From: Tom Lane <tgl@sss.pgh.pa.us>
To: Rural Hunter <ruralhunter@gmail.com>
cc: pgsql-admin@postgresql.org
Subject: Re: Why auto vacuum almost running all the time on one toast table?
In-reply-to: <4FD6F4B3.8050509@gmail.com>
References: <4FD6F4B3.8050509@gmail.com>
Comments: In-reply-to Rural Hunter <ruralhunter@gmail.com>
	message dated "Tue, 12 Jun 2012 15:50:11 +0800"
Date: Tue, 12 Jun 2012 12:50:55 -0400
Message-ID: <18647.1339519855@sss.pgh.pa.us>

Rural Hunter <ruralhunter@gmail.com> writes:
> v9.1.3 on Ubuntu 10.04 server. I have one table which has frequent 
> insert and weekly deletion, no update. Recently, I found the auto vacuum 
> on the toast table of it almost running all the time. each run took 
> around 1 hour. I don't think there are so many inerts so that it reaches 
> the auto vacuum criteria(20%? changes). And there is no such frequent 
> auto vacuum on the main table. The last auto vacuum of the main table is 
> on 3rd Jun. what might cause this behavior?

Hm, is the autovacuum managing to complete, or is it getting kicked off
before it can complete?  It would help to see the messages those
CONTEXT lines are attached to; and/or you might check pg_stat_all_tables
to see when the last completed autovacuum was for both the main table
and its toast table.

			regards, tom lane