doc: complete adding XML markup to PG 14 relnotes

[pgsql.git] / doc / src / sgml / release-14.sgml

<!-- doc/src/sgml/release-14.sgml -->
<!-- See header comment in release.sgml about typical markup -->

 <sect1 id="release-14">
  <title>Release 14</title>

  <formalpara>
   <title>Release date:</title>
   <para>2021-??-?? (AS OF 2021-05-15)</para>
  </formalpara>

  <sect2>
   <title>Overview</title>

   <para>
    <productname>PostgreSQL</productname> 14 contains many new features and
    enhancements, including:
   </para>

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

   <para>
    The above items and other new features
    of <productname>PostgreSQL</productname> 14 are explained in more
    detail in the sections below.
   </para>

  </sect2>

  <sect2>

  <title>Migration to Version 14</title>

    <para>
     A dump/restore using <xref linkend="app-pg-dumpall"/> or use of <xref
     linkend="pgupgrade"/> or logical replication is required for those
     wishing to migrate data from any previous release.  See <xref
     linkend="upgrading"/> for general information on migrating to new major
     releases.
    </para>

    <para>
     Version 14 contains a number of changes that may affect compatibility
     with previous releases.  Observe the following incompatibilities:
    </para>

   <itemizedlist>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-08-08 [20e7e1fe3] Remove &lt;@ from contrib/intarray's GiST operator classes.
-->

<para>
Prevent the containment operators (&lt;@ and @&gt;) for <xref linkend="intarray"/> from using GiST indexes (Tom Lane)
</para>

<para>
Previously a full GiST index scan was required, so just avoid that and scan the heap, which is faster.  Indexes created for this purpose should be removed.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-11-03 [2f70fdb06] Remove deprecated containment operators for built-in typ
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-05 [112d411fb] Remove deprecated containment operators for contrib type
-->

<para>
Remove deprecated containment operators @ and ~ for built-in <link linkend="functions-geometry">geometric data types</link> and contrib modules <xref linkend="cube"/>, <xref linkend="hstore"/>,
<xref linkend="intarray"/>, and <xref linkend="seg"/> (Justin Pryzby)
</para>

<para>
The more consistent &lt;@ and @&gt; have been recommended for many years.
</para>
</listitem>

<listitem>
<!--
Author: Alexander Korotkov <akorotkov@postgresql.org>
2021-01-31 [0c4f355c6] Fix parsing of complex morphs to tsquery
-->

<para>
Fix <link linkend="functions-textsearch"><function>to_tsquery()</function></link> and <function>websearch_to_tsquery()</function> to properly parse query text containing discarded tokens (Alexander Korotkov)
</para>

<para>
Certain discarded tokens, like underscore, caused the output of these functions to produce incorrect tsquery output, e.g., both websearch_to_tsquery('"pg_class pg"') and to_tsquery('pg_class &lt;-&gt;
pg') used to output '( pg &amp; class ) &lt;-&gt; pg', but now both output 'pg &lt;-&gt; class &lt;-&gt; pg'.
</para>
</listitem>

<listitem>
<!--
Author: Alexander Korotkov <akorotkov@postgresql.org>
2021-05-03 [eb086056f] Make websearch_to_tsquery() parse text in quotes as a si
-->

<para>
Fix <link linkend="functions-textsearch"><function>websearch_to_tsquery()</function></link> to properly parse multiple adjacent discarded tokens in quotes (Alexander Korotkov)
</para>

<para>
Previously, quoted text that contained multiple adjacent discarded tokens were treated as multiple tokens, causing incorrect tsquery output, e.g., websearch_to_tsquery('"aaa: bbb"') used to output 
'aaa &lt;2&gt; bbb', but now  outputs 'aaa &lt;-&gt; bbb'.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-10 [c7eab0e97] Change default of password_encryption to scram-sha-256
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-10 [c7eab0e97] Change default of password_encryption to scram-sha-256
-->

<para>
Change the default of the <xref linkend="guc-password-encryption"/> server parameter to <literal>scram-sha-256</literal> (Peter Eisentraut)
</para>

<para>
Previously it was <literal>md5</literal>.  All new passwords will be stored as SHA256 unless this server variable is changed or the password is specified in md5 format.
Also, the legacy (and undocumented) boolean-like values which were previously synonyms for <literal>md5</literal> are no longer accepted.
</para>
</listitem>

<listitem>
<!--
Author: Bruce Momjian <bruce@momjian.us>
2020-10-05 [253f1025d] Overhaul pg_hba.conf clientcert's API
-->

<para>
Overhaul the specification of <literal>clientcert</literal> in <link linkend="auth-pg-hba-conf"><filename>pg_hba.conf</filename></link> (Kyotaro Horiguchi)
</para>

<para>
Values <literal>1</literal>/<literal>0</literal>/<literal>no-verify</literal> are no longer supported;  only the strings <literal>verify-ca</literal> and <literal>verify-full</literal> can be used.  Also, disallow <literal>verify-ca</literal> if cert
authentication is enabled since cert requires <literal>verify-full</literal> checking.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2021-03-09 [f9264d152] Remove support for SSL compression
Author: Michael Paquier <michael@paquier.xyz>
2021-03-10 [0ba71107e] Revert changes for SSL compression in libpq
-->

<para>
Remove support for <link linkend="runtime-config-connection-ssl"><acronym>SSL</acronym></link> compression (Daniel Gustafsson, Michael Paquier)
</para>

<para>
This was already disabled by default in previous Postgres releases, and most modern OpenSSL and <acronym>TLS</acronym> versions no longer support it.
</para>
</listitem>

<listitem>
<!--
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
2021-03-04 [3174d69fb] Remove server and libpq support for old FE/BE protocol v
-->

<para>
Remove server and <link linkend="libpq">libpq</link> support for the version 2 <link linkend="protocol">wire protocol</link> (Heikki Linnakangas)
</para>

<para>
This was last used as the default in Postgres 7.2 (year 2002).
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-04-06 [a2da77cdb] Change return type of EXTRACT to numeric
-->

<para>
Change <link linkend="functions-datetime"><function>EXTRACT</function></link> to return the <type>NUMERIC</type> data type (Peter Eisentraut)
</para>

<para>
<function>EXTRACT(date)</function> now throws an error for units that are not part of the date data type.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-20 [a4faef8f8] Fix some corner cases for window ranges with infinite of
-->

<para>
Fix handling of infinite <link linkend="syntax-window-functions">window function</link> ranges (Tom Lane)
</para>

<para>
Previously window frame clauses like <literal>'inf' PRECEDING AND 'inf' FOLLOWING</literal> returned incorrect results.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-11-25 [f73999262] tablefunc: Reject negative number of tuples passed to no
-->

<para>
Prevent <xref linkend="tablefunc"/>'s function <function>normal_rand()</function> from accepting negative values (Ashutosh Bapat)
</para>

<para>
Negative values produced undesirable results.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-06-13 [23cbeda50] Sync behavior of var_samp and stddev_samp for single NaN
-->

<para>
Change <link linkend="functions-aggregate"><function>var_samp()</function></link> and <function>stddev_samp()</function> with numeric parameters to return NULL for a single NaN value (Tom Lane)
</para>

<para>
Previously <literal>NaN</literal> was returned.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-17 [76f412ab3] Remove factorial operators, leaving only the factorial()
-->

<para>
Remove factorial operators <literal>!</literal> and <literal>!!</literal> (Mark Dilger)
</para>

<para>
The <link linkend="functions-math"><function>factorial()</function></link> function is still supported.  Also remove function <function>numeric_fac()</function>.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-18 [0a40563ea] Disallow factorial of negative numbers
-->

<para>
Disallow <function>factorial()</function> of negative numbers (Peter Eisentraut)
</para>

<para>
Previously such cases returned 1.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-17 [1ed6b8956] Remove support for postfix (right-unary) operators.
-->

<para>
Remove support for <link linkend="sql-createoperator">postfix</link> (right-unary) operators (Mark Dilger)
</para>

<para>
<application>pg_dump</application> and <application>pg_upgrade</application> will warn if postfix operators are being dumped.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-25 [7dc13a0f0] Change regex \D and \W shorthands to always match newlin
-->

<para>
Allow <literal>\D</literal> and <literal>\W</literal> shorthands to match newlines in <link linkend="functions-similarto-regexp">regular expression</link> newline-sensitive mode (Tom Lane)
</para>

<para>
Previously they did not match;  <literal>[^[:digit:]]</literal> or <literal>[^[:word:]]</literal> can be used to get the old behavior.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-02 [4aea704a5] Fix semantics of regular expression back-references.
-->

<para>
Improve handling of regular expression back-references (Tom Lane)
</para>

<para>
For example, disregard <literal>^</literal> in its expansion in <literal>\1</literal> in <literal>(^\d+).*\1</literal>.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-25 [2a0af7fe4] Allow complemented character class escapes within regex 
-->

<para>
Disallow <literal>\w</literal> as range start/end in character classes (Tom Lane)
</para>

<para>
This previously was allowed but produced incorrect results.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-07 [3db826bd5] Tighten up allowed names for custom GUC parameters.
-->

<para>
Require <link linkend="runtime-config-custom">custom server variable</link> names to match the pattern used for unquoted <acronym>SQL</acronym> identifiers (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2021-03-10 [9f3665fbf] Don't consider newly inserted tuples in nbtree VACUUM.
Author: Peter Geoghegan <pg@bowt.ie>
2021-03-11 [effdd3f3b] Add back vacuum_cleanup_index_scale_factor parameter.
-->

<para>
Remove server variable <varname>vacuum_cleanup_index_scale_factor</varname> (Peter Geoghegan)
</para>

<para>
This setting was ignored starting in <productname>PostgreSQL</productname> version 13.3.
</para>
</listitem>

<listitem>
<!--
Author: Joe Conway <mail@joeconway.com>
2021-03-31 [b12bd4869] Fix has_column_privilege function corner case
-->

<para>
Return false for <link linkend="functions-info"><function>has_column_privilege()</function></link> checks on non-existent or dropped columns when using attribute numbers (Joe Conway)
</para>

<para>
Previously such attribute numbers returned an invalid column error.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-10-22 [3dfb1942d] Avoid premature de-doubling of quote marks in ECPG strin
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-10-22 [c16a1bbcf] Add documentation and tests for quote marks in ECPG lite
-->

<para>
Pass doubled quote marks in <xref linkend="ecpg"/> <acronym>SQL</acronym> command strings literally (Tom Lane)
</para>

<para>
Previously <literal>'abc''def'</literal> was passed to the server as <literal>'abc'def'</literal>, and <literal>"abc""def"</literal> was passed as <literal>"abc"def"</literal>.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-11 [5333e014a] Remove deprecated syntax from CREATE/DROP LANGUAGE
-->

<para>
Disallow single-quoting of the language name in the <link linkend="sql-createlanguage"><command>CREATE/DROP LANGUAGE</command></link> command (Peter Eisentraut)
</para>
</listitem>

