Allow some recovery parameters to be changed with reload (Peter Eisentraut)

These parameters are archive_cleanup_command, promote_trigger_file, recovery_end_command, and recovery_min_apply_delay.

Allow the streaming replication timeout (wal_sender_timeout) to be set per connection (Takayuki Tsunakawa)

Previously, this could only be set cluster-wide.

Add function pg_promote() to promote standbys to primaries (Laurenz Albe, Michaël Paquier)

Previously, this operation was only possible by using pg_ctl or creating a trigger file.

Allow replication slots to be copied (Masahiko Sawada)

The functions for this are pg_copy_physical_replication_slot() and pg_copy_logical_replication_slot().

Make max_wal_senders not count as part of max_connections (Alexander Kukushkin)

Add an explicit value of current for recovery_target_timeline (Peter Eisentraut)

Make recovery fail if a two-phase transaction status file is corrupt (Michaël Paquier)

Previously, a warning was logged and recovery continued, allowing the transaction to be lost.

Add REINDEX CONCURRENTLY option to allow reindexing without locking out writes (Michaël Paquier, Andreas Karlsson, Peter Eisentraut)

This is also controlled by the reindexdb application's --concurrently option.

Add support for generated columns (Peter Eisentraut)

The content of generated columns are computed from expressions (including references to other columns in the same table) rather than being specified by INSERT or UPDATE commands.

Add a WHERE clause to COPY FROM to control which rows are accepted (Surafel Temesgen)

This provides a simple way to filter incoming data.

Allow enumerated values to be added more flexibly (Andrew Dunstan, Tom Lane, Thomas Munro)

Previously, ALTER TYPE ... ADD VALUE could not be called in a transaction block, unless it was part of the same transaction that created the enumerated type. Now it can be called in a later transaction, so long as the new enumerated value is not referenced until after it is committed.

Add commands to end a transaction and start a new one (Peter Eisentraut)

The commands are COMMIT AND CHAIN and ROLLBACK AND CHAIN.

Add VACUUM and CREATE TABLE options to prevent VACUUM from truncating trailing empty pages (Takayuki Tsunakawa)

These options are vacuum_truncate and toast.vacuum_truncate. Use of these options reduces VACUUM's locking requirements, but prevents returning disk space to the operating system.

Allow VACUUM to skip index cleanup (Masahiko Sawada)

This change adds a VACUUM command option INDEX_CLEANUP as well as a table storage option vacuum_index_cleanup. Use of this option reduces the ability to reclaim space and can lead to index bloat, but it is helpful when the main goal is to freeze old tuples.

Add the ability to skip VACUUM and ANALYZE operations on tables that cannot be locked immediately (Nathan Bossart)

This option is called SKIP_LOCKED.

Allow VACUUM and ANALYZE to take optional Boolean argument specifications (Masahiko Sawada)

Prevent TRUNCATE, VACUUM and ANALYZE from requesting a lock on tables for which the user lacks permission (Michaël Paquier)

This prevents unauthorized locking, which could interfere with user queries.

Add EXPLAIN option SETTINGS to output non-default optimizer settings (Tomas Vondra)

This output can also be obtained when using auto_explain by setting auto_explain.log_settings.

Add OR REPLACE option to CREATE AGGREGATE (Andrew Gierth)

Allow modifications of system catalogs' options using ALTER TABLE (Peter Eisentraut)

Modifications of catalogs' reloptions and autovacuum settings are now supported. (Setting allow_system_table_mods is still required.)

Use all key columns' names when selecting default constraint names for foreign keys (Peter Eisentraut)

Previously, only the first column name was included in the constraint name, resulting in ambiguity for multi-column foreign keys.

Update assorted knowledge about Unicode to match Unicode 12.1.0 (Peter Eisentraut)

This fixes, for example, cases where psql would misformat output involving combining characters.

Update Snowball stemmer dictionaries with support for new languages (Arthur Zakirov)

This adds word stemming support for Arabic, Indonesian, Irish, Lithuanian, Nepali, and Tamil to full text search.

