postgres/doc/src/sgml/release-16.sgml

<!-- doc/src/sgml/release-16.sgml -->
<!-- See header comment in release.sgml about typical markup -->

 <sect1 id="release-16">
  <title>Release 16</title>

  <formalpara>
   <title>Release date:</title>
   <para>AS OF 2023-08-14, 2023-??-??</para>
  </formalpara>

  <sect2 id="release-16-highlights">
   <title>Overview</title>

   <para>
    <productname>PostgreSQL</productname> 16 contains many new features
    and enhancements, including:
   </para>

   <itemizedlist>

    <listitem>
     <para>
      Allow parallelization of <literal>FULL</literal> and internal right <literal>OUTER</literal> hash joins
     </para>
    </listitem>

    <listitem>
     <para>
      Allow logical replication from standby servers
     </para>
    </listitem>

    <listitem>
     <para>
      Allow logical replication subscribers to apply large transactions in parallel
     </para>
    </listitem>

    <listitem>
     <para>
      Allow monitoring of <acronym>I/O</acronym> statistics using the new <structname>pg_stat_io</structname> view
     </para>
    </listitem>

    <listitem>
     <para>
      Add <acronym>SQL/JSON</acronym> constructors and identity functions
     </para>
    </listitem>

    <listitem>
     <para>
      Improve performance of vacuum freezing
     </para>
    </listitem>

    <listitem>
     <para>
      Add support for regular expression matching of user and database names in <filename>pg_hba.conf</filename>, and user names in <filename>pg_ident.conf</filename>
     </para>
    </listitem>

   </itemizedlist>

   <para>
    The above items and other new features of
    <productname>PostgreSQL</productname> 16 are explained in more detail
    in the sections below.
   </para>

  </sect2>

  <sect2  id="release-16-migration">

   <title>Migration to Version 16</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 16 contains a number of changes that may affect compatibility
     with previous releases.  Observe the following incompatibilities:
    </para>

   <itemizedlist>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-01 [d747dc85a] In plpgsql, don't preassign portal names to bound cursor
-->

<listitem>
<para>
Change assignment rules for <link linkend="plpgsql-open-bound-cursor"><application>PL/pgSQL</application></link> bound cursor variables (Tom Lane)
</para>

<para>
Previously, the string value of such variables was set to match the variable name during cursor assignment;  now it will be assigned during <link linkend="plpgsql-cursor-opening"><command>OPEN</command></link>, and will not match the variable name.
To restore the previous behavior, assign the desired portal name to the cursor variable before <command>OPEN</command>.
</para>
</listitem>

<!--
Author: Daniel Gustafsson <dgustafsson@postgresql.org>
2023-02-24 [d95952325] Disallow NULLS NOT DISTINCT indexes for primary keys
-->

<listitem>
<para>
Disallow <link linkend="sql-createindex"><literal>NULLS NOT DISTINCT</literal></link> indexes for primary keys (Daniel Gustafsson)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-07-19 [2cbc3c17a] Rework logic and simplify syntax of REINDEX DATABASE/SYS
Author: Michael Paquier <michael@paquier.xyz>
2022-07-26 [0a5f06b84] Fix a few issues with REINDEX grammar
-->

<listitem>
<para>
Change <link linkend="sql-reindex"><command>REINDEX DATABASE</command></link> and <link linkend="app-reindexdb"><application>reindexdb</application></link> to not process indexes on system catalogs (Simon Riggs)
</para>

<para>
Processing such indexes is still possible using <command>REINDEX SYSTEM</command> and <link linkend="app-reindexdb"><command>reindexdb --system</command></link>.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-11 [8bf6ec3ba] Improve handling of inherited GENERATED expressions.
-->

<listitem>
<para>
Tighten <link linkend="ddl-generated-columns"><literal>GENERATED</literal></link> expression restrictions on inherited and partitioned tables (Amit Langote, Tom Lane)
</para>

<para>
Columns of parent/partitioned and child/partition tables must all have the same generation status, though now the actual generation expressions can be different.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-03-14 [5c1b66280] Rework design of functions in pg_walinspect
-->

<listitem>
<para>
Remove <link linkend="pgwalinspect"><application>pg_walinspect</application></link> functions <function>pg_get_wal_records_info_till_end_of_wal()</function> and <function>pg_get_wal_stats_till_end_of_wal()</function> (Bharath Rupireddy)
</para>
</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2023-02-15 [5352ca22e] Rename force_parallel_mode to debug_parallel_query
Author: David Rowley <drowley@postgresql.org>
2023-04-14 [0981846b9] Remove old GUC name mapping for "force_parallel_mode"
-->

<listitem>
<para>
Rename server variable <varname>force_parallel_mode</varname> to <link linkend="guc-debug-parallel-query"><varname>debug_parallel_query</varname></link> (David Rowley)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-12-02 [b23cd185f] Remove logic for converting a table to a view.
-->

<listitem>
<para>
Remove the ability to <link linkend="sql-createview">create views</link> manually with <literal>ON SELECT</literal> rules (Tom Lane)
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2023-04-24 [1118cd37e] Remove vacuum_defer_cleanup_age
-->

<listitem>
<para>
Remove the server variable <varname>vacuum_defer_cleanup_age</varname> (Andres Freund)
</para>

<para>
This has been unnecessary since <link linkend="guc-hot-standby-feedback"><varname>hot_standby_feedback</varname></link> and <link linkend="streaming-replication-slots">replication slots</link> were added.
</para>
</listitem>

<!--
Author: Thomas Munro <tmunro@postgresql.org>
2022-11-29 [cd4329d93] Remove promote_trigger_file.
-->

<listitem>
<para>
Remove server variable <varname>promote_trigger_file</varname> (Simon Riggs)
</para>

<para>
This was used to promote a standby to primary, but is now easier accomplished with <link linkend="app-pg-ctl"><literal>pg_ctl promote</literal></link> or <link linkend="functions-recovery-control-table"><function>pg_promote()</function></link>.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-06-07 [b0f6c4371] Remove read-only server settings lc_collate and lc_ctype
-->

<listitem>
<para>
Remove read-only server variables <varname>lc_collate</varname> and <varname>lc_ctype</varname> (Peter Eisentraut)
</para>

<para>
Collations and locales can vary between databases so having them as read-only server variables was unhelpful.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-08-25 [e3ce2de09] Allow grant-level control of role inheritance behavior.
-->

<listitem>
<para>
Role inheritance now controls the default inheritance status of member roles added during <link linkend="sql-grant"><command>GRANT</command></link> (Robert Haas)
</para>

<para>
The role's default inheritance behavior can be overridden with the new <command>GRANT ... WITH INHERIT</command> clause.
This allows inheritance of some roles and not others because the members' inheritance status is set at <command>GRANT</command> time.
Previously the inheritance status of member roles was controlled only by the role's inheritance status, and
changes to a role's inheritance status affected all previous and future member roles.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2023-01-10 [cf5eb37c5] Restrict the privileges of CREATEROLE users.
Author: Robert Haas <rhaas@postgresql.org>
2023-01-24 [f1358ca52] Adjust interaction of CREATEROLE with role properties.
-->

<listitem>
<para>
Restrict the privileges of <link linkend="sql-createrole"><literal>CREATEROLE</literal></link> and its ability to modify other roles (Robert Haas)
</para>

<para>
Previously roles with <literal>CREATEROLE</literal> privileges could change many aspects of any non-superuser role.  Such changes, including adding members, now require the role requesting the change to have <literal>ADMIN OPTION</literal>
permission.  For example, they can now change the <literal>CREATEDB</literal>, <literal>REPLICATION</literal>, and <literal>BYPASSRLS</literal> properties only if they also have those permissions.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-01-26 [37e267335] Don't install postmaster symlink anymore
-->

<listitem>
<para>
Remove symbolic links for the <application>postmaster</application> binary (Peter Eisentraut)
</para>
</listitem>

   </itemizedlist>

  </sect2>

  <sect2 id="release-16-changes">
   <title>Changes</title>

   <para>
    Below you will find a detailed account of the changes between
    <productname>PostgreSQL</productname> 16 and the previous major
    release.
   </para>

   <sect3 id="release-16-server">
    <title>Server</title>

    <sect4 id="release-16-optimizer">
     <title>Optimizer</title>

     <itemizedlist>

<!--
Author: David Rowley <drowley@postgresql.org>
2022-08-02 [b59242209] Relax overly strict rules in select_outer_pathkeys_for_m
Author: David Rowley <drowley@postgresql.org>
2023-01-11 [3c6fc5820] Have the planner consider Incremental Sort for DISTINCT
-->

<listitem>
<para>
Allow incremental sorts in more cases, including <literal>DISTINCT</literal> (David Rowley)
</para>
</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2022-08-02 [1349d2790] Improve performance of ORDER BY / DISTINCT aggregates
Author: David Rowley <drowley@postgresql.org>
2022-12-20 [3226f4728] Add enable_presorted_aggregate GUC
Author: David Rowley <drowley@postgresql.org>
2023-01-17 [da5800d5f] Don't presort ORDER BY/DISTINCT Aggrefs with volatile fu
-->

<listitem>
<para>
Add the ability for aggregates having <literal>ORDER BY</literal> or <literal>DISTINCT</literal> to use pre-sorted data (David Rowley)
</para>

<para>
The new server variable <link linkend="guc-enable-presorted-aggregate"><varname>enable_presorted_aggregate</varname></link> can be used to disable this.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-16 [9bfd2822b] Enable use of Memoize atop an Append that came from UNIO
-->

<listitem>
<para>
Allow memoize atop a <literal>UNION ALL</literal> (Richard Guo)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-04-05 [16dc2703c] Support "Right Anti Join" plan shapes.
-->

<listitem>
<para>
Allow anti-joins to be performed with the non-nullable input as the inner relation (Richard Guo)
</para>
</listitem>

<!--
Author: Thomas Munro <tmunro@postgresql.org>
2023-03-31 [11c2d6fdf] Parallel Hash Full Join.
-->

<listitem>
<para>
Allow parallelization of <link linkend="queries-join"><literal>FULL</literal></link> and internal right <literal>OUTER</literal> hash joins (Melanie Plageman, Thomas Munro)
</para>
</listitem>

<!--
Author: Alexander Korotkov <akorotkov@postgresql.org>
2023-01-08 [cd9479af2] Improve GIN cost estimation
-->

<listitem>
<para>
Improve the accuracy of <link linkend="gin"><literal>GIN</literal></link> index access optimizer costs (Ronan Dunklau)
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4 id="release-16-performance">
     <title>General Performance</title>

     <itemizedlist>

<!--
Author: Andres Freund <andres@anarazel.de>
2023-04-06 [00d1e02be] hio: Use ExtendBufferedRelBy() to extend tables more eff
Author: Andres Freund <andres@anarazel.de>
2023-04-06 [26158b852] Use ExtendBufferedRelTo() in XLogReadBufferExtended()
-->

<listitem>
<para>
Allow more efficient addition of heap and index pages (Andres Freund)
</para>
</listitem>

<!--
Author: Peter Geoghegan <pg@bowt.ie>
2022-09-08 [d977ffd92] Instrument freezing in autovacuum log reports.
Author: Peter Geoghegan <pg@bowt.ie>
2022-11-15 [9e5405993] Deduplicate freeze plans in freeze WAL records.
Author: Peter Geoghegan <pg@bowt.ie>
2022-12-28 [1de58df4f] Add page-level freezing to VACUUM.
-->

<listitem>
<para>
During non-freeze operations, perform page <link linkend="vacuum-for-wraparound">freezing</link> where appropriate (Peter Geoghegan)
</para>