<listitem>
<!--
Author: Thomas Munro <tmunro@postgresql.org>
2021-01-29 [514b411a2] Retire pg_standby.
-->

<para>
Remove contrib program <application>pg_standby</application> (Justin Pryzby)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-07 [f3faf35f3] Don't create pg_type entries for sequences or toast tabl
-->

<para>
Remove <link linkend="xfunc-sql-composite-functions">composite types</link> for sequences or toast tables (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-12-08 [a676386b5] Remove operator_precedence_warning.
-->

<para>
Remove <varname>operator_precedence_warning</varname> setting (Tom Lane)
</para>

<para>
This was needed for warning applications about <productname>PostgreSQL</productname> 9.5 changes.
</para>
</listitem>

   </itemizedlist>

  </sect2>

  <sect2>
   <title>Changes</title>

     <para>
       Below you will find a detailed account of the changes between
       <productname>PostgreSQL</productname> 14 and the previous major
       release.
     </para>

   <sect3>
    <title>Server</title>

   <itemizedlist>

<listitem>
<!--
Author: Stephen Frost <sfrost@snowman.net>
2021-04-05 [6c3ffd697] Add pg_read_all_data and pg_write_all_data roles
-->

<para>
Add predefined roles <link linkend="predefined-roles"><structname>pg_read_all_data</structname></link> and <structname>pg_write_all_data</structname> (Stephen Frost)
</para>

<para>
These non-login roles give read-only/write-only access to all objects.
</para>
</listitem>

<listitem>
<!--
Author: Noah Misch <noah@leadboat.com>
2021-03-26 [a14a0118a] Add "pg_database_owner" default role.
-->

<para>
Add a predefined role to match the database owner (Noah Misch)
</para>

<para>
It is called <link linkend="predefined-roles"><literal>pg_database_owner</literal></link>; this is useful in template databases.
</para>
</listitem>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-03-18 [cd91de0d1] Remove temporary files after backend crash
-->

<para>
Remove temporary files after backend crashes (Euler Taveira)
</para>

<para>
These files were previously retained for debugging purposes;  deletion can be disabled with <xref linkend="guc-remove-temp-files-after-crash"/>.
</para>
</listitem>

<listitem>
<!--
Author: Thomas Munro <tmunro@postgresql.org>
2021-04-03 [c30f54ad7] Detect POLLHUP/POLLRDHUP while running queries.
-->

<para>
Allow long-running queries to be canceled if the client disconnects (Sergey Cherkashin, Thomas Munro)
</para>

<para>
The server variable <xref linkend="guc-client-connection-check-interval"/> allows some supported operating systems to automatically cancel queries by disconnected clients.
</para>
</listitem>

<listitem>
<!--
Author: Magnus Hagander <magnus@hagander.net>
2021-04-08 [aaf043257] Add functions to wait for backend termination
-->

<para>
Add function <link linkend="functions-admin-signal"><function>pg_wait_for_backend_termination()</function></link> that waits for session exit (Bharath Rupireddy)
</para>

<para>
Also add a similar optional wait parameter to <link linkend="functions-admin-signal"><function>pg_terminate_backend()</function></link>
</para>
</listitem>

<listitem>
<!--
Author: Noah Misch <noah@leadboat.com>
2021-03-30 [0ff8bbdee] Accept slightly-filled pages for tuples larger than fill
-->

<para>
Allow wide tuples to be always added to almost-empty heap pages (John Naylor, Floris van Nee)
</para>

<para>
Previously tuples whose insertion would have exceeded the page's <link linkend="sql-createtable">fill factor</link> were instead added to new pages.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-04-07 [5c55dc8b4] libpq: Set Server Name Indication (SNI) for SSL connecti
-->

<para>
Add Set Server Name Indication (<acronym>SNI</acronym>) for <acronym>SSL</acronym> connection packets (Peter Eisentraut)
</para>

<para>
This can be disabled by turning off client option <link linkend="libpq-paramkeywords"><literal>sslsni</literal></link>.
</para>
</listitem>

   </itemizedlist>

    <sect4>
     <title><link linkend="routine-vacuuming">Vacuuming</link></title>

     <itemizedlist>

<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2021-04-07 [5100010ee] Teach VACUUM to bypass unnecessary index vacuuming.
-->

<para>
Allow vacuum to skip index vacuuming when the number of removable index entries is insignificant (Masahiko Sawada, Peter Geoghegan)
</para>
</listitem>

<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2021-03-21 [9dd963ae2] Recycle nbtree pages deleted during same VACUUM.
-->

<para>
Allow vacuum to eagerly add newly deleted btree pages to the free space map (Peter Geoghegan)
</para>

<para>
Previously vacuum could only place preexisting deleted pages in the free space map.
</para>
</listitem>

<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2021-04-07 [3c3b8a4b2] Truncate line pointer array during VACUUM.
-->

<para>
Allow vacuum to deallocate space reserved by trailing unused heap line pointers (Matthias van de Meent, Peter Geoghegan)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-12-08 [e2ac3fed3] Speed up rechecking if relation needs to be vacuumed or 
-->

<para>
Speed up vacuuming of databases with many relations (Tatsuhito Kasahara)
</para>
</listitem>

<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2021-01-27 [e19594c5c] Reduce the default value of vacuum_cost_page_miss.
-->

<para>
Reduce the default value of <xref linkend="guc-vacuum-cost-page-miss"/> from 10 milliseconds to 2 (Peter Geoghegan)
</para>

<para>
This new default better reflects current hardware capabilities.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2021-02-09 [7cb3048f3] Add option PROCESS_TOAST to VACUUM
-->

<para>
Add ability to skip vacuuming of <acronym>TOAST</acronym> tables (Nathan Bossart)
</para>

<para>
<link linkend="sql-vacuum"><command>VACUUM</command></link> now has a <literal>PROCESS_TOAST</literal> which can be set to false to disable <acronym>TOAST</acronym> processing, and
<link linkend="app-vacuumdb"><application>vacuumdb</application></link> has a <option>--no-process-toast</option> option.
</para>
</listitem>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-01-17 [7db0cd214] Set PD_ALL_VISIBLE and visibility map bits in COPY FREEZ
-->

<para>
Have <link linkend="sql-copy"><command>COPY FREEZE</command></link> appropriately update page visibility bits (Anastasia Lubennikova, Pavan Deolasee, Jeff Janes)
</para>
</listitem>

<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2021-04-07 [1e55e7d17] Add wraparound failsafe to VACUUM.
-->

<para>
Cause vacuum operations to be aggressive if the table is near xid or multixact wraparound (Masahiko Sawada, Peter Geoghegan)
</para>

<para>
This is controlled by <xref linkend="guc-vacuum-failsafe-age"/> and <xref linkend="guc-multixact-failsafe-age"/>.
</para>
</listitem>

<listitem>
<!--
Author: Noah Misch <noah@leadboat.com>
2020-08-01 [cd5e82256] Change XID and mxact limits to warn at 40M and stop at 3
-->

<para>
Increase warning time and hard limit before transaction id and multi-transaction wraparound (Noah Misch)
</para>

<para>
This should reduce the possibility of failures that occur without having issued warnings about wraparound.
</para>
</listitem>

<listitem>
<!--
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
2021-04-08 [0827e8af7] autovacuum: handle analyze for partitioned tables
-->

<para>
<link linkend="autovacuum">Autovacuum</link> now analyzes partitioned tables (Yuzuko Hosoya, Álvaro Herrera)
</para>

<para>
Insert, update, and delete tuple counts from partitions are now propagated to their parent tables so autovacuum knows when to process them.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2021-03-23 [5aed6a1fc] Add per-index stats information in verbose logs of autov
-->

<para>
Add per-index information to <link linkend="guc-log-autovacuum-min-duration">autovacuum logging output</link> (Masahiko Sawada)
</para>
</listitem>

     </itemizedlist>
    </sect4>

    <sect4>
     <title><link linkend="ddl-partitioning">Partitioning</link></title>

     <itemizedlist>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-31 [86dc90056] Rework planning and execution of UPDATE and DELETE.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-06 [a1115fa07] Postpone some more stuff out of ExecInitModifyTable.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-06 [c5b7ba4e6] Postpone some stuff out of ExecInitModifyTable.
-->

<para>
Improve the performance of updates/deletes on partitioned tables when only a few partitions are affected (Amit Langote, Tom Lane)
</para>

<para>
This also allows updates/deletes on partitioned tables to use execution-time partition pruning.
</para>
</listitem>

<listitem>
<!--
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
2021-03-25 [71f4c8c6f] ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY
-->

<para>
Allow partitions to be <link linkend="sql-altertable">detached</link> in a non-blocking manner (Álvaro Herrera)
</para>

<para>
The syntax is <command>ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY</command>, and <command>FINALIZE</command>.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-28 [2dfa3fea8] Remove complaints about COLLATE clauses in partition bou
-->

<para>
Allow the arbitrary collations of partition boundary values (Tom Lane)
</para>

<para>
Previously it had to match the collation of the partition key.
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Indexes</title>

     <itemizedlist>

<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2021-01-13 [9dc718bdf] Pass down "logically unchanged index" hint.
Author: Peter Geoghegan <pg@bowt.ie>
2021-01-13 [d168b6668] Enhance nbtree index tuple deletion.
-->

<para>
Allow btree index additions to <link linkend="btree-deletion">remove expired index entries</link> to prevent page splits (Peter Geoghegan)
</para>

<para>
This is particularly helpful for reducing index bloat on tables whose indexed columns are frequently updated.
</para>
</listitem>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-03-26 [ab596105b] BRIN minmax-multi indexes
-->

<para>
Allow <link linkend="brin"><acronym>BRIN</acronym></link> indexes to record multiple min/max values per range (Tomas Vondra)
</para>

<para>
This is useful if there are groups of values in each page range.
</para>
</listitem>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-03-26 [77b88cd1b] BRIN bloom indexes
-->

<para>
Allow <acronym>BRIN</acronym> indexes to use bloom filters (Tomas Vondra)
</para>

<para>
This allows bloom indexes to be used effectively with data that is not physically localized in the heap.
</para>
</listitem>

<listitem>
<!--
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
2020-09-17 [16fa9b2b3] Add support for building GiST index by sorting.
-->

<para>
Allow some <link linkend="gist">GiST</link> indexes to be built by presorting the data (Andrey Borodin)
</para>

<para>
Presorting happens automatically and allows for faster index creation and smaller indexes.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-05 [09c1c6ab4] Support INCLUDE'd columns in SP-GiST.
-->

<para>
Allow <link linkend="spgist">SP-GiST</link> to use <literal>INCLUDE</literal>'d columns (Pavel Borisov)
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Optimizer</title>

     <itemizedlist>

<listitem>
<!--
Author: David Rowley <drowley@postgresql.org>
2021-04-08 [50e17ad28] Speedup ScalarArrayOpExpr evaluation
-->

<para>
Allow hash lookup of <literal>IN</literal> clause with many constants (James Coleman, David Rowley)
</para>

<para>
Previously the only option was to sequentially scan the list of constants.
</para>
</listitem>

