Waiting for PostgreSQL 14 – Rename wal_keep_segments to wal_keep_size.

On 20th of July 2020, Fujii Masao committed patch:

Rename wal_keep_segments to wal_keep_size.
 
max_slot_wal_keep_size that was added in v13 and wal_keep_segments are
the GUC parameters to specify how much WAL files to retain for
the standby servers. While max_slot_wal_keep_size accepts the number of
bytes of WAL files, wal_keep_segments accepts the number of WAL files.
This difference of setting units between those similar parameters could
be confusing to users.
 
To alleviate this situation, this commit renames wal_keep_segments to
wal_keep_size, and make users specify the WAL size in it instead of
the number of WAL files.
 
There was also the idea to rename max_slot_wal_keep_size to
max_slot_wal_keep_segments, in the discussion. But we have been moving
away from measuring in segments, for example, checkpoint_segments was
replaced by max_wal_size. So we concluded to rename wal_keep_segments
to wal_keep_size.
 
Back-patch to v13 where max_slot_wal_keep_size was added.
 
Author: Fujii Masao
Reviewed-by: Álvaro Herrera, Kyotaro Horiguchi, David Steele
Discussion: https://postgr.es/m/574b4ea3-e0f9-b175-ead2-ebea7faea855@oss.nttdata.com

Continue reading Waiting for PostgreSQL 14 – Rename wal_keep_segments to wal_keep_size.

Waiting for PostgreSQL 13 – Add logical replication support to replicate into partitioned tables

On 6th of April 2020, Peter Eisentraut committed patch:

Add logical replication support to replicate into partitioned tables 
 
Mainly, this adds support code in logical/worker.c for applying
replicated operations whose target is a partitioned table to its
relevant partitions.
 
Author: Amit Langote <amitlangote09@gmail.com>
Reviewed-by: Rafia Sabih <rafia.pghackers@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Reviewed-by: Petr Jelinek <petr@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+HiwqH=Y85vRK3mOdjEkqFK+E=ST=eQiHdpj43L=_eJMOOznQ@mail.gmail.com

Continue reading Waiting for PostgreSQL 13 – Add logical replication support to replicate into partitioned tables

Waiting for PostgreSQL 13 – Add the option to report WAL usage in EXPLAIN and auto_explain.

On 6th of April 2020, Amit Kapila committed patch:

Add the option to report WAL usage in EXPLAIN and auto_explain.
 
This commit adds a new option WAL similar to existing option BUFFERS in the
EXPLAIN command.  This option allows to include information on WAL record
generation added by commit df3b181499 in EXPLAIN output.
 
This also allows the WAL usage information to be displayed via
the auto_explain module.  A new parameter auto_explain.log_wal controls
whether WAL usage statistics are printed when an execution plan is logged.
This parameter has no effect unless auto_explain.log_analyze is enabled.
 
Author: Julien Rouhaud
Reviewed-by: Dilip Kumar and Amit Kapila
Discussion: https://postgr.es/m/CAB-hujrP8ZfUkvL5OYETipQwA=e3n7oqHFU=4ZLxWS_Cza3kQQ@mail.gmail.com

Continue reading Waiting for PostgreSQL 13 – Add the option to report WAL usage in EXPLAIN and auto_explain.

Waiting for PostgreSQL 13 – Allow pg_stat_statements to track planning statistics.

On 2nd of April 2020, Fujii Masao committed patch:

Allow pg_stat_statements to track planning statistics.
 
This commit makes pg_stat_statements support new GUC
pg_stat_statements.track_planning. If this option is enabled,
pg_stat_statements tracks the planning statistics of the statements,
e.g., the number of times the statement was planned, the total time
spent planning the statement, etc. This feature is useful to check
the statements that it takes a long time to plan. Previously since
pg_stat_statements tracked only the execution statistics, we could
not use that for the purpose.
 
The planning and execution statistics are stored at the end of
each phase separately. So there are not always one-to-one relationship
between them. For example, if the statement is successfully planned
but fails in the execution phase, only its planning statistics are stored.
This may cause the users to be able to see different pg_stat_statements
results from the previous version. To avoid this,
pg_stat_statements.track_planning needs to be disabled.
 
This commit bumps the version of pg_stat_statements to 1.8
since it changes the definition of pg_stat_statements function.
 
Author: Julien Rouhaud, Pascal Legrand, Thomas Munro, Fujii Masao
Reviewed-by: Sergei Kornilov, Tomas Vondra, Yoshikazu Imai, Haribabu Kommi, Tom Lane
Discussion: https://postgr.es/m/CAHGQGwFx_=DO-Gu-MfPW3VQ4qC7TfVdH2zHmvZfrGv6fQ3D-Tw@mail.gmail.com
Discussion: https://postgr.es/m/CAEepm=0e59Y_6Q_YXYCTHZkqOc6H2pJ54C_Xe=VFu50Aqqp_sA@mail.gmail.com
Discussion: https://postgr.es/m/DB6PR0301MB21352F6210E3B11934B0DCC790B00@DB6PR0301MB2135.eurprd03.prod.outlook.com

Continue reading Waiting for PostgreSQL 13 – Allow pg_stat_statements to track planning statistics.