<para>
This makes full-table freeze vacuums less necessary.
</para>
</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2022-12-23 [ed1a88dda] Allow window functions to adjust their frameOptions
-->

<listitem>
<para>
Allow window functions to use <link linkend="syntax-window-functions"><literal>ROWS</literal></link> mode internally when <literal>RANGE</literal> mode is specified but unnecessary (David Rowley)
</para>
</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2023-01-27 [456fa635a] Teach planner about more monotonic window functions
-->

<listitem>
<para>
Allow optimization of always-increasing window functions <link linkend="functions-window-table"><function>ntile()</function></link>, <function>cume_dist()</function> and <function>percent_rank()</function> (David Rowley)
</para>
</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2023-01-23 [16fd03e95] Allow parallel aggregate on string_agg and array_agg
-->

<listitem>
<para>
Allow aggregate functions <link linkend="functions-aggregate-table"><function>string_agg()</function></link> and <function>array_agg()</function> to be parallelized (David Rowley)
</para>
</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2022-08-02 [3592e0ff9] Have ExecFindPartition cache the last found partition
-->

<listitem>
<para>
Improve performance by caching <link linkend="ddl-partitioning-overview"><literal>RANGE</literal></link> and <literal>LIST</literal> partition lookups (Amit Langote, Hou Zhijie, David Rowley)
</para>
</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2023-04-07 [1cbbee033] Add VACUUM/ANALYZE BUFFER_USAGE_LIMIT option
Author: David Rowley <drowley@postgresql.org>
2023-04-07 [ae78cae3b] Add - -buffer-usage-limit option to vacuumdb
Author: Masahiko Sawada <msawada@postgresql.org>
2023-04-28 [b72f564d8] Add unit to vacuum_buffer_usage_limit value in postgresq
-->

<listitem>
<para>
Allow control of the shared buffer usage by vacuum and analyze (Melanie Plageman)
</para>

<para>
The <link linkend="sql-vacuum"><command>VACUUM</command></link>/<link linkend="sql-analyze"><command>ANALYZE</command></link> option is <literal>BUFFER_USAGE_LIMIT</literal>, and the <link linkend="app-vacuumdb"><application>vacuumdb</application></link> option is <option>--buffer-usage-limit</option>.  The default value is set by server variable <link linkend="guc-vacuum-buffer-usage-limit"><varname>vacuum_buffer_usage_limit</varname></link>, which also controls autovacuum.
</para>
</listitem>

<!--
Author: Thomas Munro <tmunro@postgresql.org>
2022-07-20 [9430fb407] Add wal_sync_method=fdatasync for Windows.
-->

<listitem>
<para>
Support <link linkend="guc-wal-sync-method"><literal>wal_sync_method=fdatasync</literal></link> on <systemitem class="osname">Windows</systemitem> (Thomas Munro)
</para>
</listitem>

<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2023-03-20 [19d8e2308] Ignore BRIN indexes when checking for HOT updates
-->

<listitem>
<para>
Allow <link linkend="storage-hot"><acronym>HOT</acronym></link> updates if only <literal>BRIN</literal>-indexed columns are updated (Matthias van de Meent, Josef Simanek, Tomas Vondra)
</para>
</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2023-02-20 [2cb82e2ac] Speedup and increase usability of set proc title functio
-->

<listitem>
<para>
Improve the speed of updating the <link linkend="guc-update-process-title">process title</link> (David Rowley)
</para>
</listitem>

<!--
Author: John Naylor <john.naylor@postgresql.org>
2022-08-11 [37a6e5df3] Optimize xid/subxid searches in XidInMVCCSnapshot().
Author: John Naylor <john.naylor@postgresql.org>
2022-08-26 [121d2d3d7] Use SSE2 in is_valid_ascii() where available.
Author: John Naylor <john.naylor@postgresql.org>
2022-08-10 [b6ef16756] Introduce optimized routine for linear searches of array
Author: John Naylor <john.naylor@postgresql.org>
2022-08-26 [e813e0e16] Add optimized functions for linear search within byte ar
-->

<listitem>
<para>
Allow <type>xid</type>/<type>subxid</type> searches and <acronym>ASCII</acronym> string detection to use vector operations (Nathan Bossart, John Naylor)
</para>

<para>
<acronym>ASCII</acronym> detection is particularly useful for <link linkend="sql-copy"><command>COPY FROM</command></link>.  Vector operations are also used for some C array searches.
</para>

</listitem>

<!--
Author: David Rowley <drowley@postgresql.org>
2022-08-29 [c6e0fe1f2] Improve performance of and reduce overheads of memory ma
-->

<listitem>
<para>
Reduce overhead of memory allocations (Andres Freund, David Rowley)
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4 id="release-16-monitoring">
     <title>Monitoring</title>

     <itemizedlist>

<!--
Author: Andres Freund <andres@anarazel.de>
2023-02-11 [a9c70b46d] Add pg_stat_io view, providing more detailed IO statisti
Author: Andres Freund <andres@anarazel.de>
2023-03-30 [8aaa04b32] Track shared buffer hits in pg_stat_io
Author: Andres Freund <andres@anarazel.de>
2023-04-07 [ac8d53dae] Track IO times in pg_stat_io
Author: Michael Paquier <michael@paquier.xyz>
2023-04-21 [0ecb87e1f] Remove io prefix from pg_stat_io columns
Author: Andres Freund <andres@anarazel.de>
2023-05-17 [093e5c57d] Add writeback to pg_stat_io
-->

<listitem>
<para>
Add system view <link linkend="monitoring-pg-stat-io-view"><structname>pg_stat_io</structname></link> view to track <acronym>I/O</acronym> statistics (Melanie Plageman)
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2022-10-14 [c03747183] pgstat: Track time of the last scan of a relation
-->

<listitem>
<para>
Record statistics on the last sequential and index scans on tables (Dave Page)
</para>

<para>
This information appears in <link linkend="pg-stat-all-tables-view"><structname>pg_stat_all_tables</structname></link> and <link linkend="monitoring-pg-stat-all-indexes-view"><structname>pg_stat_all_indexes</structname></link>.
</para>
</listitem>

<!--
Author: Peter Geoghegan <pg@bowt.ie>
2023-03-23 [ae4fdde13] Count updates that move row to a new page.
-->

<listitem>
<para>
Record statistics on the occurrence of updated rows moving to new pages (Corey Huinker)
</para>

<para>
The <literal>pg_stat_*_tables</literal> column is <link linkend="monitoring-pg-stat-all-tables-view"><structfield>n_tup_newpage_upd</structfield></link>.
</para>
</listitem>

<!--
Author: Amit Kapila <akapila@postgresql.org>
2023-01-10 [f74573969] Fix the display of lock information for specktoken.
-->

<listitem>
<para>
Add speculative lock information to the <link linkend="view-pg-locks"><structname>pg_locks</structname></link> system view (Masahiko Sawada, Noriyoshi Shinoda)
</para>

<para>
The transaction id is displayed in the <structfield>transactionid</structfield> column and the speculative insertion token is displayed in the <structfield>objid</structfield> column.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2022-07-05 [84ad713cf] Add result_types column to pg_prepared_statements view
Author: Peter Eisentraut <peter@eisentraut.org>
2022-07-05 [6ffff0fd2] Fix pg_prepared_statements.result_types for DML statemen
-->

<listitem>
<para>
Add the display of prepared statement result types to the <link linkend="view-pg-prepared-statements"><structname>pg_prepared_statements</structname></link> view (Dagfinn Ilmari Mannsåker)
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2022-10-06 [e0b014295] Create subscription stats entry at CREATE SUBSCRIPTION t
-->

<listitem>
<para>
Create subscription statistics entries at subscription creation time so <link linkend="pg-stat-database-view"><structfield>stats_reset</structfield></link> is accurate (Andres Freund)
</para>

<para>
Previously entries were created only when the first statistics were reported.
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2023-04-07 [704261ecc] Improve IO accounting for temp relation writes
-->

<listitem>
<para>
Correct the <acronym>I/O</acronym> accounting for temp relation writes shown in <link linkend="pg-stat-database-view"><structname>pg_stat_database</structname></link> (Melanie Plageman)
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-12-19 [10ea0f924] Expose some information about backend subxact status.
-->

<listitem>
<para>
Add function <link linkend="monitoring-stats-backend-funcs-table"><function>pg_stat_get_backend_subxact()</function></link> to report on a session's subtransaction cache (Dilip Kumar)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-09-29 [d7e39d72c] Use actual backend IDs in pg_stat_get_backend_idset() an
-->

<listitem>
<para>
Have <link linkend="monitoring-stats-backend-funcs-table"><function>pg_stat_get_backend_idset()</function></link>, <function>pg_stat_get_backend_activity()</function>, and related functions use the unchanging backend id (Nathan Bossart)
</para>

<para>
Previously the index values might change during the lifetime of the session.
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2022-08-22 [0c679464a] Add BackendType for standalone backends
-->

<listitem>
<para>
Report stand-alone backends with a special backend type (Melanie Plageman)
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2022-11-21 [92daeca45] Add wait event for pg_usleep() in perform_spin_delay()
-->

<listitem>
<para>
Add wait event <link linkend="wait-event-timeout-table"><literal>SpinDelay</literal></link> to report spinlock sleep delays (Andres Freund)
</para>
</listitem>

<!--
Author: Thomas Munro <tmunro@postgresql.org>
2022-07-14 [7bae3bbf6] Create a distinct wait event for POSIX DSM allocation.
-->

<listitem>
<para>
Create new wait event <link linkend="wait-event-io-table"><literal>DSMAllocate</literal></link> to indicate waiting for dynamic shared memory allocation (Thomas Munro)
</para>

<para>
Previously this type of wait was reported as <literal>DSMFillZeroWrite</literal>, which was also used by <function>mmap()</function> allocations.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-11-24 [af205152e] Add the database name to the ps display of logical WAL s
-->

<listitem>
<para>
Add the database name to the <link linkend="guc-update-process-title">process title</link> of logical <acronym>WAL</acronym> senders (Tatsuhiro Nakamori)
</para>

<para>
Physical <acronym>WAL</acronym> senders do not display a database name.
</para>
</listitem>

<!--
Author: Fujii Masao <fujii@postgresql.org>
2022-07-07 [62c46eee2] Add checkpoint and REDO LSN to log_checkpoints message.
-->

<listitem>
<para>
Add checkpoint and <literal>REDO LSN</literal> information to <link linkend="guc-log-checkpoints"><varname>log_checkpoints</varname></link> messages (Bharath Rupireddy, Kyotaro Horiguchi)
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2022-07-15 [3a0e38504] Log details for client certificate failures
-->

<listitem>
<para>
Provide additional details during client certificate failures (Jacob Champion)
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4 id="release-16-privileges">
     <title>Privileges</title>

     <itemizedlist>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2023-03-30 [c3afe8cf5] Add new predefined role pg_create_subscription.
-->

<listitem>
<para>
Add predefined role <link linkend="predefined-roles"><literal>pg_create_subscription</literal></link> with permission to create subscriptions (Robert Haas)
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2023-03-30 [c3afe8cf5] Add new predefined role pg_create_subscription.
Author: Amit Kapila <akapila@postgresql.org>
2023-04-20 [c1cc4e688] Restart the apply worker if the 'password_required' opti
Author: Amit Kapila <akapila@postgresql.org>
2023-04-24 [19e65dff3] Display 'password_required' option for \dRs+ command.
-->

<listitem>
<para>
Allow subscriptions to not require passwords (Robert Haas)
</para>

