E.4. Release 15

Improve planning time for queries referencing partitioned tables (David Rowley)

This change helps when only a few of many partitions are relevant.

Allow ordered scans of partitions to avoid sorting in more cases (David Rowley)

Previously, a partitioned table with a DEFAULT partition or a LIST partition containing multiple values could not be used for ordered partition scans. Now they can be used if such partitions are pruned during planning.

Improve foreign key behavior of updates on partitioned tables that move rows between partitions (Amit Langote)

Previously, such updates ran a delete action on the source partition and an insert action on the target partition. PostgreSQL will now run an update action on the partition root, providing cleaner semantics.

Allow CLUSTER on partitioned tables (Justin Pryzby)

Fix ALTER TRIGGER RENAME on partitioned tables to properly rename triggers on all partitions (Arne Roland, Álvaro Herrera)

Also prohibit cloned triggers from being renamed.

Allow btree indexes on system and TOAST tables to efficiently store duplicates (Peter Geoghegan)

Previously de-duplication was disabled for these types of indexes.

Improve lookup performance of GiST indexes that were built using sorting (Aliaksandr Kalenik, Sergei Shoulbakov, Andrey Borodin)

Allow unique constraints and indexes to treat NULL values as not distinct (Peter Eisentraut)

Previously NULL entries were always treated as distinct values, but this can now be changed by creating constraints and indexes using UNIQUE NULLS NOT DISTINCT .

Allow the ^@ starts-with operator and the starts_with() function to use btree indexes if using the C collation (Tom Lane)

Previously these could only use SP-GiST indexes.

Allow extended statistics to record statistics for a parent with all its children (Tomas Vondra, Justin Pryzby)

Regular statistics already tracked parent and parent-plus-all-children statistics separately.

Add server variable recursive_worktable_factor to allow the user to specify the expected size of the working table of a recursive query (Simon Riggs)

Allow hash lookup for NOT IN clauses with many constants (David Rowley, James Coleman)

Previously the code always sequentially scanned the list of values.

Allow SELECT DISTINCT to be parallelized (David Rowley)

Speed up encoding validation of UTF -8 text by processing 16 bytes at a time (John Naylor, Heikki Linnakangas)

This will improve text-heavy operations like COPY FROM .

Improve performance for sorts that exceed work_mem (Heikki Linnakangas)

When the sort data no longer fits in work_mem , switch to a batch sorting algorithm that uses more output streams than before.

Improve performance and reduce memory consumption of in-memory sorts (Ronan Dunklau, David Rowley, Thomas Munro, John Naylor)

Allow WAL full page writes to use LZ4 and Zstandard compression (Andrey Borodin, Justin Pryzby)

This is controlled by the wal_compression server setting.

Add support for writing WAL using direct I/O on macOS (Thomas Munro)

This only works if max_wal_senders = 0 and wal_level = minimal .

Allow vacuum to be more aggressive in setting the oldest frozen and multi transaction id (Peter Geoghegan)

Allow a query referencing multiple foreign tables to perform parallel foreign table scans in more cases (Andrey Lepikhov, Etsuro Fujita)

Improve the performance of window functions that use row_number() , rank() , dense_rank() and count() (David Rowley)

Improve the performance of spinlocks on high-core-count ARM64 systems (Geoffrey Blake)

Enable default logging of checkpoints and slow autovacuum operations (Bharath Rupireddy)

This changes the default of log_checkpoints to on and that of log_autovacuum_min_duration to 10 minutes. This will cause even an idle server to generate some log output, which might cause problems on resource-constrained servers without log file rotation. These defaults should be changed in such cases.

Generate progress messages in the server log during slow server starts (Nitin Jadhav, Robert Haas)

The messages report the cause of the delay. The time interval for notification is controlled by the new server variable log_startup_progress_interval .

Store cumulative statistics system data in shared memory (Kyotaro Horiguchi, Andres Freund, Melanie Plageman)

Previously this data was sent to a statistics collector process via UDP packets, and could only be read by sessions after transferring it via the file system. There is no longer a separate statistics collector process.

Add additional information to VACUUM VERBOSE and autovacuum logging messages (Peter Geoghegan)

Add EXPLAIN (BUFFERS) output for temporary file block I/O (Masahiko Sawada)

Allow log output in JSON format (Sehrope Sarkuni, Michael Paquier)

The new setting is log_destination = jsonlog .

