, Robert Haas)
       </para>

       <para>
        This is accomplished by having
        <application>pg_prewarm</application> store the shared buffer
        relation/offset values to disk occasionally during server operation
        and shutdown.
       </para>
      </listitem>

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

       <para>
        Add <link linkend="pgtrgm"><application>pgtrgm</application></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 on <link
        linkend="citext"><application>citext</application></link> extension
        columns that can be used by <literal>LIKE</literal> comparisons
        (Alexey Chernyshov)
       </para>

       <para>
        Specifically, indexes 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"><application>btree_gin</application></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"><application>cube</application></link>
        and <link linkend="seg"><application>seg</application></link>
        extensions using GiST indexes to perform index-only scans
        (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 ~&gt;
        operator (Alexander Korotkov)
       </para>

       <para>
        This is useful for KNN-GiST searches.  HOW?
       </para>
      </listitem>

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

       <para>
        Add Vietnamese letter detection to the <link
        linkend="unaccent"><application>unaccent</application></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"><application>amcheck</application></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"><application>adminpack</application></link>
        use the new default file system access roles (Stephen Frost)
       </para>

       <para>
        Previously only superusers could call adminpack 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>
        Increase  <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>
<!--
2018-04-05 [1fd869066] Install errcodes.txt for use by extensions.
-->

       <para>
        Install <filename>errcodes.txt</filename> to provide access to
        the error codes reported by <productname>PostgreSQL</productname>
        (Thomas Munro)
       </para>
      </listitem>

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

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

       <para>
        This was never intended to be supported.
       </para>
      </listitem>

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

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

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

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

       <para>
        This extension no longer served as 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>XXX</member>
   </simplelist>
  </sect2>

 </sect1>