<para>
This is accomplished with the option <link linkend="sql-createsubscription"><literal>password_required=false</literal></link>.
</para>
</listitem>

<!--
Author: Jeff Davis <jdavis@postgresql.org>
2023-01-13 [c44f6334c] Simplify permissions for LOCK TABLE.
-->

<listitem>
<para>
Simplify permissions for <link linkend="sql-lock"><command>LOCK TABLE</command></link> (Jeff Davis)
</para>

<para>
Previously the ability to perform <command>LOCK TABLE</command> at various lock levels was bound to specific query-type permissions.  For example, <link linkend="sql-update"><command>UPDATE</command></link> could perform all lock levels except <literal>ACCESS SHARE</literal>, which
required <link linkend="sql-select"><command>SELECT</command></link> permissions.  Now <command>UPDATE</command> can issue all lock levels.  MORE?
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-08-22 [ce6b672e4] Make role grant system more consistent with other privil
-->

<listitem>
<para>
Allow <link linkend="sql-grant"><literal>GRANT group_name TO user_name</literal></link> to be performed with <literal>ADMIN OPTION</literal> (Robert Haas)
</para>

<para>
Previously <literal>CREATEROLE</literal> permission was required.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-08-25 [e3ce2de09] Allow grant-level control of role inheritance behavior.
-->

<listitem>
<para>
Allow <link linkend="sql-grant"><command>GRANT</command></link> to use <literal>WITH ADMIN TRUE</literal>/<literal>FALSE</literal> syntax (Robert Haas)
</para>

<para>
Previously only the <literal>WITH ADMIN OPTION</literal> syntax was supported.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2023-01-10 [e5b8a4c09] Add new GUC createrole_self_grant.
Author: Daniel Gustafsson <dgustafsson@postgresql.org>
2023-02-22 [e00bc6c92] doc: Add default value of createrole_self_grant
-->

<listitem>
<para>
Allow roles that create other roles to automatically inherit the new role's rights or the ability to <link linkend="sql-set-role"><command>SET ROLE</command></link> to the new role (Robert Haas, Shi Yu)
</para>

<para>
This is controlled by server variable <link linkend="guc-createrole-self-grant"><varname>createrole_self_grant</varname></link>.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-09-19 [48a257d44] Make ALTER DEFAULT PRIVILEGES require privileges, not me
-->

<listitem>
<para>
Prevent users from changing the default privileges of non-inherited roles (Robert Haas)
</para>

<para>
This is now only allowed for inherited roles.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-08-22 [ce6b672e4] Make role grant system more consistent with other privil
-->

<listitem>
<para>
When granting role membership, require the granted-by role to be a role that has appropriate permissions (Robert Haas)
</para>

<para>
This is a requirement even when a non-bootstrap superuser is granting role membership.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-08-22 [ce6b672e4] Make role grant system more consistent with other privil
-->

<listitem>
<para>
Allow non-superusers to grant permissions using a granted-by user that is not the current user (Robert Haas)
</para>

<para>
The current user still must have sufficient permissions given by the specified granted-by user.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-11-18 [3d14e171e] Add a SET option to the GRANT command.
-->

<listitem>
<para>
Add <link linkend="sql-grant"><command>GRANT</command></link> to control permission to use <link linkend="sql-set-role"><command>SET ROLE</command></link> (Robert Haas)
</para>

<para>
This is controlled by a new <literal>GRANT ... SET</literal> option.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-08-22 [ce6b672e4] Make role grant system more consistent with other privil
-->

<listitem>
<para>
Add dependency tracking to roles which have granted privileges (Robert Haas)
</para>

<para>
For example, removing <literal>ADMIN OPTION</literal> will fail if there are privileges using that option;  <literal>CASCADE</literal> must be used to revoke dependent permissions.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-08-18 [6566133c5] Ensure that pg_auth_members.grantor is always valid.
-->

<listitem>
<para>
Add dependency tracking of grantors for <link linkend="sql-grant"><command>GRANT</command></link> records (Robert Haas)
</para>

<para>
This guarantees that <link linkend="catalog-pg-auth-members"><structname>pg_auth_members</structname></link>.<structfield>grantor</structfield> values are always valid.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-08-22 [ce6b672e4] Make role grant system more consistent with other privil
Author: Robert Haas <rhaas@postgresql.org>
2022-08-31 [0101f770a] Fix a bug in roles_is_member_of.
-->

<listitem>
<para>
Allow multiple role membership records (Robert Haas)
</para>

<para>
Previously a new membership grant would remove a previous matching membership grant, even if other aspects of the grant did not match.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2022-07-26 [e530be2c5] Do not allow removal of superuser privileges from bootst
-->

<listitem>
<para>
Prevent removal of superuser privileges for the bootstrap user (Robert Haas)
</para>

<para>
Restoring such users could lead to errors.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-07-03 [b762bbde3] Allow makeaclitem() to accept multiple privilege names.
-->

<listitem>
<para>
Allow <link linkend="functions-aclitem-fn-table"><function>makeaclitem()</function></link> to accept multiple privilege names (Robins Tharakan)
</para>

<para>
Previously only a single privilege name, like <link linkend="sql-select"><command>SELECT</command></link>, was accepted.
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4 id="release-16-server-config">
     <title>Server Configuration</title>

     <itemizedlist>

<!--
Author: Stephen Frost <sfrost@snowman.net>
2023-04-13 [6633cfb21] De-Revert "Add support for Kerberos credential delegatio
Author: Bruce Momjian <bruce@momjian.us>
2023-05-20 [9c0a0e2ed] rename "gss_accept_deleg" to "gss_accept_delegation".
Author: Nathan Bossart <nathan@postgresql.org>
2023-05-20 [f4001a553] Fix remaining references to gss_accept_deleg.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-05-21 [a2eb99a01] Expand some more uses of "deleg" to "delegation" or "del
-->

<listitem>
<para>
Add support for <productname>Kerberos</productname> credential delegation (Stephen Frost)
</para>

<para>
This is enabled with server variable <link linkend="guc-gss-accept-delegation"><varname>gss_accept_delegation</varname></link> and <application>libpq</application> connection parameter <link linkend="libpq-connect-gssdelegation"><literal>gssdelegation</literal></link>.
</para>
</listitem>

<!--
Author: Daniel Gustafsson <dgustafsson@postgresql.org>
2023-03-27 [b57774300] Make SCRAM iteration count configurable
-->

<listitem>
<para>
Allow the <acronym>SCRAM</acronym> iteration count to be set with server variable <link linkend="guc-scram-iterations"><varname>scram_iterations</varname></link> (Daniel Gustafsson)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-10-14 [3057465ac] Replace the sorted array of GUC variables with a hash ta
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-10-14 [f13b2088f] Add auxiliary lists to GUC data structures for better pe
-->

<listitem>
<para>
Improve performance of server variable management (Tom Lane)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-09-27 [385366426] Introduce GUC_NO_RESET flag.
-->

<listitem>
<para>
Tighten restrictions on which server variables can be reset (Masahiko Sawada)
</para>

<para>
Previously, while certain variables, like <link linkend="guc-default-transaction-isolation"><varname>transaction_isolation</varname></link>, were not affected by <link linkend="sql-reset"><command>RESET ALL</command></link>, they could be individually reset in inappropriate situations.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-08-09 [0b039e3a8] Fix some inconsistencies with GUC categories
-->

<listitem>
<para>
Move various <link linkend="config-setting-configuration-file"><filename>postgresql.conf</filename></link> items into new categories (Shinya Kato)
</para>

<para>
This also affects the categories displayed in the <link linkend="view-pg-settings"><structname>pg_settings</structname></link> view.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-11-25 [d13b68411] Introduce variables for initial and max nesting depth on
-->

<listitem>
<para>
Prevent configuration file recursion beyond 10 levels (Julien Rouhaud)
</para>
</listitem>

<!--
Author: Daniel Gustafsson <dgustafsson@postgresql.org>
2023-04-07 [7d71d3dd0] Refresh cost-based delay params more frequently in autov
Author: Daniel Gustafsson <dgustafsson@postgresql.org>
2023-04-20 [a9781ae11] Fix autovacuum cost debug logging
-->

<listitem>
<para>
Allow <link linkend="autovacuum">autovacuum</link> to more frequently honor changes to delay settings (Melanie Plageman)
</para>

<para>
Rather than honor changes only at the start of each relation, honor them at the start of each block.
</para>
</listitem>

<!--
Author: Fujii Masao <fujii@postgresql.org>
2022-07-26 [756e221db] Reduce overhead of renaming archive status files.
Author: Fujii Masao <fujii@postgresql.org>
2022-07-26 [3cabe45a8] doc: Add note about re-archiving of same WAL files in do
-->

<listitem>
<para>
Remove restrictions that archive files be durably renamed (Nathan Bossart)
</para>

<para>
The <link linkend="guc-archive-command"><varname>archive_command</varname></link> command is now more likely to be called with already-archived files after a crash.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2022-11-15 [d627ce3b7] Disallow setting archive_library and archive_command at 
-->

<listitem>
<para>
Prevent <link linkend="guc-archive-library"><varname>archive_library</varname></link> and <link linkend="guc-archive-command"><varname>archive_command</varname></link> from being set at the same time (Nathan Bossart)
</para>

<para>
Previously <varname>archive_library</varname> would override <varname>archive_command</varname>.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-11-21 [51b5834cd] Provide options for postmaster to kill child processes w
-->

<listitem>
<para>
Allow the postmaster to terminate children with an abort signal (Tom Lane)
</para>

<para>
This allows collection of a core dump for a stuck child process.
This is controlled by <link linkend="guc-send-abort-for-crash"><varname>send_abort_for_crash</varname></link> and <link linkend="guc-send-abort-for-kill"><varname>send_abort_for_kill</varname></link>.
The postmaster's <option>-T</option> switch is now the same as setting <varname>send_abort_for_crash</varname>.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-11-21 [51b5834cd] Provide options for postmaster to kill child processes w
-->

<listitem>
<para>
Remove the non-functional postmaster <option>-n</option> option (Tom Lane)
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2023-01-20 [6e2775e4d] Add new GUC reserved_connections.
-->

<listitem>
<para>
Allow the server to reserve backend slots for roles with <link linkend="predefined-roles"><literal>pg_use_reserved_connections</literal></link> membership (Nathan Bossart)
</para>

<para>
The number of reserved slots is set by server variable <link linkend="guc-reserved-connections"><varname>reserved_connections</varname></link>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-09-17 [fdd8937c0] Fix huge_pages on Windows
-->

<listitem>
<para>
Allow <link linkend="guc-huge-pages">huge pages</link> to work on newer versions of <systemitem class="osname">Windows 10</systemitem> (Thomas Munro)
</para>

<para>
This adds the special handling required to enable huge pages on newer versions of <systemitem class="osname">Windows 10</systemitem>.
</para>
</listitem>

<!--
Author: Thomas Munro <tmunro@postgresql.org>
2023-04-08 [d4e71df6d] Add io_direct setting (developer-only).
Author: Thomas Munro <tmunro@postgresql.org>
2023-05-15 [319bae9a8] Rename io_direct to debug_io_direct.
-->

<listitem>
<para>
Add <link linkend="guc-debug-io-direct"><varname>debug_io_direct</varname></link> setting for developer usage (Thomas Munro, Andres Freund, Bharath Rupireddy)
</para>

