<!-- 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 contrib/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 geometric data types and contrib modules cube, hstore, intarray, and 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 to_tsquery() and websearch_to_tsquery() 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 websearch_to_tsquery() 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 password_encryption server parameter to scram-sha-256 (Peter Eisentraut)
</para>

<para>
Previously it was md5.  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 clientcert in pg_hba.conf (Kyotaro Horiguchi)
</para>

<para>
Values 1/0/no-verify are no longer supported;  only the strings verify-ca and verify-full can be used.  Also, disallow verify-ca if cert authentication is enabled since cert requires verify-full
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 SSL compression (Daniel Gustafsson, Michael Paquier)
</para>

<para>
This was already disabled by default in previous Postgres releases, and most modern OpenSSL and TLS 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 libpq support for the version 2 wire protocol (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 EXTRACT to return the NUMERIC data type (Peter Eisentraut)
</para>

<para>
EXTRACT(date) 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 window function ranges (Tom Lane)
</para>

<para>
Previously window frame clauses like 'inf' PRECEDING AND 'inf' FOLLOWING 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 tablefunc's function normal_rand() 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 var_samp() and stddev_samp() with numeric parameters to return NULL for a single NaN value (Tom Lane)
</para>

<para>
Previously NaN 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 ! and !! (Mark Dilger)
</para>

<para>
The factorial() function is still supported.  Also remove function numeric_fac().
</para>
</listitem>

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

<para>
Disallow factorial() 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 postfix (right-unary) operators (Mark Dilger)
</para>

<para>
pg_dump and pg_upgrade 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 \D and \W shorthands to match newlines in newline-sensitive mode (Tom Lane)
</para>

<para>
Previously they did not match;  [^[:digit:]] or [^[:word:]] 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 ^ in its expansion in \1 in "(^\d+).*\1".
</para>
</listitem>

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

<para>
Disallow \w 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>
Force custom server variable names to match the pattern used for unquoted SQL identifiers (Tom Lane)
</para>
</listitem>

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

<para>
Return false for has_column_privilege() 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 ecpg SQL command strings literally (Tom Lane)
</para>

<para>
Previously 'abc''def' was passed to the server as 'abc'def', and "abc""def" was passed as "abc"def".
</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 CREATE/DROP LANGUAGE command (Peter Eisentraut)
</para>
</listitem>

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

<para>
Remove contrib program pg_standby (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 composite types 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 operator_precedence_warning setting (Tom Lane)
</para>

<para>
This was needed for warning applications about PostgreSQL 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 pg_read_all_data and pg_write_all_data (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 pg_database_owner;  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 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>
Add long-running queries to be canceled if the client disconnects (Sergey Cherkashin, Thomas Munro)
</para>

<para>
The server variable client_connection_check_interval allows supporting operating systems, e.g., Linux, 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 pg_wait_for_backend_termination() that waits for session exit (Bharath Rupireddy)
</para>

<para>
Also add a similar optional wait parameter to pg_terminate_backend().
</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 fill factor 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 (SNI) for SSL connection packets (Peter Eisentraut)
</para>

<para>
This can be disabled by turning client option "sslsni" off.
</para>
</listitem>

   </itemizedlist>

    <sect4>
     <title>Vacuuming</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 vacuum_cost_page_miss (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 TOAST tables (Nathan Bossart)
</para>

<para>
VACUUM now has a PROCESS_TOAST which can be set to false to disable TOAST processing, and vacuumdb has a --no-process-toast 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 COPY FREEZE 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 vacuum_failsafe_age and vacuum_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>
Autovacuum 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 autovacuum logging output (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 detached in a non-blocking manner (Álvaro Herrera)
</para>

<para>
The syntax is ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY, and FINALIZE.
</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 remove expired index entries 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 BRIN 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 BRIN 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 GiST 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 SP-GiST to use INCLUDE'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 IN 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 extended statistics can be used for OR 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 pg_stats_ext_exprs reports such statistics.
ALTER TABLE ... ALTER COLUMN ... TYPE RESETS STASTISTICS?
</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 tids (Edmund Horner, David Rowley)
</para>

<para>
Previously a sequential scan was required for non-equality tid 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 EXPLAIN CREATE TABLE AS and EXPLAIN CREATE MATERIALIZED VIEW to honor IF NOT EXISTS (Bharath Rupireddy)
</para>

<para>
Previously, if the object already exists, EXPLAIN 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 MVCC visibility snapshots 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 window functions 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 parallel workers.
</para>
</listitem>

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

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

<para>
The postgres_fdw supports these type of scans if "async_capable" is set.
</para>
</listitem>

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

<para>
Allow analyze to do page prefetching (Stephen Frost)
</para>

<para>
This is controlled by 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 regular expression 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 normalize() and IS NORMALIZED.
</para>
</listitem>