<listitem>
<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2020-12-03 [25a9e54d2] Improve estimation of OR clauses using extended statisti
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2020-12-08 [88b0898fe] Improve estimation of OR clauses using multiple extended
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2020-12-08 [4f5760d4a] Improve estimation of ANDs under ORs using extended stat
-->

<para>
Increase the number of places <link linkend="planner-stats-extended">extended statistics</link> can be used for <literal>OR</literal> clause estimation (Tomas Vondra, Dean Rasheed)
</para>
</listitem>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-03-27 [a4d75c86b] Extended statistics on expressions
-->

<para>
Allow extended statistics on expressions (Tomas Vondra)
</para>

<para>
This allows statistics on a group of expressions and columns, rather than only columns like previously.  System view <link linkend="view-pg-stats-ext-exprs"><structname>pg_stats_ext_exprs</structname></link>
reports such statistics. <link linkend="sql-altertable"><literal>ALTER TABLE ... ALTER COLUMN ... TYPE RESETS STASTISTICS</literal></link>?
</para>
</listitem>

<listitem>
<!--
Author: David Rowley <drowley@postgresql.org>
2021-02-27 [bb437f995] Add TID Range Scans to support efficient scanning ranges
-->

<para>
Allow efficient heap scanning of a range of <link linkend="datatype-oid-table"><type>TIDs</type></link> (Edmund Horner, David Rowley)
</para>

<para>
Previously a sequential scan was required for non-equality <type>TID</type> specifications.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-12-30 [e665769e6] Sanitize IF NOT EXISTS in EXPLAIN for CTAS and matviews
-->

<para>
Fix <link linkend="sql-explain"><command>EXPLAIN CREATE TABLE AS</command></link> and <command>EXPLAIN CREATE MATERIALIZED VIEW</command> to honor <literal>IF NOT EXISTS</literal> (Bharath Rupireddy)
</para>

<para>
Previously, if the object already exists, <command>EXPLAIN</command> would fail.
</para>
</listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

<listitem>
<!--
Author: Andres Freund <andres@anarazel.de>
2020-08-12 [dc7420c2c] snapshot scalability: Don't compute global horizons whil
Author: Andres Freund <andres@anarazel.de>
2020-08-13 [1f51c17c6] snapshot scalability: Move PGXACT->xmin back to PGPROC.
Author: Andres Freund <andres@anarazel.de>
2020-08-14 [941697c3c] snapshot scalability: Introduce dense array of in-progre
Author: Andres Freund <andres@anarazel.de>
2020-08-14 [5788e258b] snapshot scalability: Move PGXACT->vacuumFlags to ProcGl
Author: Andres Freund <andres@anarazel.de>
2020-08-14 [73487a60f] snapshot scalability: Move subxact info to ProcGlobal, r
Author: Andres Freund <andres@anarazel.de>
2020-08-17 [623a9ba79] snapshot scalability: cache snapshots using a xact compl
-->

<para>
Improve the speed of computing <acronym>MVCC</acronym> <link linkend="mvcc">visibility snapshots</link> on systems with many CPUs and high session counts (Andres Freund)
</para>

<para>
This also improves performance when there are many idle sessions.
</para>
</listitem>

<listitem>
<!--
Author: David Rowley <drowley@postgresql.org>
2021-04-02 [9eacee2e6] Add Result Cache executor node (take 2)
-->

<para>
Add executor method to cache results from the inner-side of nested loop joins (David Rowley)
</para>

<para>
This is useful if only a small percentage of rows is checked on the inner side.
</para>
</listitem>

<listitem>
<!--
Author: David Rowley <drowley@postgresql.org>
2020-09-15 [62e221e1c] Allow incremental sorts for windowing functions
-->

<para>
Allow <link linkend="functions-window">window functions</link> to perform incremental sorts (David Rowley)
</para>
</listitem>

<listitem>
<!--
Author: David Rowley <drowley@postgresql.org>
2020-07-26 [56788d215] Allocate consecutive blocks during parallel seqscans
-->

<para>
Improve the I/O performance of parallel sequential scans (Thomas Munro, David Rowley)
</para>

<para>
This was done by allocating blocks in groups to <link linkend="guc-max-parallel-workers">parallel workers</link>.
</para>
</listitem>

<listitem>
<!--
Author: Etsuro Fujita <efujita@postgresql.org>
2021-03-31 [27e1f1456] Add support for asynchronous execution.
-->

<para>
Allow a query referencing multiple <link linkend="sql-createforeigntable">foreign tables</link> to perform foreign table scans in parallel (Robert Haas, Kyotaro Horiguchi, Thomas Munro, Etsuro Fujita)
</para>

<para>
The <link linkend="postgres-fdw"><application>postgres_fdw</application></link> supports these type of scans if <literal>async_capable</literal> is set.
</para>
</listitem>

<listitem>
<!--
Author: Stephen Frost <sfrost@snowman.net>
2021-03-16 [c6fc50cb4] Use pre-fetching for ANALYZE
-->

<para>
Allow <link linkend="vacuum-for-statistics">analyze</link> to do page prefetching (Stephen Frost)
</para>

<para>
This is controlled by <xref linkend="guc-maintenance-io-concurrency"/>.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-20 [08c0d6ad6] Invent "rainbow" arcs within the regex engine.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-20 [824bf7190] Recognize "match-all" NFAs within the regex engine.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-20 [cebc1d34e] Fix regex engine to suppress useless concatenation sub-R
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-20 [581043089] Convert regex engine's subre tree from binary to N-ary s
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-20 [ea1268f63] Avoid generating extra subre tree nodes for capturing pa
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-21 [190c79884] Simplify memory management for regex DFAs a little.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-26 [0fc1af174] Improve memory management in regex compiler.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-02 [0c3405cf1] Improve performance of regular expression back-reference
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-02 [4604f83fd] Suppress unnecessary regex subre nodes in a couple more 
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-08 [6c20bdb2a] Further tweak memory management for regex DFAs.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-05-03 [f68970e33] Fix performance issue in new regex match-all detection c
-->

<para>
Improve the performance of <link linkend="functions-similarto-regexp">regular expression</link> comparisons (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-10-11 [80f8eb79e] Use perfect hash for NFC and NFKC Unicode Normalization 
Author: Michael Paquier <michael@paquier.xyz>
2020-10-23 [783f0cc64] Improve performance of Unicode {de,re}composition in the
-->

<para>
Dramatically improve Unicode normalization (John Naylor)
</para>

<para>
This speeds <link linkend="functions-string"><function>normalize()</function></link> and <literal>IS NORMALIZED</literal>.
</para>
</listitem>

<listitem>
<!--
Author: Robert Haas <rhaas@postgresql.org>
2021-03-19 [bbe0a81db] Allow configurable LZ4 TOAST compression.
-->

<para>
Add ability to use <link linkend="sql-createtable">LZ4 compression</link> on <acronym>TOAST</acronym> data (Dilip Kumar)
</para>

<para>
This can be set at the column level, or set as a default via server setting <xref linkend="guc-default-toast-compression"/>.  The server must be compiled with <link linkend="configure-options-features"><option>--with-lz4</option></link> to support this feature;  the default is still pglz.
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>Monitoring</title>

     <itemizedlist>

<listitem>
<!--
Author: Bruce Momjian <bruce@momjian.us>
2021-04-07 [4f0b0966c] Make use of in-core query id added by commit 5fd9dfa5f5
Author: Bruce Momjian <bruce@momjian.us>
2021-04-07 [f57a2f5e0] Add csvlog output for the new query_id value
Author: Bruce Momjian <bruce@momjian.us>
2021-04-20 [9660834dd] adjust query id feature to use pg_stat_activity.query_id
Author: Bruce Momjian <bruce@momjian.us>
2021-05-03 [f7a97b6ec] Update query_id computation
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
2021-05-15 [cafde58b3] Allow compute_query_id to be set to 'auto' and make it d
-->

<para>
If server variable <xref linkend="guc-compute-query-id"/> is enabled, display the query id in <link linkend="monitoring-pg-stat-activity-view"><structname>pg_stat_activity</structname></link>,
<link linkend="sql-explain"><command>EXPLAIN VERBOSE</command></link>, <link linkend="runtime-config-logging">csvlog</link>, and optionally in <xref linkend="guc-log-line-prefix"/>
(Julien Rouhaud)
</para>

<para>
A query id computed by an extension will also be displayed.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-08-19 [3e98c0baf] Add pg_backend_memory_contexts system view.
Author: Fujii Masao <fujii@postgresql.org>
2020-08-26 [29dd6d8bc] Prevent non-superusers from reading pg_backend_memory_co
-->

<para>
Add system view <link linkend="view-pg-backend-memory-contexts"><structname>pg_backend_memory_contexts</structname></link> to report session memory usage (Atsushi Torikoshi, Fujii Masao)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-04-06 [43620e328] Add function to log the memory contexts of specified bac
-->

<para>
Add function <link linkend="functions-admin-signal"><function>pg_log_backend_memory_contexts()</function></link> to output the memory contexts of arbitrary backends (Atsushi Torikoshi)
</para>
</listitem>

<listitem>
<!--
Author: Stephen Frost <sfrost@snowman.net>
2021-03-16 [94d13d474] Improve logging of auto-vacuum and auto-analyze
-->

<para>
Improve logging of <link linkend="autovacuum">auto-vacuum</link> and auto-analyze (Stephen Frost, Jakub Wartak)
</para>

<para>
This reports I/O timings for auto-vacuum and auto-analyze if <xref linkend="guc-track-io-timing"/> is enabled.  Also, report buffer read and dirty rates for auto-analyze.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2021-04-07 [9afffcb83] Add some information about authenticated identity via lo
-->

<para>
Add information about the original user name supplied by the client to the output of <xref linkend="guc-log-connections"/> (Jacob Champion)
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4>
     <title>System Views</title>

     <itemizedlist>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-01-06 [8a4f618e7] Report progress of COPY commands
Author: Michael Paquier <michael@paquier.xyz>
2021-03-09 [9d2d45700] Add support for more progress reporting in COPY
-->

<para>
Add view <link linkend="copy-progress-reporting"><structname>pg_stat_progress_copy</structname></link> to report <command>COPY</command> progress (Josef Šimánek, Matthias van de Meent)
</para>
</listitem>

<listitem>
<!--
Author: Magnus Hagander <magnus@hagander.net>
2021-01-17 [960869da0] Add pg_stat_database counters for sessions and session t
-->

<para>
Add session statistics to the <link linkend="monitoring-pg-stat-database-view"><structname>pg_stat_database</structname></link> system view (Laurenz Albe)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-07-20 [d05b172a7] Add generic_plans and custom_plans fields into pg_prepar
-->

<para>
Add columns to <link linkend="view-pg-prepared-statements"><structname>pg_prepared_statements</structname></link> to report generic and custom plan counts (Atsushi Torikoshi, Kyotaro Horiguchi)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-02-15 [46d6e5f56] Display the time when the process started waiting for th
-->