<para>
While primarily for developers, <link linkend="guc-wal-sync-method"><literal>wal_sync_method=open_sync</literal></link>/<literal>open_datasync</literal> has been modified to not use direct <acronym>I/O</acronym> with <literal>wal_level=minimal</literal>;  this is now enabled with <literal>debug_io_direct=wal</literal>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-12-20 [cca186348] Add pg_dissect_walfile_name()
Author: Michael Paquier <michael@paquier.xyz>
2022-12-23 [13e0d7a60] Rename pg_dissect_walfile_name() to pg_split_walfile_nam
-->

<listitem>
<para>
Add function <link linkend="functions-admin-backup-table"><function>pg_split_walfile_name()</function></link> to report the segment and timeline values of <acronym>WAL</acronym> file names (Bharath Rupireddy)
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4 id="release-16-pg-hba">
     <title><link linkend="auth-pg-hba-conf">pg_hba.conf</link></title>

     <itemizedlist>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-10-24 [8fea86830] Add support for regexps on database and user entries in
-->

<listitem>
<para>
Add support for regular expression matching on database and role entries in <filename>pg_hba.conf</filename> (Bertrand Drouvot)
</para>

<para>
Regular expression patterns are prefixed with a slash.  Database and role names that begin with slashes need to be double-quoted if referenced in <filename>pg_hba.conf</filename>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-01-20 [efb6f4a4f] Support the same patterns for pg-user in pg_ident.conf a
-->

<listitem>
<para>
Improve user-column handling of <link linkend="runtime-config-file-locations"><filename>pg_ident.conf</filename></link> to match <filename>pg_hba.conf</filename> (Jelte Fennema)
</para>

<para>
Specifically, add support for <literal>all</literal>, role membership with <literal>+</literal>, and regular expressions with a leading slash.  Any user name that matches these patterns must be double-quoted.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-11-24 [a54b658ce] Add support for file inclusions in HBA and ident configu
-->

<listitem>
<para>
Allow include files in <filename>pg_hba.conf</filename> and <filename>pg_ident.conf</filename> (Julien Rouhaud)
</para>

<para>
These are controlled by <literal>include</literal>, <literal>include_if_exists</literal>, and <literal>include_dir</literal>.  System views <link linkend="view-pg-hba-file-rules"><structname>pg_hba_file_rules</structname></link> and <link linkend="view-pg-ident-file-mappings"><structname>pg_ident_file_mappings</structname></link> now display the file name.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-07-27 [de3f0e3fe] Eliminate fixed token-length limit in hba.c.
-->

<listitem>
<para>
Allow <filename>pg_hba.conf</filename> tokens to be of unlimited length (Tom Lane)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-10-26 [c591300a8] Add rule_number to pg_hba_file_rules and map_number to p
-->

<listitem>
<para>
Add rule and map numbers to the system view <link linkend="view-pg-hba-file-rules"><structname>pg_hba_file_rules</structname></link> (Julien Rouhaud)
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4 id="release-16-localization">
     <title><link linkend="charset">Localization</link></title>

     <itemizedlist>

<!--
Author: Jeff Davis <jdavis@postgresql.org>
2023-03-10 [c45dc7ffb] initdb: derive encoding from locale for ICU; similar to
-->

<listitem>
<para>
Determine the <acronym>ICU</acronym> default locale from the environment (Jeff Davis)
</para>

<para>
However, <link linkend="locale-providers"><acronym>ICU</acronym></link> doesn't support the C locale so <literal>UTF-8</literal> is used in such cases.  Previously the default was always <literal>UTF-8</literal>.
</para>
</listitem>

<!--
Author: Jeff Davis <jdavis@postgresql.org>
Date:   Fri Jun 16 10:27:32 2023 -0700
-->

<listitem>
<para>
Have <link linkend="sql-createdatabase"><command>CREATE DATABASE</command></link> and <link linkend="sql-createcollation"><command>CREATE COLLATION</command></link>'s <literal>LOCALE</literal> options, and <link linkend="app-initdb"><application>initdb</application></link> and <link linkend="app-createdb"><application>createdb</application></link> <option>--locale</option> options, control non-<application>libc</application> collation providers (Jeff Davis)
</para>

<para>
Previously they only controlled <application>libc</application> providers.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-03-10 [0d21d4b9b] Add standard collation UNICODE
-->

<listitem>
<para>
Add predefined collations <literal>unicode</literal> and <literal>ucs_basic</literal> (Peter Eisentraut)
</para>

<para>
This only works if <acronym>ICU</acronym> support is enabled.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-03-08 [30a53b792] Allow tailoring of ICU locales with custom rules
-->

<listitem>
<para>
Allow custom <acronym>ICU</acronym> collation rules to be created (Peter Eisentraut)
</para>

<para>
This is done using <link linkend="sql-createcollation"><command>CREATE COLLATION</command></link>'s new <literal>RULES</literal> clause, as well as new options for <link linkend="sql-createdatabase"><command>CREATE DATABASE</command></link>, <link linkend="app-createdb"><application>createdb</application></link>, and <link linkend="app-initdb"><application>initdb</application></link>.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-01-03 [bf03cfd16] Windows support in pg_import_system_collations
-->

<listitem>
<para>
Allow <systemitem class="osname">Windows</systemitem> to import system locales automatically (Juan José Santamaría Flecha)
</para>

<para>
Previously, only <acronym>ICU</acronym> locales could be imported on <systemitem class="osname">Windows</systemitem>.
</para>
</listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3 id="release-16-logical">
    <title><link linkend="logical-replication">Logical Replication</link></title>

    <itemizedlist>

<!--
Author: Andres Freund <andres@anarazel.de>
2023-04-08 [0fdab27ad] Allow logical decoding on standbys
Author: Andres Freund <andres@anarazel.de>
2023-04-07 [be87200ef] Support invalidating replication slots due to horizon an
Author: Andres Freund <andres@anarazel.de>
2023-04-08 [26669757b] Handle logical slot conflicts on standby
-->

<listitem>
<para>
Allow <link linkend="logicaldecoding">logical decoding</link> on standbys (Bertrand Drouvot, Andres Freund, Amit Khandekar)
</para>

<para>
Snapshot <acronym>WAL</acronym> records are required for logical slot creation but cannot be created on standbys.
To avoid delays, the new function <link linkend="functions-snapshot-synchronization-table"><function>pg_log_standby_snapshot()</function></link> allows creation of such records.
</para>
</listitem>

<!--
Author: Amit Kapila <akapila@postgresql.org>
2022-12-26 [5de94a041] Add 'logical_decoding_mode' GUC.
Author: Amit Kapila <akapila@postgresql.org>
2023-01-30 [1e8b61735] Rename GUC logical_decoding_mode to logical_replication_
Author: Amit Kapila <akapila@postgresql.org>
2023-02-02 [9f2213a7c] Allow the logical_replication_mode to be used on the sub
-->

<listitem>
<para>
Add server variable to control how logical decoding publishers transfer changes and how subscribers apply them (Shi Yu)
</para>

<para>
The variable is <link linkend="guc-logical-replication-mode"><varname>logical_replication_mode</varname></link>.
</para>
</listitem>

<!--
Author: Amit Kapila <akapila@postgresql.org>
2023-03-23 [ecb696527] Allow logical replication to copy tables in binary forma
-->

<listitem>
<para>
Allow logical replication initial table synchronization to copy rows in binary format (Melih Mutlu)
</para>

<para>
This is only possible for subscriptions marked as binary.
</para>
</listitem>

<!--
Author: Amit Kapila <akapila@postgresql.org>
2023-01-09 [216a78482] Perform apply of large transactions by parallel workers.
Author: Amit Kapila <akapila@postgresql.org>
2023-01-10 [cd06ccd78] Document the newly added wait events added by commit 216
Author: Amit Kapila <akapila@postgresql.org>
2023-02-16 [fce003cfd] Add a new wait state and use it when sending data in the
-->

<listitem>
<para>
Allow parallel application of logical replication (Hou Zhijie, Wang Wei, Amit Kapila)
</para>

<para>
The <link linkend="sql-createsubscription"><command>CREATE SUBSCRIPTION</command></link> <option>STREAMING</option> option now supports <literal>parallel</literal> to enable application of large transactions by parallel workers.  The number of parallel workers is controlled by
the new server variable <link linkend="guc-max-parallel-apply-workers-per-subscription"><varname>max_parallel_apply_workers_per_subscription</varname></link>. Wait events <link linkend="wait-event-activity-table"><literal>LogicalParallelApplyMain</literal></link>, <literal>LogicalParallelApplyStateChange</literal>, and <literal>LogicalApplySendData</literal> were also added.  Column <structfield>leader_pid</structfield> was
added to system view <link linkend="monitoring-pg-stat-subscription"><structname>pg_stat_subscription</structname></link> to track parallel activity.
</para>
</listitem>

<!--
Author: Amit Kapila <akapila@postgresql.org>
2023-03-15 [89e46da5e] Allow the use of indexes other than PK and REPLICA IDENT
-->

<listitem>
<para>
Improve performance for <link linkend="logical-replication-architecture">logical replication apply</link> without a primary key (Onder Kalaci, Amit Kapila)
</para>

<para>
Specifically, <literal>REPLICA IDENTITY FULL</literal> can now use btree indexes rather than sequentially scanning the table to find matches.
</para>
</listitem>

<!--
Author: Amit Kapila <akapila@postgresql.org>
2022-07-21 [366283961] Allow users to skip logical replication of data having o
Author: Amit Kapila <akapila@postgresql.org>
2022-09-08 [875693019] Raise a warning if there is a possibility of data from m
-->

<listitem>
<para>
Allow logical replication subscribers to process only changes that have no origin (Vignesh C, Amit Kapila)
</para>

<para>
This can be used to avoid replication loops.  This is controlled by the new <literal>CREATE SUBSCRIPTION ... ORIGIN</literal> option.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2023-04-04 [1e10d49b6] Perform logical replication actions as the table owner.
Author: Robert Haas <rhaas@postgresql.org>
2023-04-04 [482675987] Add a run_as_owner option to subscriptions.
-->

<listitem>
<para>
Perform logical replication <link linkend="sql-select"><command>SELECT</command></link> and <acronym>DML</acronym> actions as the table owner (Robert Haas)
</para>

<para>
This improves security and now requires subscription owners to be either superusers or to have <link linkend="sql-set-role"><command>SET ROLE</command></link> permissions on all tables in the replication set.  The previous behavior of performing all operations
as the subscription owner can be enabled with the subscription <link linkend="sql-createsubscription"><option>run_as_owner</option></link> option.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-22 [5a3a95385] Track logrep apply workers' last start times to avoid us
-->

<listitem>
<para>
Have <link linkend="guc-wal-retrieve-retry-interval"><varname>wal_retrieve_retry_interval</varname></link> operate on a per-subscription basis (Nathan Bossart)
</para>

<para>
Previously the retry time was applied globally.  This also adds wait events <link linkend="wait-event-lwlock-table">><literal>LogicalRepLauncherDSA</literal></link> and <literal>LogicalRepLauncherHash</literal>.
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-utility">
    <title>Utility Commands</title>

    <itemizedlist>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-24 [3c05284d8] Invent GENERIC_PLAN option for EXPLAIN.
-->

<listitem>
<para>
Add <link linkend="sql-explain"><command>EXPLAIN</command></link> option <literal>GENERIC_PLAN</literal> to display the generic plan for a parameterized query (Laurenz Albe)
</para>
</listitem>

<!--
Author: Andrew Dunstan <andrew@dunslane.net>
2023-03-13 [9f8377f7a] Add a DEFAULT option to COPY  FROM
-->

<listitem>
<para>
Allow a <link linkend="sql-copy"><command>COPY FROM</command></link> value to map to a column's <literal>DEFAULT</literal> (Israel Barth Rubio)
</para>
</listitem>

