From: Jim C. Nasby <jim@nasby.net>
To: Tomas Vondra <tv@fuzzy.cz>
Cc: pgsql-performance@postgresql.org
Subject: Re: how to plan for vacuum?
Date: Thu, 25 Jan 2007 09:54:24 -0600
Message-ID: <20070125155424.GG64372@nasby.net> (raw)
In-Reply-To: <45B8602E.7000606@fuzzy.cz>
References: <45B6F0A8.1050705@oss.ntt.co.jp>
<20070125033917.GD64372@nasby.net>
<45B8602E.7000606@fuzzy.cz>
Please cc the list so others can reply as well...
On Thu, Jan 25, 2007 at 08:45:50AM +0100, Tomas Vondra wrote:
> > On Wed, Jan 24, 2007 at 02:37:44PM +0900, Galy Lee wrote:
> >> 1. How do we know if autovacuum is enough for my application, or should
> >> I setup a vacuum manually from cron for my application?
> >
> > Generally I trust autovac unless there's some tables where it's critical
> > that they be vacuumed frequently, such as a queue table or a web session
> > table.
>
> You can tune thresholds and scale factors for that particular table
> using pg_autovacuum. If you lower them appropriately, the vacuum will be
> fired more often for that table - but don't lower them too much, just go
> step by step until you reach values that are fine for you.
That doesn't work well if autovac gets tied up vacuuming a very large
table. Granted, when that happens there are considerations about the
long-running vacuum transaction (prior to 8.2), but in many systems
you'll still get some use out of other vacuums.
--
Jim C. Nasby, Database Architect jim@nasby.net
512.569.9461 (cell) http://jim.nasby.net
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To: pgsql-performance@postgresql.org
Cc: jim@nasby.net, tv@fuzzy.cz
Subject: Re: how to plan for vacuum?
In-Reply-To: <20070125155424.GG64372@nasby.net>
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