<para>
Add lock wait start time to <link linkend="view-pg-locks"><structname>pg_locks</structname></link> (Atsushi Torikoshi)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-10-02 [8d9a93596] Add pg_stat_wal statistics view.
Author: Fujii Masao <fujii@postgresql.org>
2020-12-02 [01469241b] Track total number of WAL records, FPIs and bytes genera
Author: Fujii Masao <fujii@postgresql.org>
2021-03-09 [ff99918c6] Track total amounts of times spent writing and syncing W
-->

<para>
Add system view <link linkend="monitoring-pg-stat-wal-view"><structname>pg_stat_wal</structname></link> which reports <acronym>WAL</acronym> activity (Masahiro Ikeda)
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2020-10-08 [986816750] Track statistics for spilling of changes from ReorderBuf
Author: Amit Kapila <akapila@postgresql.org>
2020-10-20 [03d51b776] Change the attribute name in pg_stat_replication_slots v
Author: Amit Kapila <akapila@postgresql.org>
2020-10-29 [8e90ec558] Track statistics for streaming of changes from ReorderBu
Author: Amit Kapila <akapila@postgresql.org>
2021-04-16 [f5fc2f5b2] Add information of total data processed to replication s
-->

<para>
Add system view <link linkend="monitoring-pg-stat-replication-slots-view"><structname>pg_stat_replication_slots</structname></link> to report replication slot activity (Sawada Masahiko, Amit Kapila, Vignesh C)
</para>

<para>
Function <link linkend="monitoring-stats-functions"><function>pg_stat_reset_replication_slot()</function></link> resets slot statistics.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-14 [f560209c6] Make walsenders show their replication commands in pg_st
-->

<para>
Improve <link linkend="monitoring-pg-stat-activity-view"><structname>pg_stat_activity</structname></link> reporting of walsender processes (Tom Lane)
</para>

<para>
Previously only <acronym>SQL</acronym> commands were reported.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-03-15 [d75288fb2] Make archiver process an auxiliary process.
-->

<para>
Make the archiver process visible in <structname>pg_stat_activity</structname> (Kyotaro Horiguchi)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-03-24 [84007043f] Rename wait event WalrcvExit to WalReceiverExit.
-->

<para>
Add wait event <link linkend="monitoring-pg-stat-activity-view"><literal>WalReceiverExit</literal></link> to report <acronym>WAL</acronym> receiver exit wait time (Fujii Masao)
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-02-17 [f40c6969d] Routine usage information schema tables
-->

<para>
Implement information schema view <link linkend="infoschema-routine-column-usage"><structname>routine_column_usage</structname></link> to track columns referenced by function and procedure default expressions (Peter Eisentraut)
</para>
</listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

<listitem>
<!--
Author: Andrew Dunstan <andrew@dunslane.net>
2021-03-29 [6d7a6feac] Allow matching the DN of a client certificate for authen
-->

<para>
Allow the certificate's distinguished name (<acronym>DN</acronym>) to be matched for client certificate authentication (Andrew Dunstan)
</para>

<para>
The new <link linkend="auth-pg-hba-conf"><filename>pg_hba.conf</filename></link> keyword <literal>clientname=DN</literal> allows comparison with certificate attributes beyond the <literal>CN</literal> and can be combined with ident maps.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-03 [8f8154a50] Allow records to span multiple lines in pg_hba.conf and 
-->

<para>
Allow <filename>pg_hba.conf</filename> and <link linkend="auth-username-maps"><filename>pg_ident.conf</filename></link> records to span multiple lines (Fabien Coelho)
</para>

<para>
A backslash at the end of a line allows record contents to be continued on the next line.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-02-18 [f5465fade] Allow specifying CRL directory
-->

<para>
Allow the specification of a certificate revocation list (<acronym>CRL</acronym>) directory (Kyotaro Horiguchi)
</para>

<para>
This is controlled by server variable <xref linkend="guc-ssl-crl-dir"/> and libpq connection option sslcrldir.  Previously only <acronym>CRL</acronym> files could be specified.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-03 [67a472d71] Remove arbitrary restrictions on password length.
-->

<para>
Allow passwords of an arbitrary length (Tom Lane, Nathan Bossart)
</para>
</listitem>

     </itemizedlist>

    </sect4>

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

     <itemizedlist>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-01-06 [9877374be] Add idle_session_timeout.
-->

<para>
Add server setting <xref linkend="guc-idle-session-timeout"/> to close idle sessions (Li Japin)
</para>

<para>
This is similar to <xref linkend="guc-idle-in-transaction-session-timeout"/>.
</para>
</listitem>

<listitem>
<!--
Author: Stephen Frost <sfrost@snowman.net>
2021-03-24 [bbcc4eb2e] Change checkpoint_completion_target default to 0.9
-->

<para>
Change <xref linkend="guc-checkpoint-completion-target"/> default to 0.9 (Stephen Frost)
</para>

<para>
The previous default was 0.5.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-08-03 [b8fdee7d0] Add %P to log_line_prefix for parallel group leader
-->

<para>
Allow %P in <xref linkend="guc-log-line-prefix"/> to report the parallel group leader (Justin Pryzby)
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-11-07 [a05dbf477] Add GUC_LIST_INPUT and GUC_LIST_QUOTE to unix_socket_dir
-->

<para>
Allow <xref linkend="guc-unix-socket-directories"/> to specify paths as individual, comma-separated quoted strings (Ian Lawrence Barwick)
</para>

<para>
Previously all the paths had to be in a single quoted string.
</para>
</listitem>

<listitem>
<!--
Author: Thomas Munro <tmunro@postgresql.org>
2020-07-31 [84b1c63ad] Preallocate some DSM space at startup.
-->

<para>
Allow startup allocation of dynamic shared memory (Thomas Munro)
</para>

<para>
This is controlled by <xref linkend="guc-min-dynamic-shared-memory"/>.   This allows more use of huge pages.
</para>
</listitem>

<listitem>
<!--
Author: Thomas Munro <tmunro@postgresql.org>
2020-07-17 [d2bddc250] Add huge_page_size setting for use on Linux.
-->

<para>
Add setting <xref linkend="guc-huge-page-size"/> to control the size of huge pages used on Linux (Odin Ugedal)
</para>
</listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

<listitem>
<!--
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
2020-11-12 [9c4f5192f] Allow pg_rewind to use a standby server as the source sy
-->

<para>
Allow standby servers to be rewound via <link linkend="app-pgrewind"><application>pg_rewind</application></link> (Heikki Linnakangas)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-12-02 [942305a36] Allow restore_command parameter to be changed with reloa
-->

<para>
Allow <xref linkend="guc-restore-command"/> setting to be changed during a server reload (Sergei Kornilov)
</para>

<para>
You can also set <varname>restore_command</varname> to an empty string and reload to force recovery to only read from the <link linkend="storage-file-layout"><filename>pg_wal</filename></link> directory.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-01-08 [0650ff230] Add GUC to log long wait times on recovery conflicts.
Author: Fujii Masao <fujii@postgresql.org>
2021-01-13 [39b03690b] Log long wait time on recovery conflict when it's resolv
-->

<para>
Add server variable <xref linkend="guc-log-recovery-conflict-waits"/> to report long recovery conflict wait times (Bertrand Drouvot, Masahiko Sawada)
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-01-18 [15251c0a6] Pause recovery for insufficient parameter settings
-->

<para>
Pause recovery if the primary changes its parameters in a way that prevents replay on the hot standby (Peter Eisentraut)
</para>

<para>
Previously the standby would shut down immediately.
</para>
</listitem>

<listitem>
<!--
Author: Robert Haas <rhaas@postgresql.org>
2021-03-11 [32fd2b57d] Be clear about whether a recovery pause has taken effect
-->

<para>
Add function <link linkend="functions-recovery-control"><function>pg_get_wal_replay_pause_state()</function></link> to report the recovery state (Dilip Kumar)
</para>

<para>
It gives more detailed information than <link linkend="functions-recovery-control"><function>pg_is_wal_replay_paused()</function></link>, which still exists.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-01-05 [bf8a662c9] Introduce a new GUC_REPORT setting "in_hot_standby".
-->

<para>
Add new server-side variable <xref linkend="guc-in-hot-standby"/> (Haribabu Kommi, Greg Nancarrow, Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2021-01-12 [d6ad34f34] Optimize DropRelFileNodeBuffers() for recovery.
-->

<para>
Speed truncation of small tables during recovery on clusters with a large number of shared buffers (Kirk Jamison)
</para>
</listitem>

<listitem>
<!--
Author: Thomas Munro <tmunro@postgresql.org>
2021-03-20 [61752afb2] Provide recovery_init_sync_method=syncfs.
-->

<para>
Allow file system sync at the start of crash recovery on Linux (Thomas Munro)
</para>

<para>
By default, Postgres opens and fsyncs every data file at the start of crash recovery.
This new setting, <xref linkend="guc-recovery-init-sync-method"/><literal>=syncfs</literal>, instead syncs each filesystem used by the database cluster.
This allows for faster recovery on systems with many database files.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-07-12 [b1e48bbe6] Include replication origins in SQL functions for commit 
-->

<para>
Add function <link linkend="functions-info"><function>pg_xact_commit_timestamp_origin()</function></link> to return the commit timestamp and replication origin of the specified transaction (Movead Li)
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-07-12 [b1e48bbe6] Include replication origins in SQL functions for commit 
-->

<para>
Add the replication origin to the record returned by <link linkend="functions-info"><function>pg_last_committed_xact()</function></link> (Movead Li)
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-06-14 [cc072641d] Replace superuser check by ACLs for replication origin f
-->

<para>
Allow replication <link linkend="functions-replication">origin functions</link> to be controlled using standard function permission controls (Martín Marqués)
</para>

<para>
Previously these functions could only be executed by super-users, and this is still the default.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-11-16 [2945a488a] Make the standby server promptly handle interrupt signal
OTHER COMMITS
-->

<para>
Improve signal handling reliability (Fujii Masao)
</para>

<para>
GENERAL ENOUGH?
</para>
</listitem>

    </itemizedlist>

    <sect4>
     <title><link linkend="logical-replication">Logical Replication</link></title>

     <itemizedlist>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2020-09-03 [464824323] Add support for streaming to built-in logical replicatio
Author: Amit Kapila <akapila@postgresql.org>
2020-12-30 [0aa8a01d0] Extend the output plugin API to allow decoding of prepar
Author: Amit Kapila <akapila@postgresql.org>
2021-01-04 [a271a1b50] Allow decoding at prepare time in ReorderBuffer.
Author: Amit Kapila <akapila@postgresql.org>
2020-08-08 [7259736a6] Implement streaming mode in ReorderBuffer.
-->

<para>
Allow logical replication to stream long in-progress transactions to subscribers (Tomas Vondra, Dilip Kumar, Amit Kapila, Ajin Cherian, Nikhil Sontakke, Stas Kelvich)
</para>

<para>
Previously transactions that exceeded <xref linkend="guc-logical-decoding-work-mem"/> were written to disk until the transaction completed.
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2020-07-28 [45fdc9738] Extend the logical decoding output plugin API with strea
-->