<!--
Author: Etsuro Fujita <efujita@postgresql.org>
2022-10-13 [97da48246] Allow batch insertion during COPY into a foreign table.
-->

<listitem>
<para>
Allow <link linkend="sql-copy"><command>COPY</command></link> into foreign tables to add rows in batches (Andrey Lepikhov, Etsuro Fujita)
</para>

<para>
This is controlled by the <link linkend="postgres-fdw"><application>postgres_fdw</application></link> option <link linkend="postgres-fdw-options-cost-estimation"><option>batch_size</option></link>.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2022-07-13 [784cedda0] Allow specifying STORAGE attribute for a new table
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-11-10 [b9424d014] Support writing "CREATE/ALTER TABLE ... SET STORAGE DEFA
-->

<listitem>
<para>
Allow the <literal>STORAGE</literal> type to be specified by <link linkend="sql-createtable"><command>CREATE TABLE</command></link> (Teodor Sigaev, Aleksander Alekseev)
</para>

<para>
Previously only <link linkend="sql-altertable"><command>ALTER TABLE</command></link> could control this.
</para>
</listitem>

<!--
Author: Fujii Masao <fujii@postgresql.org>
2022-07-12 [3b00a944a] Support TRUNCATE triggers on foreign tables.
-->

<listitem>
<para>
Allow <link linkend="sql-createtrigger">truncate triggers</link> on foreign tables (Yugo Nagata)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-03-06 [4211fbd84] Add PROCESS_MAIN to VACUUM
-->

<listitem>
<para>
Allow <link linkend="sql-vacuum"><command>VACUUM</command></link> and <link linkend="app-vacuumdb"><application>vacuumdb</application></link> to only process <link linkend="storage-toast"><literal>TOAST</literal></link> tables (Nathan Bossart)
</para>

<para>
This is accomplished by having <link linkend="sql-vacuum"><command>VACUUM</command></link> turn off <literal>PROCESS_MAIN</literal> or by <link linkend="app-vacuumdb"><application>vacuumdb</application></link> using the <option>--no-process-main</option> option.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-06 [a46a7011b] Add options to control whether VACUUM runs vac_update_da
-->

<listitem>
<para>
Add <link linkend="sql-vacuum"><command>VACUUM</command></link> options to skip or update all <link linkend="vacuum-for-wraparound">frozen</link> statistics (Tom Lane, Nathan Bossart)
</para>

<para>
The options are <literal>SKIP_DATABASE_STATS</literal> and <literal>ONLY_DATABASE_STATS</literal>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-07-19 [2cbc3c17a] Rework logic and simplify syntax of REINDEX DATABASE/SYS
Author: Michael Paquier <michael@paquier.xyz>
2022-07-26 [0a5f06b84] Fix a few issues with REINDEX grammar
-->

<listitem>
<para>
Change <link linkend="sql-reindex"><command>REINDEX DATABASE</command></link> and <link linkend="sql-reindex"><command>REINDEX SYSTEM</command></link> to no longer require an argument (Simon Riggs)
</para>

<para>
Previously the database name had to be specified.
</para>
</listitem>

<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2022-07-21 [624aa2a13] Make the name optional in CREATE STATISTICS.
-->

<listitem>
<para>
Allow <link linkend="sql-createstatistics"><command>CREATE STATISTICS</command></link> to generate a statistics name if none is specified (Simon Riggs)
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-datatypes">
    <title>Data Types</title>

    <itemizedlist>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2022-12-14 [6fcda9aba] Non-decimal integer literals
-->

<listitem>
<para>
Allow non-decimal <link linkend="sql-syntax-bit-strings">integer literals</link> (Peter Eisentraut)
</para>

<para>
For example, <literal>0x42F</literal>, <literal>0o273</literal>, and <literal>0b100101</literal>.
</para>
</listitem>

<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2023-01-23 [6dfacbf72] Add non-decimal integer support to type numeric.
-->

<listitem>
<para>
Allow <link linkend="datatype-numeric"><type>NUMERIC</type></link> to process hexadecimal, octal, and binary integers of any size (Dean Rasheed)
</para>

<para>
Previously only unquoted eight-byte integers were supported with these non-decimal bases.
</para>
</listitem>

<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2023-02-04 [faff8f8e4] Allow underscores in integer and numeric constants.
-->

<listitem>
<para>
Allow underscores in integer and numeric <link linkend="sql-syntax-bit-strings">constants</link> (Peter Eisentraut, Dean Rasheed)
</para>

<para>
This can improve readability for long strings of digits.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-01 [2ceea5adb] Accept "+infinity" in date and timestamp[tz] input.
-->

<listitem>
<para>
Accept the spelling <literal>+infinity</literal> in datetime input (Vik Fearing)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-09 [bcc704b52] Reject combining "epoch" and "infinity" with other datet
-->

<listitem>
<para>
Prevent the specification of <literal>epoch</literal> and <literal>infinity</literal> together with other fields in datetime strings (Joseph Koshakow)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-16 [5b3c59535] Tighten error checks in datetime input, and remove bogus
-->

<listitem>
<para>
Remove undocumented support for date input in the form
<literal>Y<replaceable>year</replaceable>M<replaceable>month</replaceable>D<replaceable>day</replaceable></literal>
(Joseph Koshakow)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-12-09 [1939d2628] Add test scaffolding for soft error reporting from input
Author: Michael Paquier <michael@paquier.xyz>
2023-02-28 [b8da37b3a] Rework pg_input_error_message(), now renamed pg_input_er
-->

<listitem>
<para>
Add functions <link linkend="functions-info-validity-table"><function>pg_input_is_valid()</function></link> and <function>pg_input_error_info()</function> to check for type conversion errors (Tom Lane)
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-general">
    <title>General Queries</title>

    <itemizedlist>

<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2022-07-20 [bcedd8f5f] Make subquery aliases optional in the FROM clause.
-->

<listitem>
<para>
Allow subqueries in the <literal>FROM</literal> clause to omit aliases (Dean Rasheed)
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-03-05 [102a5c164] SQL JSON path enhanced numeric literals
-->

<listitem>
<para>
Add support for enhanced numeric literals in <acronym>SQL/JSON</acronym> paths (Peter Eisentraut)
</para>

<para>
For example, allow hexadecimal, octal, and binary integers and underscores between digits.
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-functions">
    <title>Functions</title>

    <itemizedlist>

<!--
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
2023-03-29 [7081ac46a] SQL/JSON: add standard JSON constructor functions
-->

<listitem>
<para>
Add <acronym>SQL/JSON</acronym> constructors (Nikita Glukhov, Teodor Sigaev, Oleg Bartunov, Alexander Korotkov, Amit Langote)
</para>

<para>
The new functions <link linkend="functions-json-creation-table"><function>JSON_ARRAY()</function></link>, <link linkend="functions-aggregate-table"><function>JSON_ARRAYAGG()</function></link>, <function>JSON_OBJECT()</function>, and <function>JSON_OBJECTAGG()</function> are part of the <acronym>SQL</acronym> standard.
</para>
</listitem>

<!--
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
2023-03-31 [6ee30209a] SQL/JSON: support the IS JSON predicate
-->

<listitem>
<para>
Add <acronym>SQL/JSON</acronym> object checks (Nikita Glukhov, Teodor Sigaev, Oleg Bartunov, Alexander Korotkov, Amit Langote, Andrew Dunstan)
</para>

<para>
The <link linkend="functions-sqljson-misc"><literal>IS JSON</literal></link> checks include checks for values, arrays, objects, scalars, and unique keys.
</para>
</listitem>

<!--
Author: John Naylor <john.naylor@postgresql.org>
2022-09-02 [0a8de93a4] Speed up lexing of long JSON strings
-->

<listitem>
<para>
Allow <acronym>JSON</acronym> string parsing to use vector operations (John Naylor)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-19 [5a617d75d] Fix ts_headline() to handle ORs and phrase queries more 
-->

<listitem>
<para>
Improve the handling of full text highlighting function <link linkend="textsearch-functions-table"><function>ts_headline()</function></link> for <literal>OR</literal> and <literal>NOT</literal> expressions (Tom Lane)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-18 [75bd846b6] Add functions to do timestamptz arithmetic in a non-defa
-->

<listitem>
<para>
Add functions to add, subtract, and generate <type>timestamptz</type> values in a specified time zone (Przemyslaw Sztoch, Gurjeet Singh)
</para>

<para>
The functions are <link linkend="functions-datetime-table"><function>date_add()</function></link>, <function>date_subtract()</function>, and <link linkend="functions-srf-series"><function>generate_series()</function></link>.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-11-12 [533e02e92] Fix volatility marking of timestamptz_trunc_zone.
-->

<listitem>
<para>
Change <link linkend="functions-datetime-table"><function>date_trunc(unit, timestamptz, time_zone)</function></link> to be an immutable function (Przemyslaw Sztoch)
</para>

<para>
This allows the creation of expression indexes using this function.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-09-29 [0823d061b] Introduce SYSTEM_USER
-->

<listitem>
<para>
Add server variable <link linkend="functions-info-session-table"><literal>SYSTEM_USER</literal></link> (Bertrand Drouvot)
</para>

<para>
This reports the authentication method and its authenticated user.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-04-07 [888f2ea0a] Add array_sample() and array_shuffle() functions.
-->

<listitem>
<para>
Add functions <link linkend="array-functions-table"><function>array_sample()</function></link> and <function>array_shuffle()</function> (Martin Kalcher)
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-02-22 [2ddab010c] Implement ANY_VALUE aggregate
-->

<listitem>
<para>
Add aggregate function <link linkend="functions-aggregate-table"><function>ANY_VALUE()</function></link> which returns any value from a set (Vik Fearing)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-09 [38d81760c] Invent random_normal() to provide normally-distributed r
-->

<listitem>
<para>
Add function <link linkend="functions-math-random-table"><function>random_normal()</function></link> to supply normally-distributed random numbers (Paul Ramsey)
</para>
</listitem>

<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2023-03-14 [d5d574146] Add support for the error functions erf() and erfc().
-->

<listitem>
<para>
Add error function <link linkend="functions-math-func-table"><function>erf()</function></link> and its complement <function>erfc()</function> (Dean Rasheed)
</para>
</listitem>

<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2022-10-20 [40c7fcbbe] Improve the accuracy of numeric power() for integer expo
-->

<listitem>
<para>
Improve the accuracy of numeric <link linkend="functions-math-func-table"><function>power()</function></link> for integer exponents (Dean Rasheed)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-15 [483bdb2af] Support [NO] INDENT option in XMLSERIALIZE().
-->

<listitem>
<para>
Add <link linkend="datatype-xml-creating"><function>XMLSERIALIZE()</function></link> option <literal>INDENT</literal> to pretty-print its output (Jim Jones)
</para>
</listitem>

<!--
Author: Jeff Davis <jdavis@postgresql.org>
2022-10-31 [10932ed5e] Enable pg_collation_actual_version() to work on the defa
-->

<listitem>
<para>
Change <link linkend="functions-admin-collation"><function>pg_collation_actual_version()</function></link> to return a reasonable value for the default collation (Jeff Davis)
</para>

<para>
Previously it returned <literal>NULL</literal>.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-07-29 [283129e32] Support pg_read_[binary_]file (filename, missing_ok).
-->

<listitem>
<para>
Allow <link linkend="functions-admin-genfile-table"><function>pg_read_file()</function></link> and <function>pg_read_binary_file()</function> to ignore missing files (Kyotaro Horiguchi)
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-03-07 [ce1215d9b] Add support for unit "B" to pg_size_bytes()
-->