Waiting for PostgreSQL 13 – Enable BEFORE row-level triggers for partitioned tables

On 18th of March 2020, Alvaro Herrera committed patch:

Enable BEFORE row-level triggers for partitioned tables
 
... with the limitation that the tuple must remain in the same
partition.
 
Reviewed-by: Ashutosh Bapat
Discussion: https://postgr.es/m/20200227165158.GA2071@alvherre.pgsql

Continue reading Waiting for PostgreSQL 13 – Enable BEFORE row-level triggers for partitioned tables

Waiting for PostgreSQL 13 – Allow vacuum command to process indexes in parallel.

On 20th of January 2020, Amit Kapila committed patch:

Allow vacuum command to process indexes in parallel.
 
This feature allows the vacuum to leverage multiple CPUs in order to
process indexes.  This enables us to perform index vacuuming and index
cleanup with background workers.  This adds a PARALLEL option to VACUUM
command where the user can specify the number of workers that can be used
to perform the command which is limited by the number of indexes on a
table.  Specifying zero as a number of workers will disable parallelism.
This option can't be used with the FULL option.
 
Each index is processed by at most one vacuum process.  Therefore parallel
vacuum can be used when the table has at least two indexes.
 
The parallel degree is either specified by the user or determined based on
the number of indexes that the table has, and further limited by
max_parallel_maintenance_workers.  The index can participate in parallel
vacuum iff it's size is greater than min_parallel_index_scan_size.
 
Author: Masahiko Sawada and Amit Kapila
 
Mahendra Singh and Sergei Kornilov
 
Discussion:
https://postgr.es/m/CAD21AoDTPMgzSkV4E3SFo1CH_x50bf5PqZFQf4jmqjk-C03BWg@mail.gmail.com
https://postgr.es/m/CAA4eK1J-VoR9gzS5E75pcD-OH0mEyCdp8RihcwKrcuw7J-Q0+w@mail.gmail.com

Continue reading Waiting for PostgreSQL 13 – Allow vacuum command to process indexes in parallel.

Waiting for PostgreSQL 13 – ALTER TABLE … ALTER COLUMN … DROP EXPRESSION

Title: Waiting for PostgreSQL 13 – ALTER TABLE … ALTER COLUMN … DROP EXPRESSION

On 14th of January 2020, Peter Eisentraut committed patch:

ALTER TABLE ... ALTER COLUMN ... DROP EXPRESSION 
 
Add an ALTER TABLE subcommand for dropping the generated property from
a column, per SQL standard.
 
Discussion: https://www.postgresql.org/message-id/flat/-946e-0453-d841-%402ndquadrant.com

Continue reading Waiting for PostgreSQL 13 – ALTER TABLE … ALTER COLUMN … DROP EXPRESSION

Waiting for PostgreSQL 13 – Add support for –jobs in reindexdb

On 27th of July 2019, Michael Paquier committed patch:

Add support for --jobs in reindexdb
 
When doing a schema-level or a database-level operation, a list of
relations to build is created which gets processed in parallel using
multiple connections, based on the recent refactoring for parallel slots
in src/bin/scripts/.  System catalogs are processed first in a
serialized fashion to prevent deadlocks, followed by the rest done in
parallel.
 
This new option is not compatible with --system as reindexing system
catalogs in parallel can lead to deadlocks, and with --index as there is
no conflict handling for indexes rebuilt in parallel depending in the
same relation.
 
Author: Julien Rouhaud
 
Discussion: https://postgr.es/m/CAOBaU_YrnH_Jqo46NhaJ7uRBiWWEcS40VNRQxgFbqYo9kApUsg@mail.gmail.com

Continue reading Waiting for PostgreSQL 13 – Add support for –jobs in reindexdb

How to play with upcoming, unreleased, PostgreSQL?

Lately reader of my blog asked about some detail, and then in next comment said that he doesn't have PostgreSQL 12 (which is currently developed version of Pg) available.

Well, I answered the original question, but I figured that if someone is reading my Waiting for … series, then it would make sense that such person could play with devel Pg herself.

So, here is how to get it done.

Continue reading How to play with upcoming, unreleased, PostgreSQL?

Waiting for PostgreSQL 12 – Allow VACUUM to be run with index cleanup disabled.

On 4th of April 2019, Robert Haas committed patch:

Allow VACUUM to be run with index cleanup disabled.
 
 
This commit adds a new reloption, vacuum_index_cleanup, which
controls whether index cleanup is performed for a particular
relation by default.  It also adds a new option to the VACUUM
command, INDEX_CLEANUP, which can be used to override the
reloption.  If neither the reloption nor the VACUUM option is
used, the default is true, as before.
 
Masahiko Sawada, reviewed and tested by Nathan Bossart, Alvaro
Herrera, Kyotaro Horiguchi, Darafei Praliaskouski, and me.
The wording of the documentation is mostly due to me.
 
Discussion: http://postgr.es/m/CAD21AoAt5R3DNUZSjOoXDUY=naYPUOuffVsRzuTYMz29yLzQCA@mail.gmail.com

Continue reading Waiting for PostgreSQL 12 – Allow VACUUM to be run with index cleanup disabled.