Allow creation of collations that report string equality for strings that are not bit-wise equal (Peter Eisentraut)

This feature supports “nondeterministic” collations that can define case- and accent-agnostic equality comparisons. Thus, for example, a case-insensitive uniqueness constraint on a text column can be made more easily than before. This is only supported for ICU collations.

Add support for ICU collation attributes on older ICU versions (Peter Eisentraut)

This allows customization of the collation rules in a consistent way across all ICU versions.

Allow data type name to more seamlessly be compared to other text types (Tom Lane)

Type name now behaves much like a domain over type text that has default collation “C”. This allows cross-type comparisons to be processed more efficiently.

Add support for the SQL/JSON path language (Nikita Glukhov, Teodor Sigaev, Alexander Korotkov, Oleg Bartunov, Liudmila Mantrova)

This allows execution of complex queries on JSON values using an SQL-standard language.

Add support for hyperbolic functions (Lætitia Avrot)

Also add log10() as an alias for log(), for standards compliance.

Improve the accuracy of statistical aggregates like variance() by using more precise algorithms (Dean Rasheed)

Allow date_trunc() to have an additional argument to control the time zone (Vik Fearing, Tom Lane)

This is faster and simpler than using the AT TIME ZONE clause.

Adjust to_timestamp()/to_date() functions to be more forgiving of template mismatches (Artur Zakirov, Alexander Korotkov, Liudmila Mantrova)

This new behavior more closely matches the Oracle functions of the same name.

Fix assorted bugs in XML functions (Pavel Stehule, Markus Winand, Chapman Flack)

Specifically, in XMLTABLE, xpath(), and xmlexists(), fix some cases where nothing was output for a node, or an unexpected error was thrown, or necessary escaping of XML special characters was omitted.

Allow the BY VALUE clause in XMLEXISTS and XMLTABLE (Chapman Flack)

This SQL-standard clause has no effect in PostgreSQL's implementation, but it was unnecessarily being rejected.

Prevent current_schema() and current_schemas() from being run by parallel workers, as they are not parallel-safe (Michaël Paquier)

Allow RECORD and RECORD[] to be used as column types in a query's column definition list for a table function that is declared to return RECORD (Elvis Pranskevichus)

Allow SQL commands and variables with the same names as those commands to be used in the same PL/pgSQL function (Tom Lane)

For example, allow a variable called comment to exist in a function that calls the COMMENT SQL command. Previously this combination caused a parse error.

Add new optional warning and error checks to PL/pgSQL (Pavel Stehule)

The new checks allow for run-time validation of INTO column counts and single-row results.

Add connection parameter tcp_user_timeout to control libpq's TCP timeout (Ryohei Nagaura)

Allow libpq (and thus psql) to report only the SQLSTATE value in error messages (Didier Gautheron)

Add libpq function PQresultMemorySize() to report the memory used by a query result (Lars Kanis, Tom Lane)

Remove the no-display/debug flag from libpq's options connection parameter (Peter Eisentraut)

This allows this parameter to be set by postgres_fdw.

Allow ecpg to create variables of data type bytea (Ryo Matsumura)

This allows ECPG clients to interact with bytea data directly, rather than using an encoded form.

Add PREPARE AS support to ECPG (Ryo Matsumura)

Allow vacuumdb to select tables for vacuum based on their wraparound horizon (Nathan Bossart)

The options are --min-xid-age and --min-mxid-age.

Allow vacuumdb to disable waiting for locks or skipping all-visible pages (Nathan Bossart)

The options are --skip-locked and --disable-page-skipping.

Add colorization to the output of command-line utilities (Peter Eisentraut)

This is enabled by setting the environment variable PG_COLOR to always or auto. The specific colors used can be adjusted by setting the environment variable PG_COLORS, using ANSI escape codes for colors. For example, the default behavior is equivalent to PG_COLORS="error=01;31:warning=01;35:locus=01".

Allow control of log file rotation via pg_ctl (Kyotaro Horiguchi, Alexander Kuzmenkov, Alexander Korotkov)

Previously, this was only possible via an SQL function or a process signal.

Properly detach the new server process during pg_ctl start (Paul Guo)

This prevents the server from being shut down if the shell script that invoked pg_ctl is interrupted later.