<listitem>
<para>
Add byte specification (<literal>B</literal>) to <link linkend="functions-admin-dbsize"><function>pg_size_bytes()</function></link> (Peter Eisentraut)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-12-27 [3ea7329c9] Simplify the implementations of the to_reg* functions.
-->

<listitem>
<para>
Allow <link linkend="functions-info-catalog-table"><function>to_reg</function></link>* functions to accept numeric <acronym>OID</acronym>s as input (Tom Lane)
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-plpgsql">
    <title><link linkend="plpgsql">PL/pgSQL</link></title>

    <itemizedlist>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-04-04 [d3d53f955] Add a way to get the current function's OID in pl/pgsql.
-->

<listitem>
<para>
Add the ability to get the current function's <acronym>OID</acronym> in <application>PL/pgSQL</application> (Pavel Stehule)
</para>

<para>
This is accomplished with <link linkend="plpgsql-statements-diagnostics"><command>GET DIAGNOSTICS variable = PG_ROUTINE_OID</command></link>.
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-libpq">
    <title><link linkend="libpq">libpq</link></title>

    <itemizedlist>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-03-14 [3a465cc67] libpq: Add support for require_auth to control authorize
-->

<listitem>
<para>
Add <application>libpq</application> connection option <link linkend="libpq-connect-require-auth"><option>require_auth</option></link> to specify a list of acceptable authentication methods (Jacob Champion)
</para>

<para>
This can also be used to disallow certain authentication methods.
</para>
</listitem>

<!--
Author: Daniel Gustafsson <dgustafsson@postgresql.org>
2023-03-29 [7f5b19817] Support connection load balancing in libpq
Author: Fujii Masao <fujii@postgresql.org>
2023-04-21 [0a16512d4] doc: Add documentation for PGLOADBALANCEHOSTS environmen
-->

<listitem>
<para>
Allow multiple <application>libpq</application>-specified hosts to be randomly selected (Jelte Fennema)
</para>

<para>
This is enabled with <link linkend="libpq-connect-load-balance-hosts"><literal>load_balance_hosts=random</literal></link> and can be used for load balancing.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-03-24 [36f40ce2d] libpq: Add sslcertmode option to control client certific
-->

<listitem>
<para>
Add <application>libpq</application> option <link linkend="libpq-connect-sslcertmode"><option>sslcertmode</option></link> to control transmission of the client certificate (Jacob Champion)
</para>

<para>
The option values are <literal>disable</literal>, <literal>allow</literal>, and <literal>require</literal>.
</para>
</listitem>

<!--
Author: Daniel Gustafsson <dgustafsson@postgresql.org>
2023-04-05 [8eda73146] Allow to use system CA pool for certificate verification
-->

<listitem>
<para>
Allow <application>libpq</application> to use the system certificate pool for certificate verification (Jacob Champion, Thomas Habets)
</para>

<para>
This is enabled with <link linkend="libpq-connect-sslrootcert"><literal>sslrootcert=system</literal></link>, which also enables <link linkend="libpq-connect-sslmode"><literal>sslmode=verify-full</literal></link>.
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-client-apps">
    <title>Client Applications</title>

    <itemizedlist>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-07-12 [83f1c7b74] Fix ECPG's handling of type names that match SQL keyword
-->

<listitem>
<para>
Allow <link linkend="ecpg"><command>ECPG</command></link> variable declarations to use typedef names that match unreserved <acronym>SQL</acronym> keywords (Tom Lane)
</para>

<para>
This change does prevent keywords which match C typedef names from being processed as keywords in later <command>EXEC SQL</command> blocks.
</para>
</listitem>

    </itemizedlist>

    <sect4 id="release-16-psql">
     <title><xref linkend="app-psql"/></title>

     <itemizedlist>

<!--
Author: Andrew Dunstan <andrew@dunslane.net>
2022-07-25 [a45388d6e] Add xheader_width pset option to psql
-->

<listitem>
<para>
Allow <application>psql</application> to control the maximum width of header lines in expanded format (Platon Pronko)
</para>

<para>
This is controlled by <link linkend="app-psql-meta-command-pset-xheader-width"><option>xheader_width</option></link>.
</para>
</listitem>

<!--
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2023-01-07 [d913928c9] psql: Add support for \dpS and \zS.
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-07-19 [d65ddaca9] Add psql \drg command to display role
-->

<listitem>
<para>
Allow <application>psql</application>'s access privilege commands to show system objects (Nathan Bossart, Pavel Luzanov)
</para>

<para>
The options are <link linkend="app-psql-meta-command-dp-lc"><command>\dpS</command></link>, <link linkend="app-psql-meta-command-z"><command>\zS</command></link>, and <link linkend="app-psql-meta-command-drg"><command>\drg</command></link>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-11-08 [bd95816f7] psql: Add information in \d+ about foreign partitions an
-->

<listitem>
<para>
Add <literal>FOREIGN</literal> designation to <application>psql</application> <link linkend="app-psql-meta-command-d"><command>\d+</command></link> for foreign table children and partitions (Ian Lawrence Barwick)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-02 [3dfae91f7] Show "internal name" not "source code" in psql's \df+ co
-->

<listitem>
<para>
Prevent <link linkend="app-psql-meta-command-df-uc"><command>\df+</command></link> from showing function source code (Isaac Morland)
</para>

<para>
Function bodies are more easily viewed with <link linkend="app-psql-meta-command-sf"><command>\sf</command></link>.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2022-11-15 [5b66de343] psql: Add command to use extended query protocol
-->

<listitem>
<para>
Allow <application>psql</application> to submit queries using the extended query protocol (Peter Eisentraut)
</para>

<para>
Passing arguments to such queries is done using the new <application>psql</application> <link linkend="app-psql-meta-command-bind"><command>\bind</command></link> command.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-04-06 [00beecfe8] psql: add an optional execution-count limit to \watch.
-->

<listitem>
<para>
Allow <application>psql</application> <link linkend="app-psql-meta-command-watch"><command>\watch</command></link> to limit the number of executions (Andrey Borodin)
</para>

<para>
The <command>\watch</command> options can now be named when specified.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-03-16 [6f9ee74d4] Improve handling of psql \watch's interval argument
-->

<listitem>
<para>
Detect invalid values for <application>psql</application> <link linkend="app-psql-meta-command-watch"><command>\watch</command></link>, and allow zero to specify no delay (Andrey Borodin)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-21 [b0d8f2d98] Add SHELL_ERROR and SHELL_EXIT_CODE magic variables to p
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-04-06 [31ae2aa9d] psql: set SHELL_ERROR and SHELL_EXIT_CODE in more places
-->

<listitem>
<para>
Allow <application>psql</application> scripts to obtain the exit status of shell commands and queries
(Corey Huinker, Tom Lane)
</para>

<para>
The new <application>psql</application> control variables are <link linkend="app-psql-variables-shell-error"><literal>SHELL_ERROR</literal></link> and <link linkend="app-psql-variables-shell-exit-code"><literal>SHELL_EXIT_CODE</literal></link>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-08-15 [f6c750d31] Improve tab completion of ALTER TYPE in psql
Author: Michael Paquier <michael@paquier.xyz>
2022-09-06 [4cbe57974] Add psql tab compression for SET COMPRESSION with ALTER 
Author: Michael Paquier <michael@paquier.xyz>
2022-09-10 [6afcab6ac] Add psql tab compression for ALTER TABLE .. { OF | NOT O
Author: Michael Paquier <michael@paquier.xyz>
2022-10-05 [9aa58d48f] Add a few new patterns to the tab completion of psql
Author: Michael Paquier <michael@paquier.xyz>
2022-10-24 [3cf2f7af7] Improve tab completion for ALTER STATISTICS &lt;name&gt; SET i
Author: Peter Eisentraut <peter@eisentraut.org>
2022-11-01 [2ea5de296] psql: Improve tab completion for ALTER TABLE on identity
Author: Michael Paquier <michael@paquier.xyz>
2022-11-18 [07f7237c2] psql: Improve tab completion for GRANT/REVOKE
Author: Michael Paquier <michael@paquier.xyz>
2022-12-12 [9d0cf5749] Add support for GRANT SET in psql tab completion
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
2023-01-06 [a3bc631ea] Improve tab completion for ALTER FUNCTION/PROCEDURE/ROUT
Author: Michael Paquier <michael@paquier.xyz>
2023-01-12 [2ff5ca86e] Add support for tab completion after ALTER EXTENSION ADD
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-04-19 [9e1e9d656] Add missed case for tab completion of GRANT/REVOKE MAINT
Author: Amit Kapila <akapila@postgresql.org>
2023-04-07 [96c498d2f] Add tab-completion for newly added SUBSCRIPTION options.
-->

<listitem>
<para>
Various <application>psql</application> tab completion improvements (Vignesh C, Aleksander Alekseev, Dagfinn Ilmari Mannsåker, Shi Yu, Michael Paquier, Ken Kato, Peter Smith)
</para>
</listitem>

     </itemizedlist>

    </sect4>

    <sect4 id="release-16-pgdump">
     <title><link linkend="app-pgdump"><application>pg_dump</application></link></title>

     <itemizedlist>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-14 [a563c24c9] Allow pg_dump to include/exclude child tables automatica
-->

<listitem>
<para>
Add <application>pg_dump</application> control of dumping child tables and partitions (Gilles Darold)
</para>

<para>
The new options are <option>--table-and-children</option>, <option>--exclude-table-and-children</option>, and <option>--exclude-table-data-and-children</option>.
</para>
</listitem>

<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2023-02-23 [0da243fed] Add LZ4 compression to pg_dump
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2023-04-01 [0070b66fe] pg_dump: Use only LZ4 frame format for compression
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2023-04-05 [84adc8e20] pg_dump: Add support for zstd compression-->

<listitem>
<para>
Add <application>LZ4</application> and <application>Zstandard</application> compression to <application>pg_dump</application> (Georgios Kokolatos, Justin Pryzby)
</para>
</listitem>

<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2023-04-06 [2820adf77] Support long distance matching for zstd compression
-->

<listitem>
<para>
Allow <application>pg_dump</application> and <link linkend="app-pgbasebackup"><application>pg_basebackup</application></link> to use <literal>long</literal> mode for compression (Justin Pryzby)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-12-02 [5e73a6048] Switch pg_dump to use compression specifications
-->

<listitem>
<para>
Improve <application>pg_dump</application> to accept a more consistent compression syntax (Georgios Kokolatos)
</para>

<para>
Options like <option>--compress=gzip:5</option>.
</para>
</listitem>

     </itemizedlist>

    </sect4>

   </sect3>

   <sect3 id="release-16-server-apps">
    <title>Server Applications</title>

    <itemizedlist>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us> 2023-03-22
[3e51b278d] Add "-c name=value" switch to initdb.
-->

<listitem>
<para>
Add <link linkend="app-initdb"><application>initdb</application></link> option to set server variables for the duration of <application>initdb</application> and all future server starts (Tom Lane)
</para>

<para>
The option is <option>-c name=value</option>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-07-13 [08951a7c9] createuser: Add support for more clause types through ne
Author: Nathan Bossart <nathan@postgresql.org>
2023-05-21 [2dcd1578c] Rename some createuser options.
-->

<listitem>
<para>
Add options to <link linkend="app-createuser"><application>createuser</application></link> to control more user options (Shinya Kato)
</para>

<para>
Specifically, the new options control the valid-until date, bypassing of row-level security, and role membership.
</para>
</listitem>