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

<para>
Add ability to use LZ4 compression on TOAST data (Dilip Kumar)
</para>

<para>
This can be set at the column level, or set as a default via server setting default_toast_compression.  The server must be compiled with --with-lz4 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 compute_query_id is enabled, display the query id in pg_stat_activity, EXPLAIN VERBOSE, csvlog, and optionally in 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 pg_backend_memory_contexts 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 pg_backend_memory_contexts() 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 auto-vacuum and auto-analyze (Stephen Frost, Jakub Wartak)
</para>

<para>
This reports I/O timings for auto-vacuum and auto-analyze if 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 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 pg_stat_progress_copy to report COPY 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 pg_stat_database 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 pg_prepared_statements 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 time to pg_locks (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 pg_stat_wal which reports WAL 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 pg_stat_replication_slots to report replication slot activity (Sawada Masahiko, Amit Kapila, Vignesh C)
</para>

<para>
Function pg_stat_reset_replication_slot() 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 pg_stat_activity reporting of walsender processes (Tom Lane)
</para>

<para>
Previously only SQL 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 pg_stat_activity (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 WalReceiverExit to report WAL 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 routine_column_usage 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 (DN) to be matched for client certificate authentication (Andrew Dunstan)
</para>

<para>
The new pg_hba.conf keyword "clientname=DN" allows comparison with certificate attributes beyond the CN 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 pg_hba.conf and pg_ident.conf 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 (CRL) directory (Kyotaro Horiguchi)
</para>

<para>
This is controlled by server variable ssl_crl_dir and libpq connection option sslcrldir.  Previously only CRL 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 idle_session_timeout to close idle sessions (Li Japin)
</para>

<para>
This is similar to 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 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>
Add %P to 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 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 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 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 pg_rewind (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 restore_command setting to be changed during a server reload (Sergei Kornilov)
</para>

<para>
You can also set restore_command to an empty string and reload to force recovery to only read from the pg_wal 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 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 pg_get_wal_replay_pause_state() to report the recovery state (Dilip Kumar)
</para>

<para>
It gives more detailed information than pg_is_wal_replay_paused(), 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 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, recovery_init_sync_method=syncfs, 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 pg_xact_commit_timestamp_origin() 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 pg_last_committed_xact() (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 origin functions 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>Logical Replication</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 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 API to allow streaming large in-progress transactions (Tomas Vondra, Dilip Kumar, Amit Kapila)
</para>

<para>
The output functions begin with "stream".  test_decoding 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 WAL-log subtransaction and top-level XID 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 pg_create_logical_replication_slot().
</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 WAL invalidations message during command completion when using logical replication (Dilip Kumar, Tomas Vondra, Amit Kapila)
</para>

<para>
When logical replication is disabled, WAL 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 Logical decoding to work efficiently in presence of a large amount of DDL.
</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>SELECT, INSERT</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 "AS" (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 JOIN ... USING
-->

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

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

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

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

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

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

<para>
Properly handle DEFAULT 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 SQL-standard SEARCH and CYCLE clauses for common table expressions (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 WHERE clause of ON CONFLICT 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 REFRESH MATERIALIZED VIEW 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 REINDEX to change the tablespace of the new index (Alexey Kondratov, Michael Paquier, Justin Pryzby)
</para>

<para>
This is done by specifying a TABLESPACE 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 REINDEX 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 COPY FROM 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 SQL standard syntax in view definitions, if possible (Tom Lane)
</para>

<para>
Previously non-function call SQL standard syntax, e.g. EXTRACT, were converted to non-SQL 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 SQL-standard clause GRANTED BY to GRANT and REVOKE (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 OR REPLACE for CREATE TRIGGER (Takamichi Osumi)
</para>

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

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

<para>
Allow TRUNCATE to operate on foreign tables (Kazutaka Onishi, Kohei KaiGai)
</para>

<para>
The postgres_fdw 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 ALTER SUBSCRIPTION ... ADD/DROP PUBLICATION.  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 system catalogs (Peter Eisentraut)
</para>

<para>
This helps GUI 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 CURRENT_ROLE every place CURRENT_USER 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 subscripting (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 JSONB (Dmitry Dolgov)
</para>

<para>
JSONB subscripting can be used to extract and assign to portions of JSONB 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 multirange data types (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 point operators &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 stemming 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 tsearch data files to have unlimited line lengths (Tom Lane)
</para>

<para>
The previous limit was 4k bytes.  Also remove function t_readline().
</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 -infinity values to the numeric data type (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 float values 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 LSN 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 binary data transfer to be more forgiving of array and record OID 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 SQL-language functions and procedures to use SQL-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 procedures to have OUT 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 array_append() array_prepend(), array_cat(), array_position(), array_positions(), array_remove(), array_replace(), and width_bucket().  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 SQL-standard trim_array() 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 ltrim() and rtrim() (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 split_part() (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>
A string_to_table() function to split a string on delimiters (Pavel Stehule)
</para>

