Month: January 2020

Which tables should be auto vacuumed or auto analyzed?

Recently I was in a situation where autovacuum couldn't keep up with changes. To solve the problem I finally decided to manually vacuum analyze all tables (manual vacuum/analyze is faster than one ran by autovacuum daemon).

But it irritated me that I didn't have ready way to check which tables are waiting for autovacuum to work on them.

So, I wrote it.

Continue reading Which tables should be auto vacuumed or auto analyzed?

Waiting for PostgreSQL 13 – Add functions gcd() and lcm() for integer and numeric types.

On 25th of January 2020, Dean Rasheed committed patch:

Add functions gcd() and lcm() for integer and numeric types.
 
These compute the greatest common divisor and least common multiple of
a pair of numbers using the Euclidean algorithm.
 
Vik Fearing, reviewed by Fabien Coelho.
 
Discussion: https://postgr.es/m/adbd3e0b-e3f1-5bbc-21db-03caf1cef0f7@2ndquadrant.com

Continue reading Waiting for PostgreSQL 13 – Add functions gcd() and lcm() for integer and numeric types.

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