<!--
Author: Nathan Bossart <nathan@postgresql.org>
2023-05-21 [2dcd1578c] Rename some createuser options.
Author: Nathan Bossart <nathan@postgresql.org>
2023-05-23 [381d19b3e] Document deprecated createuser option.
-->

<listitem>
<para>
Deprecate <link linkend="app-createuser"><application>createuser</application></link> option <option>--role</option> (Nathan Bossart)
</para>

<para>
This option could be easily confused with new <application>createuser</application> role membership options, so option <option>--member-of</option> has been added with the same functionality.
The <option>--role</option> option can still be used.
</para>
</listitem>

<!--
Author: Andrew Dunstan <andrew@dunslane.net>
2022-07-31 [7781f4e3e] Add - -schema and - -exclude-schema options to vacuumdb.
-->

<listitem>
<para>
Allow control of <link linkend="app-vacuumdb"><application>vacuumdb</application></link> schema processing (Gilles Darold)
</para>

<para>
These are controlled by options <option>--schema</option> and <option>--exclude-schema</option>.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-06 [a46a7011b] Add options to control whether VACUUM runs vac_update_da
-->

<listitem>
<para>
Use new <link linkend="sql-vacuum"><command>VACUUM</command></link> options to improve the performance of <link linkend="app-vacuumdb"><application>vacuumdb</application></link> (Tom Lane, Nathan Bossart)
</para>
</listitem>

<!--
Author: Jeff Davis <jdavis@postgresql.org>
2023-03-09 [9637badd9] pg_upgrade: copy locale and encoding information to new 
-->

<listitem>
<para>
Have <link linkend="pgupgrade"><application>pg_upgrade</application></link> set the new cluster's locale and encoding (Jeff Davis)
</para>

<para>
This removes the requirement that the new cluster be created with the same locale and encoding settings.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2022-12-16 [746915c68] pg_upgrade: Add - -copy option
-->

<listitem>
<para>
Add <link linkend="pgupgrade"><application>pg_upgrade</application></link> option to specify the default transfer mode (Peter Eisentraut)
</para>

<para>
The option is <option>--copy</option>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-11-30 [d18655cc0] Refactor code parsing compression option values (-Z/- -co
-->

<listitem>
<para>
Improve <link linkend="app-pgbasebackup"><application>pg_basebackup</application></link> to accept numeric compression options (Georgios Kokolatos, Michael Paquier)
</para>

<para>
Options like <option>--compress=server-5</option> are now supported.
</para>
</listitem>

<!--
Author: Robert Haas <rhaas@postgresql.org>
2023-04-18 [363e8f911] Fix pg_basebackup with in-place tablespaces some more.
-->

<listitem>
<para>
Fix <link linkend="app-pgbasebackup"><application>pg_basebackup</application></link> to handle tablespaces stored in the <envar>PGDATA</envar> directory (Robert Haas)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-12-27 [d497093cb] pg_waldump: Add - -save-fullpage=PATH to save full page i
-->

<listitem>
<para>
Add <link linkend="pgwaldump"><application>pg_waldump</application></link> option <option>--save-fullpage</option> to dump full page images (David Christensen)
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-03-21 [4c8044c04] pg_waldump: Allow hexadecimal values for -t/- -timeline o
-->

<listitem>
<para>
Allow <link linkend="pgwaldump"><application>pg_waldump</application></link> options <option>-t</option>/<option>--timeline</option> to accept hexadecimal values (Peter Eisentraut)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-02-06 [d07c2948b] Add support for progress reporting to pg_verifybackup
-->

<listitem>
<para>
Add support for progress reporting to <link linkend="app-pgverifybackup"><application>pg_verifybackup</application></link> (Masahiko Sawada)
</para>
</listitem>

<!--
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
2023-02-23 [009eeee74] pg_rewind: Fix determining TLI when server was just prom
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
2023-02-27 [0a0500207] pg_rewind: Remove notice in docs about running CHECKPOIN
-->

<listitem>
<para>
Allow <link linkend="app-pgrewind"><application>pg_rewind</application></link> to properly track timeline changes (Heikki Linnakangas)
</para>

<para>
Previously if <application>pg_rewind</application> was run after a timeline switch but before a checkpoint was issued, it might incorrectly determine that a rewind was unnecessary.
</para>
</listitem>

<!--
Author: Daniel Gustafsson <dgustafsson@postgresql.org>
2022-09-14 [8b60db774] Handle SIGTERM in pg_receivewal and pg_recvlogical
-->

<listitem>
<para>
Have <link linkend="app-pgreceivewal"><application>pg_receivewal</application></link> and <link linkend="app-pgrecvlogical"><application>pg_recvlogical</application></link> cleanly exit on <literal>SIGTERM</literal> (Christoph Berg)
</para>

<para>
This signal is often used by <application>systemd</application>.
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-source-code">
    <title>Source Code</title>

    <itemizedlist>

<!--
Author: Jeff Davis <jdavis@postgresql.org>
2023-04-18 [fcb21b3ac] Build ICU support by default.
-->

<listitem>
<para>
Build <acronym>ICU</acronym> support by default (Jeff Davis)
</para>

<para>
This removes <link linkend="installation">build flag</link> <option>--with-icu</option> and adds flag <option>--without-icu</option>.
</para>
</listitem>

<!--
Author: John Naylor <john.naylor@postgresql.org>
2022-08-04 [56f2c7b58] Support SSE2 intrinsics where available
-->

<listitem>
<para>
Add support for SSE2 (Streaming <acronym>SIMD</acronym> Extensions 2) vector operations on x86-64 architectures (John Naylor)
</para>
</listitem>

<!--
Author: John Naylor <john.naylor@postgresql.org>
2022-08-29 [82739d4a8] Use ARM Advanced SIMD (NEON) intrinsics where available
-->

<listitem>
<para>
Add support for Advanced <acronym>SIMD</acronym> (Single Instruction Multiple Data) (<acronym>NEON</acronym>) instructions on <acronym>ARM</acronym> architectures (Nathan Bossart)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-08-28 [36389a060] Enable RandomizedBaseAddress (ASLR) on Windows with MSVC
-->

<listitem>
<para>
Have <systemitem class="osname">Windows</systemitem> binaries built with <productname>MSVC</productname> use <literal>RandomizedBaseAddress</literal> (<acronym>ASLR</acronym>) (Michael Paquier)
</para>

<para>
This was already enabled on <productname>MinGW</productname> builds.
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2022-07-17 [089480c07] Default to hidden visibility for extension libraries whe
Author: Andres Freund <andres@anarazel.de>
2022-07-17 [8cf64d35e] Mark all symbols exported from extension libraries PGDLL
-->

<listitem>
<para>
Prevent extension libraries from exporting their symbols by default (Andres Freund, Tom Lane)
</para>

<para>
Functions that need to be called from the core backend or other extensions must now be explicitly marked <literal>PGDLLEXPORT</literal>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-07-07 [495ed0ef2] Make Windows 10 the minimal runtime requirement for WIN3
-->

<listitem>
<para>
Require <systemitem class="osname">Windows 10</systemitem> or newer versions (Michael Paquier, Juan José Santamaría Flecha)
</para>

<para>
Previously <systemitem class="osname">Windows Vista</systemitem> and <systemitem class="osname">Windows XP</systemitem> were supported.
</para>
</listitem>

<!--
Author: John Naylor <john.naylor@postgresql.org>
2022-09-14 [4c1532763] Bump minimum Perl version to 5.14
-->

<listitem>
<para>
Require <productname>Perl</productname> version 5.14 or later (John Naylor)
</para>
</listitem>

<!--
Author: John Naylor <john.naylor@postgresql.org>
2022-09-09 [b086a47a2] Bump minimum version of Bison to 2.3
-->

<listitem>
<para>
Require <productname>Bison</productname> version 2.3 or later (John Naylor)
</para>
</listitem>

<!--
Author: John Naylor <john.naylor@postgresql.org>
2022-09-09 [8b878bffa] Bump minimum version of Flex to 2.5.35
-->

<listitem>
<para>
Require <productname>Flex</productname> version 2.5.35 or later (John Naylor)
</para>
</listitem>

<!--
Author: Stephen Frost <sfrost@snowman.net>
2023-04-13 [f7431bca8] Explicitly require MIT Kerberos for GSSAPI
-->

<listitem>
<para>
Require <acronym>MIT</acronym> Kerberos for <acronym>GSSAPI</acronym> support (Stephen Frost)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-07-14 [6203583b7] Remove support for Visual Studio 2013
-->

<listitem>
<para>
Remove support for <productname>Visual Studio 2013</productname> (Michael Paquier)
</para>
</listitem>

<!--
Author: Thomas Munro <tmunro@postgresql.org>
2022-07-08 [9db300ce6] Remove HP-UX port.
-->

<listitem>
<para>
Remove support for <systemitem class="osname">HP-UX</systemitem> (Thomas Munro)
</para>
</listitem>

<!--
Author: Thomas Munro <tmunro@postgresql.org>
2022-07-08 [0ad5b48e5] Remove HP/Intel Itanium support.
-->

<listitem>
<para>
Remove support for <productname>HP/Intel Itanium</productname> (Thomas Munro)
</para>
</listitem>

<!--
Author: Thomas Munro <tmunro@postgresql.org>
2022-07-12 [718aa43a4] Further tidy-up for old CPU architectures.
Author: Thomas Munro <tmunro@postgresql.org>
2022-07-12 [14168d3c6] Doc: Acknowledge historically supported CPUs and OSes.
-->

<listitem>
<para>
Remove support for <productname>M68K</productname>, <productname>M88K</productname>, <productname>M32R</productname>, and <productname>SuperH</productname> <acronym>CPU</acronym> architectures (Thomas Munro)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-03-17 [98ae2c84a] libpq: Remove code for SCM credential authentication
-->

<listitem>
<para>
Remove <link linkend="libpq"><application>libpq</application></link> support for <acronym>SCM</acronym> credential authentication (Michael Paquier)
</para>

<para>
Backend support for this authentication method was removed in <productname>PostgresSQL</productname> 9.1.
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2022-09-21 [e6927270c] meson: Add initial version of meson based build system
-->

<listitem>
<para>
Add <link linkend="install-meson"><application>meson</application></link> build system (Andres Freund, Nazir Bilal Yavuz, Peter Eisentraut)
</para>

<para>
This eventually will replace the <productname>Autoconf</productname> and <systemitem class="osname">Windows</systemitem>-based <productname>MSVC</productname> build systems.
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2022-10-20 [c8e4030d1] Make finding openssl program a configure or meson option
-->

<listitem>
<para>
Allow control of the location of the <application>openssl</application> binary used by the build system (Peter Eisentraut)
</para>

<para>
Make finding <application>openssl</application> program a <application>configure</application> or <application>meson</application> option
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2022-12-07 [d3b111e32] Add option to specify segment size in blocks
-->

<listitem>
<para>
Add build option to allow testing of small <acronym>WAL</acronym> segment sizes (Andres Freund)
</para>

<para>
The build options are <link linkend="configure-option-with-segsize"><option>--with-segsize-blocks</option></link> and <option>-Dsegsize_blocks</option>.
</para>
</listitem>

<!--
Author: Andrew Dunstan <andrew@dunslane.net>
2023-01-23 [b90f0b574] Add non-destructive modes to pgindent
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-23 [62e1e28bf] Fix pgindent - -show-diff option.
Author: Andrew Dunstan <andrew@dunslane.net>
2023-01-24 [124937163] Improve exclude pattern file processing in pgindent
Author: Andrew Dunstan <andrew@dunslane.net>
2023-01-27 [a1c4cd6f2] Allow multiple - -excludes options in pgindent
Author: Andrew Dunstan <andrew@dunslane.net>
2023-02-08 [068a243b7] pgindent: more ways to find files to indent
Author: Andrew Dunstan <andrew@dunslane.net>
2023-02-12 [dab07e8c6] pgindent: filter files for the - -commit option
Author: Andrew Dunstan <andrew@dunslane.net>
2023-02-13 [b16259b3c] Remove obsolete pgindent options - -code-base and - -build
-->

