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

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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

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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

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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

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Waiting for PostgreSQL 12 – Add SETTINGS option to EXPLAIN, to print modified settings.

On 3rd of April 2019, Tomas Vondra committed patch:

Add SETTINGS option to EXPLAIN, to print modified settings.
 
 
Query planning is affected by a number of configuration options, and it
may be crucial to know which of those options were set to non-default
values.  With this patch you can say EXPLAIN (SETTINGS ON) to include
that information in the query plan.  Only options affecting planning,
with values different from the built-in default are printed.
 
This patch also adds auto_explain.log_settings option, providing the
same capability in auto_explain module.
 
Author: Tomas Vondra
 
Discussion: https://postgr.es/m/e1791b4c-df9c-be02-edc5-7c8874944be0@2ndquadrant.com

Continue reading Waiting for PostgreSQL 12 – Add SETTINGS option to EXPLAIN, to print modified settings.

Waiting for PostgreSQL 12 – Support foreign keys that reference partitioned tables

On 3rd of April 2019, Alvaro Herrera committed patch:

Support foreign keys that reference partitioned tables
 
 
Previously, while primary keys could be made on partitioned tables, it
was not possible to define foreign keys that reference those primary
keys.  Now it is possible to do that.
 
Author: Álvaro Herrera
 
Discussion: https://postgr.es/m/20181102234158.735b3fevta63msbj@alvherre.pgsql

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Waiting for PostgreSQL 12 – Log all statements from a sample of transactions

On 3rd of April 2019, Alvaro Herrera committed patch:

Log all statements from a sample of transactions
 
This is useful to obtain a view of the different transaction types in an
application, regardless of the durations of the statements each runs.
 
Author: Adrien Nayrat

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Waiting for PostgreSQL 12 – Report progress of CREATE INDEX operations

On 2nd of April 2019, Alvaro Herrera committed patch:

Report progress of CREATE INDEX operations
 
 
This uses the progress reporting infrastructure added by ,
adding support for CREATE INDEX and CREATE INDEX CONCURRENTLY.
 
There are two pieces to this: one is index-AM-agnostic, and the other is
AM-specific.  The latter is fairly elaborate for btrees, including
reportage for parallel index builds and the separate phases that btree
index creation uses; other index AMs, which are much simpler in their
building procedures, have simplistic reporting only, but that seems
sufficient, at least for non-concurrent builds.
 
The index-AM-agnostic part is fairly complete, providing insight into
the CONCURRENTLY wait phases as well as block-based progress during the
index validation table scan.  (The index validation index scan requires
patching each AM, which has not been included here.)
 
Reviewers: Rahila Syed, Pavan Deolasee, Tatsuro Yamada
Discussion: https://postgr.es/m/20181220220022.mg63bhk26zdpvmcj@alvherre.pgsql

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Waiting for PostgreSQL 12 – Generated columns

On 30th of March 2019, Peter Eisentraut committed patch:

Generated columns
 
This is an SQL-standard feature that allows creating columns that are
computed from expressions rather than assigned, similar to a view or
materialized view but on a column basis.
 
This implements one kind of generated column: stored (computed on
write).  Another kind, virtual (computed on read), is planned for the
future, and some room is left for it.
 
Discussion: https://www.postgresql.org/message-id/flat/-4019-bdb1-699e-@2ndquadrant.com

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