From: Alvaro Herrera <alvherre@commandprompt.com>
To: Josh Berkus <josh@agliodbs.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Rick <richard.branton@ca.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: autovacuum strategy / parameters
Date: Fri, 30 Apr 2010 23:08:20 -0400
Message-ID: <20100501030820.GI3151@alvh.no-ip.org> (raw)
In-Reply-To: <4BDB5ECE.4010607@agliodbs.com>
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<h2o603c8f071004271755v3e56a408hbd23b5c355058aa@mail.gmail.com>
<4BDB5ECE.4010607@agliodbs.com>
Josh Berkus escribió:
> #autovacuum_vacuum_scale_factor = 0.2
>
> This is set because in my experience, 20% bloat is about the level at
> which bloat starts affecting performance; thus, we want to vacuum at
> that level but not sooner. This does mean that very large tables which
> never have more than 10% updates/deletes don't get vacuumed at all until
> freeze_age; this is a *good thing*. VACUUM on large tables is expensive;
> you don't *want* to vacuum a billion-row table which has only 100,000
> updates.
Hmm, now that we have partial vacuum, perhaps we should revisit this.
> It would be worth doing a DBT2/DBT5 test run with different autovac
> settings post-8.4 so see if we should specifically change the vacuum
> threshold.
Right.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
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To: pgsql-performance@postgresql.org
Cc: alvherre@commandprompt.com, josh@agliodbs.com, robertmhaas@gmail.com, richard.branton@ca.com
Subject: Re: autovacuum strategy / parameters
In-Reply-To: <20100501030820.GI3151@alvh.no-ip.org>
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