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To: Michael Riess <mlriess@gmx.de>
cc: pgsql-performance@postgresql.org
Subject: Re: Autovacuum / full vacuum 
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Comments: In-reply-to Michael Riess <mlriess@gmx.de>
	message dated "Tue, 17 Jan 2006 15:33:18 +0100"
Date: Tue, 17 Jan 2006 10:36:11 -0500
Message-ID: <28618.1137512171@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Michael Riess <mlriess@gmx.de> writes:
> But actually I never understood why the database system slows down at 
> all when there is much unused space in the files.

Perhaps some of your common queries are doing sequential scans?  Those
would visit the empty pages as well as the full ones.

			regards, tom lane