Date: Thu, 11 Jan 2007 00:10:34 -0300
From: Alvaro Herrera <alvherre@commandprompt.com>
To: "Jim C. Nasby" <jim@nasby.net>
Cc: Jeremy Haile <jhaile@fastmail.fm>, pgsql-performance@postgresql.org
Subject: Re: High inserts, bulk deletes - autovacuum vs scheduled vacuum
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	Jeremy Haile <jhaile@fastmail.fm>, pgsql-performance@postgresql.org
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Jim C. Nasby wrote:

> > Is the best way to do that usually to lower the scale factors?  Is it
> > ever a good approach to lower the scale factor to zero and just set the
> > thresholds to a pure number of rows? (when setting it for a specific
> > table)
> 
> The problem is what happens if autovac goes off and starts vacuuming
> some large table? While that's going on your queue table is sitting
> there bloating. If you have a separate cronjob to handle the queue
> table, it'll stay small, especially in 8.2.

You mean "at least in 8.2".  In previous releases, you could vacuum
that queue table until you were blue on the face, but it would achieve
nothing because it would consider that the dead tuples were visible to a
running transaction: that running the vacuum on the large table.  This
is an annoyance that was fixed in 8.2.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.