<para>
Enhance the logical replication <acronym>API</acronym> to allow streaming large in-progress transactions (Tomas Vondra, Dilip Kumar, Amit Kapila)
</para>

<para>
The output functions begin with <link linkend="logicaldecoding-output-plugin-stream-start"><literal>stream</literal></link>.  <application>test_decoding</application> also supports these.
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2021-02-12 [ce0fdbfe9] Allow multiple xacts during table sync in logical replic
-->

<para>
Allow multiple transactions during table sync in logical replication (Peter Smith, Amit Kapila, and Takamichi Osumi)
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2020-07-20 [0bead9af4] Immediately WAL-log subtransaction and top-level XID ass
-->

<para>
Immediately <acronym>WAL</acronym>-log subtransaction and top-level <type>XID</type> association (Tomas Vondra, Dilip Kumar, Amit Kapila)
</para>

<para>
This is useful for logical decoding.
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2020-12-30 [0aa8a01d0] Extend the output plugin API to allow decoding of prepar
Author: Amit Kapila <akapila@postgresql.org>
2021-01-04 [a271a1b50] Allow decoding at prepare time in ReorderBuffer.
Author: Amit Kapila <akapila@postgresql.org>
2021-03-03 [19890a064] Add option to enable two_phase commits via pg_create_log
-->

<para>
Enhance logical decoding APIs to handle two-phase commits (Ajin Cherian, Amit Kapila, Nikhil Sontakke, Stas Kelvich)
</para>

<para>
This is controlled via <link linkend="functions-replication"><function>pg_create_logical_replication_slot()</function></link>.
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2020-07-23 [c55040ccd] WAL Log invalidations at command end with wal_level=logi
-->

<para>
Generate <acronym>WAL</acronym> invalidations message during command completion when using logical replication (Dilip Kumar, Tomas Vondra, Amit Kapila)
</para>

<para>
When logical replication is disabled, <acronym>WAL</acronym> invalidation messages are generated at transaction completion.  This allows logical streaming of in-progress transactions.
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2020-10-15 [d7eb52d71] Execute invalidation messages for each XLOG_XACT_INVALID
-->

<para>
Allow logical decoding to more efficiently process cache invalidation messages (Dilip Kumar)
</para>

<para>
This allows <link linkend="logicaldecoding">logical decoding</link> to work efficiently in presence of a large amount of <acronym>DDL</acronym>.
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2021-04-06 [ac4645c01] Allow pgoutput to send logical decoding messages.
-->

<para>
Allow control over whether logical decoding messages are sent to the replication stream (David Pirotte, Euler Taveira)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-18 [9de77b545] Allow logical replication to transfer data in binary for
-->

<para>
Allow logical replication subscriptions to use binary transfer mode (Dave Cramer)
</para>

<para>
This is faster than text mode, but slightly less robust.
</para>
</listitem>

<listitem>
<!--
Author: Amit Kapila <akapila@postgresql.org>
2021-03-30 [f64ea6dc5] Add a xid argument to the filter_prepare callback for ou
-->

<para>
Allow logical decoding to be filtered by xid (Markus Wanner)
</para>
</listitem>

     </itemizedlist>
    </sect4>

   </sect3>

   <sect3>
    <title><link linkend="sql-select"><command>SELECT</command></link>, <link linkend="sql-insert"><command>INSERT</command></link></title>

    <itemizedlist>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-18 [06a7c3154] Allow most keywords to be used as column labels without 
-->

<para>
Reduce the number of keywords that can't be used as column labels without <literal>AS</literal> (Mark Dilger)
</para>

<para>
There are now 90% fewer restricted keywords.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-03-31 [055fee7eb] Allow an alias to be attached to a <literal>JOIN ... USING</literal>
-->

<para>
Allow an alias to be specified for <literal>JOIN</literal>'s <literal>USING</literal> clause (Peter Eisentraut)
</para>

<para>
The alias is created by using <literal>AS</literal> after the <literal>USING</literal> clause and represents an alias for the <literal>USING</literal> columns.
</para>
</listitem>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-03-18 [be45be9c3] Implement GROUP BY DISTINCT
-->

<para>
Allow <literal>DISTINCT</literal> to be added to <literal>GROUP BY</literal> to remove duplicate <literal>GROUPING SET</literal> combinations (Vik Fearing)
</para>

<para>
For example, <literal>GROUP BY CUBE (a,b), CUBE (b,c)</literal> will generate duplicate grouping combinations without <literal>DISTINCT</literal>.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-22 [17958972f] Allow a multi-row <command>INSERT</command> to specify DEFAULTs for a gener
-->

<para>
Properly handle <literal>DEFAULT</literal> values for columns in multi-column inserts (Dean Rasheed)
</para>

<para>
This used to throw an error.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-02-01 [3696a600e] SEARCH and CYCLE clauses
Author: Peter Eisentraut <peter@eisentraut.org>
2021-02-27 [f4adc41c4] Enhanced cycle mark values
-->

<para>
Add <acronym>SQL</acronym>-standard <literal>SEARCH</literal> and <literal>CYCLE</literal> clauses for <link linkend="queries-with">common table expressions</link> (Peter Eisentraut)
</para>

<para>
This could be accomplished previously using existing syntax.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-13 [6c0373ab7] Allow table-qualified variable names in ON CONFLICT ... 
-->

<para>
Allow the <literal>WHERE</literal> clause of <literal>ON CONFLICT</literal> to be table-qualified (Tom Lane)
</para>

<para>
Only the target table can be referenced.
</para>
</listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

<listitem>
<!--
Author: Thomas Munro <tmunro@postgresql.org>
2021-03-17 [9e7ccd9ef] Enable parallelism in REFRESH MATERIALIZED VIEW.
-->

<para>
Allow <link linkend="sql-refreshmaterializedview"><command>REFRESH MATERIALIZED VIEW</command></link> to use parallelism (Bharath Rupireddy)
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2021-02-04 [c5b286047] Add TABLESPACE option to REINDEX
-->

<para>
Allow <link linkend="sql-reindex"><command>REINDEX</command></link> to change the tablespace of the new index (Alexey Kondratov, Michael Paquier, Justin Pryzby)
</para>

<para>
This is done by specifying a <literal>TABLESPACE</literal> clause.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-09-08 [a6642b3ae] Add support for partitioned tables and indexes in REINDE
-->

<para>
Allow <command>REINDEX</command> to process all child tables or indexes of a partitioned relation (Justin Pryzby, Michael Paquier)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-25 [0a0727ccf] Improve performance of binary COPY FROM through better b
-->

<para>
Improve the performance of <link linkend="sql-copy"><command>COPY FROM</command></link> in binary mode (Bharath Rupireddy, Amit Langote)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-04 [40c24bfef] Improve our ability to regurgitate SQL-syntax function c
-->

<para>
Preserve <acronym>SQL</acronym> standard syntax in <link linkend="sql-createview">view definitions</link>, if possible (Tom Lane)
</para>

<para>
Previously non-function call <acronym>SQL</acronym> standard syntax, e.g. <link linkend="functions-formatting"><function>EXTRACT</function></link>, were converted to non-<acronym>SQL</acronym> standard function calls.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-01-30 [6aaaa76bb] Allow GRANTED BY clause in normal GRANT and REVOKE state
-->

<para>
Add the <acronym>SQL</acronym>-standard clause <literal>GRANTED BY</literal> to <link linkend="sql-grant"><command>GRANT</command></link> and <link linkend="sql-revoke"><command>REVOKE</command></link> (Peter Eisentraut)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-14 [92bf7e2d0] Provide the OR REPLACE option for CREATE TRIGGER.
-->

<para>
Add <literal>OR REPLACE</literal> for <link linkend="sql-createtrigger"><command>CREATE TRIGGER</command></link> (Takamichi Osumi)
</para>

<para>
This allows pre-existing triggers to be conditionally replaced.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-04-08 [8ff1c9464] Allow TRUNCATE command to truncate foreign tables.
-->

<para>
Allow <link linkend="sql-truncate"><command>TRUNCATE</command></link> to operate on foreign tables (Kazutaka Onishi, Kohei KaiGai)
</para>

<para>
The <link linkend="postgres-fdw"><application>postgres_fdw</application></link> module also now supports this.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-04-06 [82ed7748b] ALTER SUBSCRIPTION ... ADD/DROP PUBLICATION
-->

<para>
Allow publications to be more easily added and removed (Japin Li)
</para>

<para>
The new syntax is <link linkend="sql-altersubscription"><command>ALTER SUBSCRIPTION ... ADD/DROP PUBLICATION</command></link>.  This avoids having to specify all publications to add/remove entries.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-01-30 [dfb75e478] Add primary keys and unique constraints to system catalo
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-02 [62f34097c] Build in some knowledge about foreign-key relationships 
-->

<para>
Add primary keys, unique constraints, and foreign keys to <link linkend="catalogs">system catalogs</link> (Peter Eisentraut)
</para>

<para>
This helps <acronym>GUI</acronym> tools analyze the system tables.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-09-17 [45b980570] Allow CURRENT_ROLE where CURRENT_USER is accepted
-->

<para>
Allow <link linkend="functions-info"><literal>CURRENT_ROLE</literal></link> every place <literal>CURRENT_USER</literal> is accepted (Peter Eisentraut)
</para>
</listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-12-09 [c7aba7c14] Support subscripting of arbitrary types, not only arrays
-->

<para>
Allow extensions and built-in data types to implement <link linkend="sql-altertype">subscripting</link> (Dmitry Dolgov)
</para>

<para>
Previously subscript handling was hard-coded into the server, so that subscripting could only be applied to array types.  This change allows subscript notation to be used to extract or
assign portions of a value of any type for which the concept makes sense.
</para>
</listitem>

<listitem>
<!--
Author: Alexander Korotkov <akorotkov@postgresql.org>
2021-01-31 [676887a3b] Implementation of subscripting for jsonb
Author: Alexander Korotkov <akorotkov@postgresql.org>
2021-01-31 [81fcc72e6] Filling array gaps during jsonb subscripting
Author: Alexander Korotkov <akorotkov@postgresql.org>
2021-01-31 [aa6e46daf] Throw error when assigning jsonb scalar instead of a com
-->

<para>
Allow subscripting of <link linkend="datatype-json"><type>JSONB</type></link> (Dmitry Dolgov)
</para>

<para>
<type>JSONB</type> subscripting can be used to extract and assign to portions of <type>JSONB</type> documents.
</para>
</listitem>

<listitem>
<!--
Author: Author: Alexander Korotkov <akorotkov@postgresql.org>
2020-12-20 [6df7a9698] Multirange datatypes
Author: Alexander Korotkov <akorotkov@postgresql.org>
2020-12-29 [db6335b5b] Add support of multirange matching to the existing range
Author: Alexander Korotkov <akorotkov@postgresql.org>
2020-12-30 [62097a4cc] Fix selectivity estimation @&gt; (anymultirange, anyrange)
-->

