Date: Fri, 23 Sep 2005 19:18:03 +0200
From: Stef <svb@ucs.co.za>
To: Bruno Wolff III <bruno@wolff.to>
Cc: Markus Benne <markus@m-bass.com>,
	pgsql-performance@postgresql.org
Subject: Re: VACUUM FULL vs CLUSTER
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In-Reply-To: <20050923165952.GA7327@wolff.to>
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Bruno Wolff III mentioned :
=> > => If you have a proper FSM setting you shouldn't need to do vacuum fulls
=> > => (unless you have an older version of postgres where index bloat might
=> > => be an issue).

Thanks Alvaro and Bruno

I just want to clarify something that I also couldn't 
find a clear cut answer for before. 

What is a proper fsm setting? 

Someone told me to set max_fsm_relations to the number of
relations in pg_class plus a few more to allow for new relations.
And max_fsm_pages to the number of rows in the biggest table I
want to vacuum, plus a few 1000's for extra room?

Where does this free space map sit? On the disk somewhere,
or in memory, or both.

I once set the max_fsm_pages very high by mistake, and postgres
then started up and used a _lot_ of shared memory, and I had to
increase shmmax. Is there abything to watch out for when bumping this
setting up a lot?

Kind Regards
Stefan