Allow pg_stat_reset_single_table_counters() to reset the counters of relations shared across all databases (Sadhuprasad Patro)

Add wait events for local shell commands (Fujii Masao)

The new wait events are used when calling archive_command , archive_cleanup_command , restore_command and recovery_end_command .

Allow table accesses done by a view to optionally be controlled by privileges of the view's caller (Christoph Heiss)

Previously, view accesses were always treated as being done by the view's owner. That's still the default.

Allow members of the pg_write_server_files predefined role to perform server-side base backups (Dagfinn Ilmari Mannsåker)

Previously only superusers could perform such backups.

Allow GRANT to grant permissions to change individual server variables via SET and ALTER SYSTEM (Mark Dilger)

The new function has_parameter_privilege() reports on this privilege.

Add predefined role pg_checkpoint that allows members to run CHECKPOINT (Jeff Davis)

Previously checkpoints could only be run by superusers.

Allow members of the pg_read_all_stats predefined role to access the views pg_backend_memory_contexts and pg_shmem_allocations (Bharath Rupireddy)

Previously these views could only be accessed by superusers.

Allow GRANT to grant permissions on pg_log_backend_memory_contexts() (Jeff Davis)

Previously this function could only be run by superusers.

Add server variable shared_memory_size to report the size of allocated shared memory (Nathan Bossart)

Add server variable shared_memory_size_in_huge_pages to report the number of huge memory pages required (Nathan Bossart)

This is only supported on Linux.

Honor server variable shared_preload_libraries in single-user mode (Jeff Davis)

This change supports use of shared_preload_libraries to load custom access methods and WAL resource managers, which would be essential for database access even in single-user mode.

On Solaris, make the default setting of dynamic_shared_memory_type be sysv (Thomas Munro)

The previous default choice, posix , can result in spurious failures on this platform.

Allow postgres -C to properly report runtime-computed values (Nathan Bossart)

Previously runtime-computed values data_checksums , wal_segment_size , and data_directory_mode would report values that would not be accurate on the running server. However, this does not work on a running server.

Allow publication of all tables in a schema (Vignesh C, Hou Zhijie, Amit Kapila)

For example, this syntax is now supported: CREATE PUBLICATION pub1 FOR TABLES IN SCHEMA s1,s2 . ALTER PUBLICATION supports a similar syntax. Tables added later to the listed schemas will also be replicated.

Allow publication content to be filtered using a WHERE clause (Hou Zhijie, Euler Taveira, Peter Smith, Ajin Cherian, Tomas Vondra, Amit Kapila)

Rows not satisfying the WHERE clause are not published.

Allow publication content to be restricted to specific columns (Tomas Vondra, Álvaro Herrera, Rahila Syed)

Allow skipping of transactions on a subscriber using ALTER SUBSCRIPTION ... SKIP (Masahiko Sawada)

Add support for prepared (two-phase) transactions to logical replication (Peter Smith, Ajin Cherian, Amit Kapila, Nikhil Sontakke, Stas Kelvich)

The new CREATE_REPLICATION_SLOT option is called TWO_PHASE . pg_recvlogical now supports a new --two-phase option during slot creation.

Prevent logical replication of empty transactions (Ajin Cherian, Hou Zhijie, Euler Taveira)

Previously, publishers would send empty transactions to subscribers if subscribed tables were not modified.

Add SQL functions to monitor the directory contents of logical replication slots (Bharath Rupireddy)

The new functions are pg_ls_logicalsnapdir() , pg_ls_logicalmapdir() , and pg_ls_replslotdir() . They can be run by members of the predefined pg_monitor role.

Allow subscribers to stop the application of logical replication changes on error (Osumi Takamichi, Mark Dilger)

This is enabled with the subscriber option disable_on_error and avoids possible infinite error loops during stream application.

Adjust subscriber server variables to match the publisher so datetime and float8 values are interpreted consistently (Japin Li)

Some publishers might be relying on inconsistent behavior.

Add system view pg_stat_subscription_stats to report on subscriber activity (Masahiko Sawada)

The new function pg_stat_reset_subscription_stats() allows resetting these statistics counters.

Suppress duplicate entries in the pg_publication_tables system view (Hou Zhijie)

In some cases a partition could appear more than once.

Improve performance of psql 's \copy command, by sending data in larger chunks (Heikki Linnakangas)

Add \dconfig command to report server variables (Mark Dilger, Tom Lane)

This is similar to the server-side SHOW command, but it can process patterns to show multiple variables conveniently.