<listitem>
<para>
Add <link linkend="source"><application>pgindent</application></link> options (Andrew Dunstan)
</para>

<para>
The new options are <option>--show-diff</option>, <option>--silent-diff</option>, <option>--commit</option>, and <option>--help</option>, and allow multiple <option>--exclude</option> options.  Also require the typedef file to be explicitly specified.  Options <option>--code-base</option> and <option>--build</option> were
also removed.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-02-12 [4e831f4ce] Import pg_bsd_indent sources.
-->

<listitem>
<para>
Add <link linkend="source"><application>pg_bsd_indent</application></link> source code to the main tree (Tom Lane)
</para>
</listitem>

<!--
Author: Tatsuo Ishii <ishii@postgresql.org>
2022-10-19 [d1e2a380c] Enhance make_ctags and make_etags.
-->

<listitem>
<para>
Improve <application>make_ctags</application> and <application>make_etags</application> (Yugo Nagata)
</para>
</listitem>

<!--
Author: Peter Eisentraut <peter@eisentraut.org>
2023-03-28 [90189eefc] Save a few bytes in pg_attribute
-->

<listitem>
<para>
Adjust <link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link> columns for efficiency (Peter Eisentraut)
</para>
</listitem>

    </itemizedlist>

   </sect3>

   <sect3 id="release-16-modules">
    <title>Additional Modules</title>

    <itemizedlist>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-09-02 [ff720a597] Fix planner to consider matches to boolean columns in ex
-->

<listitem>
<para>
Improve use of extension-based indexes on boolean columns (Zongliang Quan, Tom Lane)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-04-07 [a290378a3] Add support for Daitch-Mokotoff Soundex in contrib/fuzzy
-->

<listitem>
<para>
Add support for Daitch-Mokotoff Soundex to <link linkend="fuzzystrmatch"><application>fuzzystrmatch</application></link> (Dag Lem)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2022-07-06 [d4bfe4128] autho_explain: Add GUC to log query parameters
-->

<listitem>
<para>
Allow <link linkend="auto-explain"><application>auto_explain</application></link> to log values passed to parameterized statements (Dagfinn Ilmari Mannsåker)
</para>

<para>
This affects queries using server-side <link linkend="sql-prepare"><command>PREPARE</command></link>/<link linkend="sql-execute"><command>EXECUTE</command></link> and client-side parse/bind.  Logging is controlled by <link linkend="auto-explain-configuration-parameters-log-parameter-max-length"><literal>auto_explain.log_parameter_max_length</literal></link>;  by default query parameters will
be logged with no length restriction.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-01-26 [9d2d9728b] Make auto_explain print the query identifier in verbose 
-->

<listitem>
<para>
Have <link linkend="auto-explain"><application>auto_explain</application></link>'s <option>log_verbose</option> mode honor the value of <link linkend="guc-compute-query-id"><varname>compute_query_id</varname></link> (Atsushi Torikoshi)
</para>

<para>
Previously even if <varname>compute_query_id</varname> was enabled, <link linkend="auto-explain-configuration-parameters-log-verbose"><option>log_verbose</option></link> was not showing the query identifier.
</para>
</listitem>

<!--
Author: Andrew Dunstan <andrew@dunslane.net>
2023-01-06 [b1665bf01] Allow hyphens in ltree labels
-->

<listitem>
<para>
Change the maximum length of <link linkend="ltree"><application>ltree</application></link> labels from 256 to 1000 and allow hyphens (Garen Torikian)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-03-08 [daa8365a9] Reflect normalization of query strings for utilities in 
-->

<listitem>
<para>
Have <link linkend="pgstatstatements"><structname>pg_stat_statements</structname></link> normalize constants used in utility commands (Michael Paquier)
</para>

<para>
Previously constants appeared instead of placeholders, e.g., <literal>$1</literal>.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-01-23 [c31cf1c03] pg_walinspect: Add pg_get_wal_fpi_info()
Author: Michael Paquier <michael@paquier.xyz>
2023-03-10 [9ecb134a9] pg_walinspect: pg_get_wal_fpi_info() -> pg_get_wal_block
Author: Peter Geoghegan <pg@bowt.ie>
2023-03-30 [122376f02] Show record information in pg_get_wal_block_info.
Author: Peter Geoghegan <pg@bowt.ie>
2023-03-31 [df4f3ab51] Add show_data option to pg_get_wal_block_info.
-->

<listitem>
<para>
Add <link linkend="pgwalinspect"><application>pg_walinspect</application></link> function <link linkend="pgwalinspect-funcs-pg-get-wal-block-info"><function>pg_get_wal_block_info()</function></link> to report <acronym>WAL</acronym> block information (Michael Paquier, Melanie Plageman, Bharath Rupireddy)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-03-14 [5c1b66280] Rework design of functions in pg_walinspect
-->

<listitem>
<para>
Change how <link linkend="pgwalinspect"><application>pg_walinspect</application></link> functions <link linkend="pgwalinspect-funcs-pg-get-wal-records-info"><function>pg_get_wal_records_info()</function></link> and <link linkend="pgwalinspect-funcs-pg-get-wal-stats"><function>pg_get_wal_stats()</function></link> interpret ending <acronym>LSN</acronym>s (Bharath Rupireddy)
</para>

<para>
Previously ending <acronym>LSN</acronym>s which represent nonexistent <acronym>WAL</acronym> locations would generate an error, while they will now be interpreted as the end of the <acronym>WAL</acronym>.
</para>
</listitem>

<!--
Author: Peter Geoghegan <pg@bowt.ie>
2023-04-07 [7d8219a44] Show more detail in heapam rmgr descriptions.
Author: Peter Geoghegan <pg@bowt.ie>
2023-04-07 [1c453cfd8] Show more detail in nbtree rmgr descriptions.
Author: Peter Geoghegan <pg@bowt.ie>
2023-04-11 [96149a180] Fix Heap rmgr's desc output for infobits arrays.
Author: Peter Geoghegan <pg@bowt.ie>
2023-04-19 [50547a3fa] Fix wal_consistency_checking enhanced desc output.
-->

<listitem>
<para>
Add detailed descriptions of <acronym>WAL</acronym> records in <link linkend="pgwalinspect"><application>pg_walinspect</application></link> and <link linkend="pgwaldump"><application>pg_waldump</application></link> (Melanie Plageman, Peter Geoghegan)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-02 [1fd3dd204] Add bt_multi_page_stats() function to contrib/pageinspec
-->

<listitem>
<para>
Add <link linkend="pageinspect"><application>pageinspect</application></link> function <link linkend="pageinspect-b-tree-funcs"><function>bt_multi_page_stats()</function></link> to report statistics on multiple pages (Hamid Akhtar)
</para>

<para>
This is similar to <function>bt_page_stats()</function> except it can report on a range of pages.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-01-02 [1fd3dd204] Add bt_multi_page_stats() function to contrib/pageinspec
-->

<listitem>
<para>
Add empty range output column to <link linkend="pageinspect"><application>pageinspect</application></link> function <link linkend="pageinspect-brin-funcs"><function>brin_page_items()</function></link> (Tomas Vondra)
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-02-17 [35739b87d] Redesign archive modules
-->

<listitem>
<para>
Redesign archive modules to be more flexible (Nathan Bossart)
</para>

<para>
Initialization changes will require modules written for older versions of Postgres to be updated.
</para>
</listitem>

<!--
Author: Michael Paquier <michael@paquier.xyz>
2023-04-06 [1d477a907] Fix row tracking in pg_stat_statements with extended que
-->

<listitem>
<para>
Correct inaccurate <link linkend="pgstatstatements"><application>pg_stat_statements</application></link> row tracking extended query protocol statements (Sami Imseih)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-04-07 [f3fa31327] Add pg_buffercache_usage_counts() to contrib/pg_bufferca
-->

<listitem>
<para>
Add <link linkend="pgbuffercache"><application>pg_buffercache</application></link> function <function>pg_buffercache_usage_counts()</function> to report usage totals (Nathan Bossart)
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2022-10-13 [2589434ae] pg_buffercache: Add pg_buffercache_summary()
-->

<listitem>
<para>
Add <link linkend="pgbuffercache"><application>pg_buffercache</application></link> function <function>pg_buffercache_summary()</function> to report summarized buffer statistics (Melih Mutlu)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-20 [72a5b1fc8] Add @extschema:name@ and no_relocate options to extensio
-->

<listitem>
<para>
Allow the schemas of required extensions to be referenced in extension scripts using the new syntax <literal>@extschema:referenced_extension_name@</literal> (Regina Obe)
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2023-03-20 [72a5b1fc8] Add @extschema:name@ and no_relocate options to extensio
-->

<listitem>
<para>
Allow required extensions to be marked as non-relocatable using <link linkend="extend-extensions-files-no-relocate"><literal>no_relocate</literal></link> (Regina Obe)
</para>

<para>
This allows <literal>@extschema:referenced_extension_name@</literal> to be treated as a constant for the lifetime of the extension.
</para>
</listitem>

    </itemizedlist>

    <sect4 id="release-16-pgfdw">
     <title><link linkend="postgres-fdw"><application>postgres_fdw</application></link></title>

     <itemizedlist>

<!--
Author: Etsuro Fujita <efujita@postgresql.org>
2023-04-06 [983ec2300] postgres_fdw: Add support for parallel abort.
-->

<listitem>
<para>
Allow <application>postgres_fdw</application> to do aborts in parallel (Etsuro Fujita)
</para>

<para>
This is enabled with <application>postgres_fdw</application> option <link linkend="postgres-fdw-options-transaction-management"><option>parallel_abort</option></link>.
</para>
</listitem>

<!--
Author: Tomas Vondra <tomas.vondra@postgresql.org>
2022-12-30 [8ad51b5f4] Sample postgres_fdw tables remotely during ANALYZE
-->

<listitem>
<para>
Make <link linkend="sql-analyze"><command>ANALYZE</command></link> on foreign <application>postgres_fdw</application> tables more efficient (Tomas Vondra)
</para>

<para>
The <application>postgres_fdw</application> option <link linkend="postgres-fdw-options-cost-estimation"><option>analyze_sampling</option></link> controls the sampling method.
</para>
</listitem>

<!--
Author: Tom Lane <tgl@sss.pgh.pa.us>
2022-07-17 [31e5b5029] postgres_fdw: be more wary about shippability of reg* co
-->

<listitem>
<para>
Restrict shipment of <link linkend="datatype-oid"><type>reg</type></link>* type constants in <application>postgres_fdw</application> to those referencing built-in objects or extensions marked as shippable (Tom Lane)
</para>
</listitem>

<!--
Author: Andres Freund <andres@anarazel.de>
2023-01-23 [e4602483e] dblink, postgres_fdw: Handle interrupts during connectio
-->

<listitem>
<para>
Have <application>postgres_fdw</application> and <link linkend="dblink"><application>dblink</application></link> handle interrupts during connection establishment (Andres Freund)
</para>
</listitem>

     </itemizedlist>

    </sect4>

   </sect3>

  </sect2>

  <sect2 id="release-16-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>ADD HERE</member>
   </simplelist>
  </sect2>

 </sect1>