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Message-ID: <46F7D2C7.70105@enterprisedb.com>
Date: Mon, 24 Sep 2007 16:07:51 +0100
From: "Heikki Linnakangas" <heikki@enterprisedb.com>
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To: =?iso-8859-1?Q?G=E1bor_Farkas?= <gabor@nekomancer.net>
Cc: <pgsql-performance@postgresql.org>
Subject: Re: select count(*) performance (vacuum did not help)
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	<46F7D207.3000901@nekomancer.net>
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Gábor Farkas wrote:
> hmm... can a full-vacuum be performed while the database is still "live"
> (i mean serving requests)?
> 
> will the db still be able to respond to queries?

VACUUM FULL will exclusive lock the table, which means that other
queries accessing it will block and wait until it's finished.

> or in a different way:
> 
> if i do a full vacuum to that table only, will the database still serve
> data from the other tables at a normal speed?

Yes. The extra I/O load vacuum full generates while it's running might
disrupt other activity, though.

-- 
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com