Add \getenv command to assign the value of an environment variable to a psql variable (Tom Lane)

Add + option to the \lo_list and \dl commands to show large-object privileges (Pavel Luzanov)

Add a pager option for the \watch command (Pavel Stehule, Thomas Munro)

This is only supported on Unix and is controlled by the PSQL_WATCH_PAGER environment variable.

Make psql include intra-query double-hyphen comments in queries sent to the server (Tom Lane, Greg Nancarrow)

Previously such comments were removed from the query before being sent. Double-hyphen comments that are before any query text are not sent, and are not recorded as separate psql history entries.

Adjust psql so that Readline 's meta- # command will insert a double-hyphen comment marker (Tom Lane)

Previously a pound marker was inserted, unless the user had taken the trouble to configure a non-default comment marker.

Make psql output all results when multiple queries are passed to the server at once (Fabien Coelho)

Previously, only the last query result was displayed. The old behavior can be restored by setting the SHOW_ALL_RESULTS psql variable to off .

After an error is detected in --single-transaction mode, change the final COMMIT command to ROLLBACK only if ON_ERROR_STOP is set (Michael Paquier)

Previously, detection of an error in a -c command or -f script file would lead to issuing ROLLBACK at the end, regardless of the value of ON_ERROR_STOP .

Improve psql 's tab completion (Shinya Kato, Dagfinn Ilmari Mannsåker, Peter Smith, Koyu Tanigawa, Ken Kato, David Fetter, Haiying Tang, Peter Eisentraut, Álvaro Herrera, Tom Lane, Masahiko Sawada)

Limit support of psql 's backslash commands to servers running PostgreSQL 9.2 or later (Tom Lane)

Remove code that was only used when running with an older server. Commands that do not require any version-specific adjustments compared to 9.2 will still work.

Make pg_dump dump public schema ownership changes and security labels (Noah Misch)

Improve performance of dumping databases with many objects (Tom Lane)

This will also improve the performance of pg_upgrade .

Improve parallel pg_dump 's performance for tables with large TOAST tables (Tom Lane)

Add dump/restore option --no-table-access-method to force restore to only use the default table access method (Justin Pryzby)

Limit support of pg_dump and pg_dumpall to servers running PostgreSQL 9.2 or later (Tom Lane)

Store pg_upgrade 's log and temporary files in a subdirectory of the new cluster called pg_upgrade_output.d (Justin Pryzby)

Previously such files were left in the current directory, requiring manual cleanup. Now they are automatically removed on successful completion of pg_upgrade .

Disable default status reporting during pg_upgrade operation if the output is not a terminal (Andres Freund)

The status reporting output can be enabled for non-tty usage by using --verbose .

Make pg_upgrade report all databases with invalid connection settings (Jeevan Ladhe)

Previously only the first database with an invalid connection setting was reported.

Make pg_upgrade preserve tablespace and database OIDs, as well as relation relfilenode numbers (Shruthi Gowda, Antonin Houska)

Add a --no-sync option to pg_upgrade (Michael Paquier)

This is recommended only for testing.

Limit support of pg_upgrade to old servers running PostgreSQL 9.2 or later (Tom Lane)

Allow pg_waldump output to be filtered by relation file node, block number, fork number, and full page images (David Christensen, Thomas Munro)

Make pg_waldump report statistics before an interrupted exit (Bharath Rupireddy)

For example, issuing a control-C in a terminal running pg_waldump --stats --follow will report the current statistics before exiting. This does not work on Windows.

Improve descriptions of some transaction WAL records reported by pg_waldump (Masahiko Sawada, Michael Paquier)

Allow pg_waldump to dump information about multiple resource managers (Heikki Linnakangas)

This is enabled by specifying the --rmgr option multiple times.

Allow postgres_fdw to push down CASE expressions (Alexander Pyhalov)

Add server variable postgres_fdw.application_name to control the application name of postgres_fdw connections (Hayato Kuroda)

Previously the remote session's application_name could only be set on the remote server or via a postgres_fdw connection specification. postgres_fdw.application_name supports some escape sequences for customization, making it easier to tell such connections apart on the remote server.

Allow parallel commit on postgres_fdw servers (Etsuro Fujita)

This is enabled with the CREATE SERVER option parallel_commit .