Date: Mon, 15 Mar 2010 19:35:43 -0300
From: Alvaro Herrera <alvherre@commandprompt.com>
To: Scott Whitney <swhitney@journyx.com>
Cc: pgsql-admin@postgresql.org
Subject: Re: Autovac vs manual with analyze
Message-ID: <20100315223543.GH3323@alvh.no-ip.org>
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Scott Whitney wrote:

> So, my questions are: 
> 
> a) Is the manual vacuum needed for performance reasons, or is auto-vac sufficient? 
> b) How do my settings look? 
> c) Is there a way that the clogs get cleared via autovac, would a full vac of just template1/template0 (if that last is possible) do it? 
> 

Autovacuum should be sufficient, provided that the FSM settings are
large enough to hold 20% (plus a bit of slack) of your database total
size in dead tuples.  If they are not, your database starts to bloat and
you need ugly hacks like vacuum full to recover the dead space.

In 8.1, clog is only cleared by database-wide vacuums, which IIRC
autovac doesn't do unless it does a for-Xid-wraparound run, which is not
often.  Probably a weekly database-wide vacuum (not full, i.e. vacuumdb
without -f) is enough.

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