<para>
Add support for <link linkend="rangetypes">multirange data types</link> (Paul Jungwirth, Alexander Korotkov)
</para>

<para>
These are like range data types, but they allow the specification of multiple, ordered, non-overlapping ranges.
All existing range types now also support multirange versions.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-23 [0cc993278] Rename the "point is strictly above/below point" compari
-->

<para>
Add <link linkend="functions-geometry">point operators</link> &lt;&lt;| and |&gt;&gt; to be strictly above/below geometry (Emre Hasegeli)
</para>

<para>
Previously &gt;^ and &lt;^ were marked as performing this test, but non-point geometric operators used these operators for non-strict comparisons, leading to confusion.  The old operators still exist but will be eventually removed.  ACCURATE?
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-08 [cbcc8726b] Update snowball
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-08 [c2e71cb35] Update documentation for snowball update
Author: Peter Eisentraut <peter@eisentraut.org>
2021-02-19 [678d0e239] Update snowball
-->

<para>
Add support for the <link linkend="textsearch-snowball-dictionary">stemming</link> of languages Armenian, Basque, Catalan, Hindi, Serbian, and Yiddish (Peter Eisentraut)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-23 [83b61319a] Improve behavior of tsearch_readline(), and remove t_rea
-->

<para>
Allow <link linkend="textsearch-intro-configurations">tsearch data files</link> to have unlimited line lengths (Tom Lane)
</para>

<para>
The previous limit was 4k bytes.  Also remove function <function>t_readline()</function>.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-22 [a57d312a7] Support infinity and -infinity in the numeric data type.
-->

<para>
Add support for infinity and <literal>-infinity</literal> values to the <link linkend="datatype-numeric">numeric data type</link> (Tom Lane)
</para>

<para>
Floating point data types already supported these.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-21 [8597a48d0] Fix FPeq() and friends to get the right answers for infi
-->

<para>
Improve the accuracy of floating point computations involving infinity (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-04 [fac83dbd6] Remove underflow error in float division with infinite d
-->

<para>
Have non-zero <link linkend="datatype-float">float values</link> divided by infinity return zero (Kyotaro Horiguchi)
</para>

<para>
Previously such operations produced underflow errors.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-20 [4fb6aeb4f] Make floating-point "NaN / 0" return NaN instead of rais
-->

<para>
Cause floating-point division of NaN by zero to return NaN (Tom Lane)
</para>

<para>
Previously this returned an error.  Division with Numerics always returned NaN.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-06-30 [9bae7e4cd] Add +(pg_lsn,numeric) and -(pg_lsn,numeric) operators.
-->

<para>
Add operators to add and subtract <link linkend="datatype-pg-lsn"><type>LSN</type></link> and numeric (byte) values (Fujii Masao)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-21 [670c0a1d4] Weaken type-OID-matching checks in array_recv and record
-->

<para>
Allow <link linkend="protocol-format-codes">binary data transfer</link> to be more forgiving of array and record <type>OID</type> mismatches (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-06 [f7f70d5e2] Create composite array types for initdb-created relation
-->

<para>
Create composite array types for most system relations (Wenjing Zeng)
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Functions</title>

    <itemizedlist>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-04-07 [e717a9a18] SQL-standard function body
-->

<para>
Allow <acronym>SQL</acronym>-language <link linkend="sql-createfunction">functions</link> and <link linkend="sql-createprocedure">procedures</link> to use <acronym>SQL</acronym>-standard function bodies (Peter Eisentraut)
</para>

<para>
Previously only single-quoted or $$-quoted function bodies were supported.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-10-05 [2453ea142] Support for OUT parameters in procedures
Author: Peter Eisentraut <peter@eisentraut.org>
2020-10-27 [9213462c5] Make procedure OUT parameters work with JDBC
-->

<para>
Allow <link linkend="sql-createprocedure">procedures</link> to have <literal>OUT</literal> parameters (Peter Eisentraut)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-04 [9e38c2bb5] Declare assorted array functions using anycompatible not
-->

<para>
Allow some array functions to operate on a mix of compatible data types (Tom Lane)
</para>

<para>
The functions are <link linkend="functions-array"><function>array_append()</function></link>, <function>array_prepend()</function>, <function>array_cat()</function>, <function>array_position()</function>,
<function>array_positions()</function>, <function>array_remove()</function>, <function>array_replace()</function>, and
<link linkend="functions-math"><function>width_bucket()</function></link>.  Previously only identical data types could be used.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-03 [0a687c8f1] Add trim_array() function.
-->

<para>
Add <acronym>SQL</acronym>-standard <link linkend="functions-array"><function>trim_array()</function></link> function (Vik Fearing)
</para>

<para>
This can already be done with array slices.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-01-18 [a6cf3df4e] Add bytea equivalents of ltrim() and rtrim().
-->

<para>
Add bytea equivalents of <link linkend="functions-binarystring"><function>ltrim()</function></link> and <function>rtrim()</function> (Joel Jacobson)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-13 [ec0294fb2] Support negative indexes in split_part().
-->

<para>
Support negative indexes in <link linkend="functions-string"><function>split_part()</function></link> (Nikhil Benesch)
</para>

<para>
Negative values start from the last field and count backward.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-02 [66f163068] Add string_to_table() function.
-->

<para>
Add <link linkend="functions-string"><function>string_to_table()</function></link> function to split a string on delimiters (Pavel Stehule)
</para>

<para>
This is similar to the <link linkend="functions-string"><function>regexp_split_to_table()</function></link> function.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-03-29 [f37fec837] Add unistr function
-->

<para>
Add <link linkend="functions-string"><function>unistr()</function></link> function to allow Unicode characters to be specified as backslash-hex escapes in strings (Pavel Stehule)
</para>

<para>
This is similar to how Unicode can be specified in literal string.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-03-06 [f9a0392e1] Add bit_xor aggregate function
-->

<para>
Add <link linkend="functions-aggregate"><function>bit_xor()</function></link> XOR aggregate function (Alexey Bashtanov)
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-03-23 [a6715af1e] Add bit_count SQL function
-->

<para>
Add function <link linkend="functions-binarystring"><function>bit_count()</function></link> to return the number of bits set in a bit or byte string (David Fetter)
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-03-24 [49ab61f0b] Add date_bin function
Author: Peter Eisentraut <peter@eisentraut.org>
2021-04-10 [496e58bb0] Improve behavior of date_bin with origin in the future
-->

<para>
Add <link linkend="functions-datetime-bin"><function>date_bin()</function></link> function (John Naylor)
</para>

<para>
The function <function>date_bin()</function> "bins" the input timestamp into a specified interval aligned with a specified origin.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-29 [a094c8ff5] Fix make_timestamp[tz] to accept negative years as meani
-->

<para>
Allow <link linkend="functions-datetime"><function>make_timestamp()</function></link>/<function>make_timestamptz()</function> to accept negative years (Peter Eisentraut)
</para>

<para>
They are interpreted as <literal>BC</literal> years.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-29 [78c887679] Add current substring regular expression syntax
-->

<para>
Add newer regular expression <link linkend="functions-string"><function>substring()</function></link> syntax (Peter Eisentraut)
</para>

<para>
The new syntax is <literal>SUBSTRING(text SIMILAR pattern ESCAPE escapechar)</literal>.  The previous standard syntax was <literal>SUBSTRING(text FROM pattern FOR escapechar)</literal>, and is still supported by Postgres.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-25 [2a0af7fe4] Allow complemented character class escapes within regex 
-->

<para>
Allow complemented character class escapes <link linkend="posix-escape-sequences">\D</link>, <literal>\S</literal>, and <literal>\W</literal> within regex brackets (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-02-25 [2a0af7fe4] Allow complemented character class escapes within regex 
-->

<para>
Add <link linkend="posix-escape-sequences"><literal>[[:word:]]</literal></link> as a character class to match \w (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-11-04 [5c292e6b9] Declare lead() and lag() using anycompatible not anyelem
-->

<para>
Allow more flexible data types for default values of <link linkend="functions-window"><function>lead()</function></link> and <function>lag()</function> window functions (Vik Fearing)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-06-14 [decbe2bfb] Fix behavior of exp() and power() for infinity inputs.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-06-15 [e532b1d57] Fix power() for infinity inputs some more.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-06-15 [5674eb987] Fix power() for large inputs yet more.
-->

<para>
Cause <link linkend="functions-math"><function>exp()</function></link> and <function>power()</function> for negative-infinity exponents to return zero (Tom Lane)
</para>

<para>
Previously they often returned underflow errors.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-07-25 [8a37951ee] Mark built-in coercion functions as leakproof where poss
-->

<para>
Mark built-in type coercion functions as leakproof where possible (Tom Lane)
</para>

<para>
This allows more use of functions that require type conversion in security-sensitive situations.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-08 [fed10d4ee] Properly mark pg_stat_get_subscription() as returning a 
-->

<para>
Mark <function>pg_stat_get_subscription()</function> as returning a set (Tom Lane)
</para>

<para>
While it worked in previous releases, it didn't report proper optimizer statistics and couldn't be used in the target list.  FUNCTION NOT DOCUMENTED.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-01-13 [5a6f9bce8] Mark inet_server_addr() and inet_server_port() as parall
-->

<para>
Prevent <link linkend="functions-info"><function>inet_server_addr()</function></link> and <function>inet_server_port()</function> from being run by parallel workers (Masahiko Sawada)
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-07-15 [2a10fdc43] Eliminate cache lookup errors in SQL functions for objec
-->

<para>
Change <link linkend="functions-info"><function>pg_describe_object()</function></link>, <function>pg_identify_object()</function>, and 
<function>pg_identify_object_as_address()</function> to always report helpful error messages for non-existent objects (Michael Paquier)
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title><link linkend="plpgsql">PL/pgSQL</link></title>

    <itemizedlist>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-01-04 [c9d529848] Re-implement pl/pgsql's expression and assignment parsin
-->

<para>
Improve PL/pgSQL's <link linkend="plpgsql-expressions">expression</link> and <link linkend="plpgsql-statements-assignment">assignment</link> parsing (Tom Lane)
</para>

<para>
This adds nested record and array slicing support.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-06-12 [2f48ede08] Avoid using a cursor in plpgsql's RETURN QUERY statement
-->

<para>
Allow plpgsql's <link linkend="plpgsql-control-structures"><literal>RETURN QUERY</literal></link> to execute its query using parallelism (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-01-25 [ee895a655] Improve performance of repeated CALLs within plpgsql pro
-->

<para>
Improve performance of repeated <link linkend="plpgsql-transactions">CALL</link>s within plpgsql procedures (Pavel Stehule, Tom Lane)
</para>
</listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

<listitem>
<!--
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
2021-03-15 [acb7e4eb6] Implement pipeline mode in libpq
-->

<para>
Add <link linkend="libpq-pipeline-sending">pipeline</link> mode to libpq (Craig Ringer, Matthieu Garrigues, Álvaro Herrera)
</para>

