Thanks Thomas for the response,
It means if I run VACUUM ANALYZE on pg_attribute or pg_class table, it is
completely safe? Can you please also please confirm what is meant by
"mid-level" vacuum?
Regards,
Inzamam Shafiq
Sr. DBA
From: Thomas Boussekey
Sent: Sunday, December 18, 2022 4:01 PM
To: Inzamam Shafiq
Cc: pgsql-general@lists.postgresql.org
Subject: Re: Autovacuum on sys tables
Hello Inzamam,
Le sam. 17 déc. 2022 à 08:16, Inzamam Shafiq
mailto:inzamam.sha...@hotmail.com>> a écrit :
Dear Experts,
Hope you are doing well.
I have a question that autovacuum is running on sys tables like pg_class,
pg_attribute, is it a normal thing? Further, what is dead tuples are not
removed from Autovacuum, can we remove the dead tuples using FULL VACUUMM or
pg_repack on sys tables?
pg_repack cannot run on system tables, it will FAIL with an explicit error
message explaining the limitation.
Each time you perform DDL operations (CREATE, DROP, ALTER), rows are
inserted/updated or deleted into the system tables : pg_class, pg_attribute ...
Autovacuum operations perform "low-level" operations, it can be interesting to
perform "middle-level" vacuum with VACUUM ANALYZE... that is not blocking, but
will be more a resource-consuming operation than autovacuum.
Performing VACUUM FULL operation will block access to these pillar tables of
your database.
If your application/users can handle it, go ahead!
At work on this kind of operation, I set a statement_timeout, in order to
properly stop the process if it is over a defined amount of time.
Hope this helps,
Thomas
Thank you.
Regards,
Inzamam Shafiq
Sr. DBA
