Message-ID: <4D4C478D.9070909@2ndquadrant.com>
Date: Fri, 04 Feb 2011 13:38:05 -0500
From: Greg Smith <greg@2ndquadrant.com>
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To: felix <crucialfelix@gmail.com>
CC: sthomas@peak6.com, pgsql-performance@postgresql.org
Subject: Re: Really really slow select count(*)
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felix wrote:
> and do you agree that I should turn CLUSTER ON ?
> I have no problem to stop all tasks to this table at night and just 
> reload it

You don't turn it on; it's a one time operation that does a cleanup.  It 
is by far the easiest way to clean up the mess you have right now.  
Moving forward, if you have max_fsm_pages set to an appropriate number, 
you shouldn't end up back in this position again.  But VACUUM along 
won't get you out of there, and VACUUM FULL is always a worse way to 
clean this up than CLUSTER.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books