<para>
This allows multiple queries to be sent and only wait for completion when a specific synchronization message is sent.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-02 [d16f8c8e4] Mark default_transaction_read_only as GUC_REPORT.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-02 [ee28cacf6] Extend the abilities of libpq's target_session_attrs par
-->

<para>
Enhance libpq's <link linkend="libpq-paramkeywords"><option>target_session_attrs</option></link> parameter options (Haribabu Kommi, Greg Nancarrow, Vignesh C, Tom Lane)
</para>

<para>
New options are <literal>read-only</literal>, <literal>primary</literal>, <literal>standby</literal>, and <literal>prefer-standby</literal>.
</para>
</listitem>

<listitem>
<!--
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
2021-03-30 [198b3716d] Improve PQtrace() output format
-->

<para>
Improve the output format of libpq's <link linkend="libpq-control"><function>PQtrace()</function></link> (Aya Iwata, Álvaro Herrera)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-22 [c0cb87fbb] Remove arbitrary line length limit for libpq service fil
-->

<para>
Allow the libpq <link linkend="libpq-pgservice">service file</link> to have unlimited line lengths (Daniel Gustafsson)
</para>

<para>
The previous limit was 255 bytes.
</para>
</listitem>

<listitem>
<!--
Author: Michael Meskes <meskes@postgresql.org>
2021-03-24 [ad8305a43] Add DECLARE STATEMENT command to ECPG
-->

<para>
Allow an <literal>ECPG SQL</literal> identifier to be linked to a specific connection (Hayato Kuroda)
</para>

<para>
This is done via <link linkend="ecpg-sql-declare-statement"><literal>DECLARE ... STATEMENT</literal></link>.
</para>
</listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2021-03-03 [57e6db706] Add - -tablespace option to reindexdb
-->

<para>
Allow <link linkend="app-reindexdb"><application>reindexdb</application></link> to change the tablespace of the new index (Michael Paquier)
</para>

<para>
This is done by specifying <option>--tablespace</option>.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-06-22 [9550ea302] Add - -no-index-cleanup and - -no-truncate to vacuumdb.
-->

<para>
Allow <link linkend="app-vacuumdb"><application>vacuumdb</application></link> to skip index cleanup and truncation (Nathan Bossart)
</para>

<para>
The options are <option>--no-index-cleanup</option> and <option>--no-truncate</option>.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2021-03-31 [6568cef26] Add support for - -extension in pg_dump
-->

<para>
Allow <link linkend="app-pgdump"><application>pg_dump</application></link> to dump only certain extensions (Guillaume Lelarge)
</para>

<para>
This is controlled by option <option>--extension</option>.
</para>
</listitem>

<listitem>
<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2021-04-06 [6b258e3d6] pgbench: Function to generate random permutations.
-->

<para>
Add <link linkend="pgbench"><application>pgbench</application></link> <function>permute()</function> function to randomly shuffle values (Fabien Coelho, Hironobu Suzuki, Dean Rasheed)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-09-17 [99175141c] Improve common/logging.c's support for multiple verbosit
-->

<para>
Allow multiple verbose option specifications (<option>-v</option>) to increase the logging verbosity (Tom Lane)
</para>

<para>
This is now supported by <link linkend="app-pgdump"><application>pg_dump</application></link>, <link linkend="app-pg-dumpall"><application>pg_dumpall</application></link>, 
and <link linkend="app-pgrestore"><application>pg_restore</application></link>.
</para>
</listitem>

    </itemizedlist>

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

     <itemizedlist>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-07 [a3027e1e7] Allow psql's \df and \do commands to specify argument ty
-->

<para>
Allow <application>psql</application>'s \df and \do commands to specify function and operator argument types (Greg Sabino Mullane, Tom Lane)
</para>

<para>
This helps reduce the number of matches for overloaded entries.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-09-02 [07f386ede] Add access method names to \d[i|m|t]+ in psql
-->

<para>
Add an access method column to <application>psql</application>'s \d[i|m|t]+ output (Georgios Kokolatos)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-01-05 [7d80441d2] Allow psql's \dt and \di to show TOAST tables and their 
-->

<para>
Allow <application>psql</application>'s \dt and \di to show <acronym>TOAST</acronym> tables and their indexes (Justin Pryzby)
</para>
</listitem>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-01-20 [ad600bba0] psql \dX: list extended statistics objects
-->

<para>
Add <application>psql</application> command \dX to list extended statistics objects (Tatsuro Yamada)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-07 [a3027e1e7] Allow psql's \df and \do commands to specify argument ty
-->

<para>
Fix <application>psql</application>'s \dT to understand array syntax and backend grammar aliases, like "int" for "integer" (Greg Sabino Mullane, Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-03 [55873a00e] Improve psql's behavior when the editor is exited withou
-->

<para>
When editing the previous query or a file with <application>psql</application>'s \e, or using \ef and \ev, ignore the contents if the editor exits without saving (Laurenz Albe)
</para>

<para>
Previously, such edits would still execute the editor contents.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-10-22 [94929f1cf] Clean up some unpleasant behaviors in psql's \connect co
-->

<para>
Improve <application>psql</application>'s handling of \connect with <option>-reuse-previous</option> (Tom Lane)
</para>

<para>
Specifically, properly reuse the password previously specified, and prompt for a new password if the previous one failed.
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-07-21 [c273d9d8c] Rework tab completion of COPY and \copy in psql
Author: Michael Paquier <michael@paquier.xyz>
2020-07-30 [f1af75c5f] Include partitioned tables for tab completion of VACUUM 
Author: Michael Paquier <michael@paquier.xyz>
2020-08-11 [1f75b4541] Improve tab completion of REINDEX in psql
Author: Michael Paquier <michael@paquier.xyz>
2020-09-17 [7307df16a] Improve tab completion of IMPORT FOREIGN SCHEMA in psql
Author: Fujii Masao <fujii@postgresql.org>
2020-09-28 [0baf82fa0] Improve tab-completion for DEALLOCATE.
Author: Michael Paquier <michael@paquier.xyz>
2020-10-24 [0b46e82c0] Add tab completion for ALTER TABLE .. FORCE ROW LEVEL SE
Author: Michael Paquier <michael@paquier.xyz>
2020-11-18 [bf0aa7c4b] Add tab completion for CREATE [OR REPLACE] TRIGGER in ps
Author: Fujii Masao <fujii@postgresql.org>
2021-01-14 [3f238b882] Improve tab-completion for CLOSE, DECLARE, FETCH and MOV
Author: Thomas Munro <tmunro@postgresql.org>
2021-02-05 [e1c02d92a] Tab-complete CREATE DATABASE ... LOCALE.
Author: Michael Paquier <michael@paquier.xyz>
2021-02-17 [e6b8e83b9] Add psql completion for [ NO ] DEPENDS ON EXTENSION
Author: Thomas Munro <tmunro@postgresql.org>
2021-02-23 [5bc09a747] Tab-complete CREATE COLLATION.
Author: Fujii Masao <fujii@postgresql.org>
2021-02-25 [6b40d9bdb] Improve tab-completion for TRUNCATE.
Author: Michael Paquier <michael@paquier.xyz>
2021-03-19 [5b2266e33] Improve tab completion of IMPORT FOREIGN SCHEMA with \h 
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-04-08 [d1fcbde57] Add support for tab-completion of type arguments in \df,
Author: Fujii Masao <fujii@postgresql.org>
2021-04-12 [81e094bdf] Support tab-complete for TRUNCATE on foreign tables.
Author: Michael Paquier <michael@paquier.xyz>
2021-04-21 [22b2dec31] Add CURRENT_ROLE to list of roles for tab completion of 
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
2021-04-26 [6dd1042ed] psql: tab-complete ALTER ... DETACH CONCURRENTLY / FINAL
Author: Michael Paquier <michael@paquier.xyz>
2021-05-13 [1906cc07d] Make saner the tab completion of INSERT and DELETE in ps
-->

<para>
Improve tab completion (Vignesh C, Michael Paquier, Justin Pryzby, Georgios Kokolatos, Julien Rouhaud, ADD NAMES)
</para>
</listitem>

     </itemizedlist>

    </sect4>

   </sect3>

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

    <itemizedlist>

<listitem>
<!--
Author: Robert Haas <rhaas@postgresql.org>
2021-03-12 [970609283] Add pg_amcheck, a CLI for contrib/amcheck.
-->

<para>
Add command-line utility <link linkend="app-pgamcheck"><application>pg_amcheck</application></link> to simplify running contrib/amcheck operations on many relations (Mark Dilger)
</para>
</listitem>

<listitem>
<!--
Author: Magnus Hagander <magnus@hagander.net>
2021-01-17 [e09155bd6] Add - -no-instructions parameter to initdb
-->

<para>
Add <option>--no-instructions</option> option to <link linkend="app-initdb"><application>initdb</application></link> (Magnus Hagander)
</para>

<para>
This removes the server start instructions that are normally output.
</para>
</listitem>

<listitem>
<!--
Author: Magnus Hagander <magnus@hagander.net>
2020-11-09 [8f113698b] Remove analyze_new_cluster script from pg_upgrade
-->

<para>
Stop <link linkend="pgupgrade"><application>pg_upgrade</application></link> from creating <filename>analyze_new_cluster</filename> script (Michael Paquier)
</para>

<para>
Instead, give comparable <link linkend="app-vacuumdb"><application>vacuumdb</application></link> instructions.
</para>
</listitem>

<listitem>
<!--
Author: Magnus Hagander <magnus@hagander.net>
2020-11-10 [d2e4bf688] Remove -o option to postmaster
-->

<para>
Remove support for the <link linkend="app-postgres"><application>postmaster</application></link> <option>-o</option> option (Magnus Hagander)
</para>

<para>
This option was unnecessary since all passed options could already be specified directly.
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Documentation</title>

    <itemizedlist>

<listitem>
<!--
Author: Stephen Frost <sfrost@snowman.net>
2021-04-01 [c9c41c7a3] Rename Default Roles to Predefined Roles
-->

<para>
Rename "Default Roles" to <link linkend="predefined-roles">"Predefined Roles"</link> (Bruce Momjian, Stephen Frost)
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-16 [4c5cf5431] doc: Document factorial function
-->

<para>
Add documentation for the <link linkend="function-factorial"><function>factorial()</function></link> function (Peter Eisentraut)
</para>

<para>
With the removal of the ! operator in this release, <function>factorial()</function> is the only built-in way to compute a factorial.
</para>
</listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2021-02-01 [fe61df7f8] Introduce - -with-ssl={openssl} as a configure option
-->

<para>
Add configure option <link linkend="configure-options-features"><literal>--with-ssl={openssl}</literal></link> to behave like <option>--with-openssl</option> (Daniel Gustafsson, Michael Paquier)
</para>

<para>
The option <option>--with-openssl</option> is kept for compatibility.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-11-25 [c9f0624bc] Add support for abstract Unix-domain sockets
-->

<para>
Add support for <link linkend="guc-unix-socket-directories">abstract Unix-domain sockets</link> (Peter Eisentraut)
</para>

