Preserve the indisclustered setting of indexes rewritten by ALTER TABLE (Amit Langote, Justin Pryzby)

Previously, ALTER TABLE lost track of which index had been used for CLUSTER.

Preserve the replica identity properties of indexes rewritten by ALTER TABLE (Quan Zongliang, Peter Eisentraut)

Lock objects sooner during DROP OWNED BY (Álvaro Herrera)

This avoids failures in race-condition cases where another session is deleting some of the same objects.

Fix error-case processing for CREATE ROLE ... IN ROLE (Andrew Gierth)

Some error cases would be reported as “unexpected node type” or the like, instead of the intended message.

Ensure that members of the pg_read_all_stats role can read all statistics views, as expected (Magnus Hagander)

The functions underlying the pg_stat_progress_* views had not gotten this memo.

Fix full text search to handle NOT above a phrase search correctly (Tom Lane)

Queries such as !(foo<->bar) failed to find matching rows when implemented as a GiST or GIN index search.

Fix full text search for cases where a phrase search includes an item with both prefix matching and a weight restriction (Tom Lane)

Fix ts_headline() to make better headline selections when working with phrase queries (Tom Lane)

Fix bugs in gin_fuzzy_search_limit processing (Adé Heyward, Tom Lane)

A small value of gin_fuzzy_search_limit could result in unexpected slowness due to unintentionally rescanning the same index page many times. Another code path failed to apply the intended filtering at all, possibly returning too many values.

Allow input of type circle to accept the format “(x,y),r” as the documentation says it does (David Zhang)

Make the get_bit() and set_bit() functions cope with bytea strings longer than 256MB (Movead Li)

Since the bit number argument is only int4, it's impossible to use these functions to access bits beyond the first 256MB of a long bytea. We'll widen the argument to int8 in v13, but in the meantime, allow these functions to work on the initial substring of a long bytea.

Ignore file-not-found errors in pg_ls_waldir() and allied functions (Tom Lane)

This prevents a race condition failure if a file is removed between when we see its directory entry and when we attempt to stat() it.

Avoid possibly leaking an open-file descriptor for a directory in pg_ls_dir(), pg_timezone_names(), pg_tablespace_databases(), and allied functions (Justin Pryzby)

Fix polymorphic-function type resolution to correctly infer the actual type of an anyarray output when given only an anyrange input (Tom Lane)

Avoid unlikely crash when REINDEX is terminated by a session-shutdown signal (Tom Lane)

Fix low-probability crash after constraint violation errors in partitioned tables (Andres Freund)

Prevent printout of possibly-incorrect hash join table statistics in EXPLAIN (Konstantin Knizhnik, Tom Lane, Thomas Munro)

Fix reporting of elapsed time for heap truncation steps in VACUUM VERBOSE (Tatsuhito Kasahara)

Ensure that TimelineHistoryRead and TimelineHistoryWrite wait states are reported in all code paths that read or write timeline history files (Masahiro Ikeda)

Avoid possibly showing “waiting” twice in a process's PS status (Masahiko Sawada)

Avoid premature recycling of WAL segments during crash recovery (Jehan-Guillaume de Rorthais)

WAL segments that become ready to be archived during crash recovery were potentially recycled without being archived.

Avoid scanning irrelevant timelines during archive recovery (Kyotaro Horiguchi)

This can eliminate many attempts to fetch non-existent WAL files from archive storage, which is helpful if archive access is slow.

Remove bogus “subtransaction logged without previous top-level txn record” error check in logical decoding (Arseny Sher, Amit Kapila)

This condition is legitimately reachable in various scenarios, so remove the check.

Ensure that a replication slot's io_in_progress_lock is released in failure code paths (Pavan Deolasee)

This could result in a walsender later becoming stuck waiting for the lock.

Fix race conditions in synchronous standby management (Tom Lane)

During a change in the synchronous_standby_names setting, there was a window in which wrong decisions could be made about whether it is OK to release transactions that are waiting for synchronous commit. Another hazard for similarly wrong decisions existed if a walsender process exited and was immediately replaced by another.

Ensure nextXid can't go backwards on a standby server (Eka Palamadai)

This race condition could allow incorrect hot standby feedback messages to be sent back to the primary server, potentially allowing VACUUM to run too soon on the primary.

Add missing SQLSTATE values to a few error reports (Sawada Masahiko)

Fix PL/pgSQL to reliably refuse to execute an event trigger function as a plain function (Tom Lane)

Fix memory leak in libpq when using sslmode=verify-full (Roman Peshkurov)

Certificate verification during connection startup could leak some memory. This would become an issue if a client process opened many database connections during its lifetime.

Fix ecpg to treat an argument of just “-” as meaning “read from stdin” on all platforms (Tom Lane)

Allow tab-completion of the filename argument to psql's \gx command (Vik Fearing)

Add pg_dump support for ALTER ... DEPENDS ON EXTENSION (Álvaro Herrera)

pg_dump previously ignored dependencies added this way, causing them to be forgotten during dump/restore or pg_upgrade.

Fix pg_dump to dump comments on RLS policy objects (Tom Lane)

In pg_dump, postpone restore of event triggers till the end (Fabrízio de Royes Mello, Hamid Akhtar, Tom Lane)

This minimizes the risk that an event trigger could interfere with the restoration of other objects.

Fix quoting of --encoding, --lc-ctype and --lc-collate values in createdb utility (Michael Paquier)

contrib/lo's lo_manage() function crashed if called directly rather than as a trigger (Tom Lane)

In contrib/ltree, protect against overflow of ltree and lquery length fields (Nikita Glukhov)

Fix cache reference leak in contrib/sepgsql (Michael Luo)

Avoid failures when dealing with Unix-style locale names on Windows (Juan José Santamaría Flecha)

Use pkg-config, if available, to locate libxml2 during configure (Hugh McMaster, Tom Lane, Peter Eisentraut)

If pkg-config is not present or lacks knowledge of libxml2, we still query xml2-config as before.

This change could break build processes that try to make PostgreSQL use a non-default version of libxml2 by putting that version's xml2-config into the PATH. Instead, set XML2_CONFIG to point to the non-default xml2-config. That method will work with either older or newer PostgreSQL releases.

Include CFLAGS_SL in CXXFLAGS when building a shared library (Oleksii Kliukin)

This ensures that C++ source files are compiled correctly, for example by adding -fPIC when needed.

In MSVC builds, cope with spaces in the path name for Python (Victor Wagner)

In MSVC builds, fix detection of Visual Studio version to work with more language settings (Andrew Dunstan)

In MSVC builds, use -Wno-deprecated with bison versions newer than 3.0, as non-Windows builds already do (Andrew Dunstan)

Update time zone data files to tzdata release 2020a for DST law changes in Morocco and the Canadian Yukon, plus historical corrections for Shanghai.

The America/Godthab zone has been renamed to America/Nuuk to reflect current English usage; however, the old name remains available as a compatibility link.

Also, update initdb's list of known Windows time zone names to include recent additions, improving the odds that it will correctly translate the system time zone setting on that platform.