From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nikhil Shetty <nikhil.dba04@gmail.com>
cc: pgsql-admin@postgresql.org
Subject: Re: vacuumdb idle processes
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Comments: In-reply-to Nikhil Shetty <nikhil.dba04@gmail.com>
	message dated "Fri, 11 Jun 2021 23:28:23 +0530"
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Date: Fri, 11 Jun 2021 14:33:49 -0400
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Nikhil Shetty <nikhil.dba04@gmail.com> writes:
> I have done a setup to run vacuumdb with 8 parallel jobs daily. It has been
> running quite well.

Apparently not all that well, if it failed to keep us out of an
autovacuum-to-prevent-wraparound situation.  I suppose you had autovacuum
disabled because you thought this lashup was sufficient?

> Just today I saw there is an aggressive autovacuum process running(to
> prevent wraparound) on one of the table. vacuumdb which started later
> spawned the 8 connections. One connection (doing vacuum on the table on
> which an aggressive autovacuum is running) is waiting for "autovacuum(to
> prevent wraparound)" to complete while the other 7 connections are just
> sitting idle.

> I am okay that one connection is waiting since an aggressive autovacuum is
> running on that table but how come other connections have not released the
> sesion yet? Any reason for this?

Perhaps this is the last remaining table so vacuumdb has nothing
else for them to do.

			regards, tom lane