<para>
This is currently supported on <productname>Linux</productname> and <productname>Windows</productname>.
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-01-06 [4656e3d66] Replace CLOBBER_CACHE_ALWAYS with run-time GUC
-->

<para>
Add <xref linkend="guc-debug-invalidate-system-caches-always"/> to control cache overwriting (Craig Ringer)
</para>

<para>
Previously this could only be controlled at compile time and is enabled only in assert builds.
</para>
</listitem>

<listitem>
<!--
Author: Peter Geoghegan <pg@bowt.ie>
2020-07-17 [1e0dfd166] Add Valgrind buffer access instrumentation.
Author: Peter Geoghegan <pg@bowt.ie>
2020-07-19 [46ef520b9] Mark buffers as defined to Valgrind consistently.
Author: Peter Geoghegan <pg@bowt.ie>
2020-07-19 [a766d6ca2] Avoid harmless Valgrind no-buffer-pin errors.
-->

<para>
Various improvements in <productname>valgrind</productname> detection (Álvaro Herrera, Peter Geoghegan)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-01-06 [ca8217c10] Add a test module for the regular expression package.
-->

<para>
Add a test module for the regular expression package (Tom Lane)
</para>
</listitem>

<listitem>
<!--
Author: Andres Freund <andres@anarazel.de>
2020-11-09 [6c57f2ed1] jit: Add support for LLVM 12.
-->

<para>
Add support for <productname>LLVM</productname> version 12 (Andres Freund)
</para>
</listitem>

<listitem>
<!--
Author: Michael Paquier <michael@paquier.xyz>
2020-12-04 [4f48a6fbe] Change SHA2 implementation based on OpenSSL to use EVP d
Author: Michael Paquier <michael@paquier.xyz>
2020-12-10 [b67b57a96] Refactor MD5 implementations according to new cryptohash
Author: Michael Paquier <michael@paquier.xyz>
2021-01-23 [a8ed6bb8f] Introduce SHA1 implementations in the cryptohash infrast
Author: Michael Paquier <michael@paquier.xyz>
2021-04-03 [e6bdfd970] Refactor HMAC implementations
-->

<para>
Change SHA1, SHA2, and MD5 hash computations to use the <productname>OpenSSL</productname> <acronym>EVP API</acronym> (Michael Paquier)
</para>

<para>
This is more modern and supports <acronym>FIPS</acronym> mode.
</para>
</listitem>

<listitem>
<!--
Author: Magnus Hagander <magnus@hagander.net>
2020-11-20 [16f96c74d] Remove ability to independently select random number gen
-->

<para>
Remove build control over the random library used (Daniel Gustafsson)
</para>
</listitem>

<listitem>
<!--
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
2021-01-28 [6c5576075] Add direct conversion routines between EUC_TW and Big5.
-->

<para>
Add direct conversion routines between EUC_TW and Big5 (Heikki Linnakangas)
</para>
</listitem>

<listitem>
<!--
Author: Thomas Munro <tmunro@postgresql.org>
2020-11-20 [ca051d8b1] Add collation versions for FreeBSD.
-->

<para>
Add collation versions for <productname>FreeBSD</productname> (Thomas Munro)
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-08-01 [9f9682783] Invent "amadjustmembers" AM method for validating opclas
-->

<para>
Add <link linkend="index-api"><structfield>amadjustmembers</structfield></link> to the index access method <acronym>API</acronym> (Tom Lane)
</para>

<para>
REMOVE?
</para>
</listitem>

    </itemizedlist>

   </sect3>

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

    <itemizedlist>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2020-12-11 [0ec5f7e78] Allow subscripting of hstore values.
-->

<para>
Allow subscripting of <link linkend="hstore"><application>hstore</application></link> values (Tom Lane, Dmitry Dolgov)
</para>
</listitem>

<listitem>
<!--
Author: Alexander Korotkov <akorotkov@postgresql.org>
2020-11-15 [935f66665] Handle equality operator in contrib/pg_trgm
-->

<para>
Allow GiST/GIN <link linkend="pgtrgm"><application>pg_trgm</application></link> indexes to do equality lookups (Julien Rouhaud)
</para>

<para>
This is similar to <literal>LIKE</literal> except no wildcards are honored.
</para>
</listitem>

<listitem>
<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2021-03-06 [1265a9c8f] Add binary I/O capability for cube datatype.
-->

<para>
Allow the <link linkend="cube"><application>cube</application></link> data type to be transferred in binary mode (KaiGai Kohei)
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2020-06-30 [ee0202d55] pgstattuple: Have pgstattuple_approx accept TOAST tables
-->

<para>
Allow <function>pgstattuple_approx()</function> to report on <acronym>TOAST</acronym> tables (Peter Eisentraut)
</para>
</listitem>

<listitem>
<!--
Author: Robert Haas <rhaas@postgresql.org>
2020-09-10 [34a947ca1] New contrib module, pg_surgery, with heap surgery functi
-->

<para>
Add contrib module <link linkend="pgsurgery"><application>pg_surgery</application></link> which allows changes to row visibility (Ashutosh Sharma)
</para>

<para>
This is useful for correcting database corruption.
</para>
</listitem>

<listitem>
<!--
Author: Robert Haas <rhaas@postgresql.org>
2020-09-24 [aecf5ee2b] Add new 'old_snapshot' contrib module.
-->

<para>
Add contrib module <link linkend="oldsnapshot"><application>old_snapshot</application></link> to report the <type>XID</type>/time mapping used by an active <xref linkend="guc-old-snapshot-threshold"/> (Robert Haas)
</para>
</listitem>

<listitem>
<!--
Author: Robert Haas <rhaas@postgresql.org>
2020-10-22 [866e24d47] Extend amcheck to check heap pages.
-->

<para>
Allow <link linkend="amcheck"><application>amcheck</application></link> to also check heap pages (Mark Dilger)
</para>

<para>
Previously it only checked B-Tree index pages.
</para>
</listitem>

<listitem>
<!--
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
2021-01-13 [756ab2912] Add functions to 'pageinspect' to inspect GiST indexes.
Author: Peter Geoghegan <pg@bowt.ie>
2021-02-14 [9e596b65f] Add "LP_DEAD item?" column to GiST pageinspect functions
-->

<para>
Allow <link linkend="pageinspect"><application>pageinspect</application></link> to inspect GiST indexes (Andrey Borodin, Heikki Linnakangas)
</para>
</listitem>

<listitem>
<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2021-01-19 [f18aa1b20] pageinspect: Change block number arguments to bigint
-->

<para>
Change <application>pageinspect</application> block numbers to be <link linkend="datatype-int"><type>bigints</type></link> (Peter Eisentraut)
</para>
</listitem>

<listitem>
<!--
Author: Alexander Korotkov <akorotkov@postgresql.org>
2020-07-20 [d98c08cdc] Update btree_gist extension for parallel query
-->

<para>
Mark <link linkend="btree-gist"><application>btree_gist</application></link> functions as parallel safe (Steven Winfield)
</para>
</listitem>

    </itemizedlist>

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

     <itemizedlist>

<listitem>
<!--
Author: Bruce Momjian <bruce@momjian.us>
2021-04-07 [5fd9dfa5f] Move pg_stat_statements query jumbling to core.
-->

<para>
Move query hash computation from <application>pg_stat_statements</application> to the core server (Julien Rouhaud)
</para>

<para>
The new server variable <xref linkend="guc-compute-query-id"/>'s default of <literal>auto</literal> will automatically enable query id computation when this extension is loaded.
</para>
</listitem>

<listitem>
<!--
Author: Magnus Hagander <magnus@hagander.net>
2021-04-08 [6b4d23fee] Track identical top vs nested queries independently in p
-->

<para>
Allow <application>pg_stat_statements</application> to track top and nested statements independently (Julien Rohaud)
</para>

<para>
Previously, when tracking all statements, identical top and nested statements were tracked together.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-07-29 [6023b7ea7] pg_stat_statements: track number of rows processed by so
Author: Fujii Masao <fujii@postgresql.org>
2020-11-12 [b62e6056a] pg_stat_statements: track number of rows processed by RE
-->

<para>
Add row counts for utility commands to <structname>pg_stat_statements</structname>> (Fujii Masao, Katsuragi Yuta, Seino Yuki)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-11-26 [9fbc3f318] pg_stat_statements: Track number of times pgss entries w
Author: Fujii Masao <fujii@postgresql.org>
2020-12-18 [2e0fedf03] pg_stat_statements: Track time at which all statistics w
-->

<para>
Add <structname>pg_stat_statements_info</structname> system view to show <structname>pg_stat_statements</structname> activity (Katsuragi Yuta, Yuki Seino, Naoki Nakamichi)
</para>
</listitem>

    </itemizedlist>

    </sect4>

    <sect4>
     <title><link linkend="postgres-fdw"><application>postgres_fdw</application></link></title>

     <itemizedlist>

<listitem>
<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-01-20 [b663a4136] Implement support for bulk inserts in postgres_fdw
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2021-02-18 [927f453a9] Fix tuple routing to initialize batching only for insert
-->

<para>
Allow <application>postgres_fdw</application> to <command>INSERT</command> rows in bulk (Takayuki Tsunakawa, Tomas Vondra, Amit Langote)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-04-07 [a3740c48e] postgres_fdw: Allow partitions specified in LIMIT TO to 
-->

<para>
Allow <application>postgres_fdw</application> to import table partitions if specified by <link linkend="sql-importforeignschema"><command>IMPORT FOREIGN SCHEMA ... LIMIT TO</command></link> (Matthias van de Meent)
</para>

<para>
By default, only the root of partitioned tables is imported.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-01-18 [708d165dd] postgres_fdw: Add function to list cached connections to
-->

<para>
Add <application>postgres_fdw</application> function <function>postgres_fdw_get_connections()</function> to report open foreign server connections (Bharath Rupireddy)
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-04-02 [b1be3074a] postgres_fdw: Add option to control whether to keep conn
-->

<para>
Allow control over whether foreign servers keep connections open after transaction completion (Bharath Rupireddy)
</para>

<para>
This is controlled by <varname>keep_connections</varname> and defaults to on.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2020-10-06 [32a9c0bdf] postgres_fdw: reestablish new connection if cached one i
Author: Fujii Masao <fujii@postgresql.org>
2020-10-16 [7fc1a81e4] postgres_fdw: Restructure connection retry logic.
-->

<para>
Allow <application>postgres_fdw</application> to reestablish foreign server connections if necessary (Bharath Rupireddy)
</para>

<para>
Previously foreign server restarts could cause foreign table access errors.
</para>
</listitem>

<listitem>
<!--
Author: Fujii Masao <fujii@postgresql.org>
2021-01-26 [411ae6499] postgres_fdw: Add functions to discard cached connection
-->

<para>
Add <application>postgres_fdw</application> functions to discard cached connections (Bharath Rupireddy)
</para>
</listitem>

     </itemizedlist>

    </sect4>

   </sect3>

  </sect2>

  <sect2 id="release-14-acknowledgements">
   <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></member>
   </simplelist>
  </sect2>

 </sect1>