<para>
This is similar to the regexp_split_to_table() function.
</para>
</listitem>

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

<para>
Add unistr() 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 bit_xor 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 bit_count() 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 date_bin function (John Naylor)
</para>

<para>
The function date_bin "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 make_timestamp/make_timestamptz to accept negative years (Peter Eisentraut)
</para>

<para>
They are interpreted as BC 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 substring() syntax (Peter Eisentraut)
</para>

<para>
The new syntax is SUBSTRING(text SIMILAR pattern ESCAPE escapechar).  The previous standard syntax was SUBSTRING(text FROM pattern FOR escapechar), 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 \D, \S, and \W 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 [[:word:]] 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 lead() and lag() 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 exp() and power() 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 pg_stat_get_subscription() 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.
</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 inet_server_addr() and inet_server_port() 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 pg_describe_object(), pg_identify_object(), and pg_identify_object_as_address() 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 expression and assignment 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 RETURN QUERY 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 CALLs 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 pipeline 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 target_session_attrs parameter options (Haribabu Kommi, Greg Nancarrow, Vignesh C, Tom Lane)
</para>

<para>
New options are "read-only", "primary", "standby", and "prefer-standby".
</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 PQtrace() (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 libpq service files 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 ECPG SQL identifier to be linked to a specific connection (Hayato Kuroda)
</para>

<para>
This is done via DECLARE ... STATEMENT.
</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 reindexdb to change the tablespace of the new index (Michael Paquier)
</para>

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

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

<para>
Allow vacuumdb to skip index cleanup and truncation (Nathan Bossart)
</para>

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

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

<para>
Allow pg_dump to dump only certain extensions (Guillaume Lelarge)
</para>

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

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

<para>
Add pgbench permute() 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 (-v) to increase the logging verbosity (Tom Lane)
</para>

<para>
This is now supported by pg_dump, pg_dumpall, and pg_restore.
</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 psql'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 psql'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 psql's \dt and \di to show TOAST 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 psql 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 psql'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 psql'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 psql's handling of \connect with -reuse-previous (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 pg_amcheck 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 --no-instructions option to initdb (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 pg_upgrade from creating analyze_new_cluster script (Michael Paquier)
</para>

<para>
Instead, give comparable vacuumdb instructions.
</para>
</listitem>

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

<para>
Remove support for the postmaster -o 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 Predefined Roles (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 factorial() function (Peter Eisentraut)
</para>

<para>
With the removal of the ! operator in this release, factorial() 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 --with-ssl={openssl} to behave like --with-openssl (Daniel Gustafsson, Michael Paquier)
</para>

<para>
The option --with-openssl 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 abstract Unix-domain sockets (Peter Eisentraut)
</para>

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

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

<para>
Add 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 valgrind 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 LLVM 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 OpenSSL EVP API (Michael Paquier)
</para>

<para>
This is more modern and supports FIPS 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 FreeBSD (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 "amadjustmembers" to the index access method API (Tom Lane)
</para>

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

    </itemizedlist>

   </sect3>

   <sect3>
    <title>Additional Modules</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 pg_stat_statements to the core server (Julien Rouhaud)
</para>

<para>
The new server variable compute_query_id's default of 'auto' 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 pg_stat_statements 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 pg_stat_statements (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 pg_stat_statements_info system view to show pg_stat_statements activity (Katsuragi Yuta, Yuki Seino, Naoki Nakamichi)
</para>
</listitem>

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

<para>
Allow subscripting of hstore 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 pg_trgm indexes to do equality lookups (Julien Rouhaud)
</para>

<para>
This is similar to LIKE 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 cube data type to be transferred in binary mode (KaiGai Kohei)
</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 pg_surgery 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 old_snapshot to report the XID/time mapping used by an active 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 amcheck 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 pageinspect 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 pageinspect block numbers to be bigints (Peter Eisentraut)
</para>
</listitem>

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

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

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

<para>
Mark btree_gist functions as parallel safe (Steven Winfield)
</para>
</listitem>

    </itemizedlist>

    <sect4>
     <title>postgres_fdw</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 postgres_fdw to INSERT 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 postgres_fdw to import table partitions if specified by IMPORT FOREIGN SCHEMA ... LIMIT TO (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 postgres_fdw function postgres_fdw_get_connections to report open foreign server connections (Bharath Rupireddy)
</para>
</listitem>

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

<para>
Add postgres_fdw functions to discard cached connections (Bharath Rupireddy)
</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 postgres_fdw to reestablish foreign server connections if necessary (Bharath Rupireddy)
</para>

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