Allow pg_upgrade to use the file system's cloning feature, if there is one (Peter Eisentraut)

The --clone option has the advantages of --link, while preventing the old cluster from being changed after the new cluster has started.

Allow specification of the socket directory to use in pg_upgrade (Daniel Gustafsson)

This is controlled by --socketdir; the default is the current directory.

Allow pg_checksums to disable fsync operations (Michaël Paquier)

This is controlled by the --no-sync option.

Allow pg_rewind to disable fsync operations (Michaël Paquier)

Fix pg_test_fsync to report accurate open_datasync durations on Windows (Laurenz Albe)

Add CREATE ACCESS METHOD command to create new table types (Andres Freund, Haribabu Kommi, Álvaro Herrera, Alexander Korotkov, Dmitry Dolgov)

This enables the development of new table access methods, which can optimize storage for different use cases. The existing heap access method remains the default.

Add planner support function interfaces to improve optimizer estimates, inlining, and indexing for functions (Tom Lane)

This allows extensions to create planner support functions that can provide function-specific selectivity, cost, and row-count estimates that can depend on the function's arguments. Support functions can also supply simplified representations and index conditions, greatly expanding optimization possibilities.

Simplify renumbering manually-assigned OIDs, and establish a new project policy for management of such OIDs (John Naylor, Tom Lane)

Patches that manually assign OIDs for new built-in objects (such as new functions) should now randomly choose OIDs in the range 8000—9999. At the end of a development cycle, the OIDs used by committed patches will be renumbered down to lower numbers, currently somewhere in the 4xxx range, using the new renumber_oids.pl script. This approach should greatly reduce the odds of OID collisions between different in-process patches.

While there is no specific policy reserving any OIDs for external use, it is recommended that forks and other projects needing private manually-assigned OIDs use numbers in the high 7xxx range. This will avoid conflicts with recently-merged patches, and it should be a long time before the core project reaches that range.

Build Cygwin binaries using dynamic instead of static libraries (Marco Atzeri)

Remove configure switch --disable-strong-random (Michaël Paquier)

A strong random-number source is now required.

printf-family functions, as well as strerror and strerror_r, now behave uniformly across platforms within Postgres code (Tom Lane)

Notably, printf understands %m everywhere; on Windows, strerror copes with Winsock error codes (it used to do so in backend but not frontend code); and strerror_r always follows the GNU return convention.

Require a C99-compliant compiler, and MSVC 2013 or later on Windows (Andres Freund)

Use pandoc, not lynx, for generating plain-text documentation output files (Peter Eisentraut)

This affects only the INSTALL file generated during make dist and the seldom-used plain-text postgres.txt output file. Pandoc produces better output than lynx and avoids some locale/encoding issues. Pandoc version 1.13 or later is required.

Support use of images in the PostgreSQL documentation (Jürgen Purtz)

Allow ORDER BY sorts and LIMIT clauses to be pushed to postgres_fdw foreign servers in more cases (Etsuro Fujita)

Improve optimizer cost accounting for postgres_fdw queries (Etsuro Fujita)

Properly honor WITH CHECK OPTION on views that reference postgres_fdw tables (Etsuro Fujita)

While CHECK OPTIONs on postgres_fdw tables are ignored (because the reference is foreign), views on such tables are considered local, so this change enforces CHECK OPTIONs on them. Previously, only INSERTs and UPDATEs with RETURNING clauses that returned CHECK OPTION values were validated.

Allow pg_stat_statements_reset() to be more granular (Haribabu Kommi, Amit Kapila)

The function now allows reset of statistics for specific databases, users, and queries.

Allow control of the auto_explain log level (Tom Dunstan, Andrew Dunstan)

The default is LOG.

Update unaccent rules with new punctuation and symbols (Hugh Ranalli, Michaël Paquier)

Allow unaccent to handle some accents encoded as combining characters (Hugh Ranalli)

Allow unaccent to remove accents from Greek characters (Tasos Maschalidis)

Add a parameter to amcheck's bt_index_parent_check() function to check each index tuple from the root of the tree (Peter Geoghegan)

Improve oid2name and vacuumlo option handling to match other commands (Tatsuro Yamada)