Message-ID: <4656E1B5.3020300@archonet.com>
Date: Fri, 25 May 2007 14:16:37 +0100
From: Richard Huxton <dev@archonet.com>
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To: Bastian Voigt <post@bastian-voigt.de>
Cc: pgsql-performance@postgresql.org
Subject: Re: My quick and dirty "solution" (Re: Performance Problem
	with Vacuum of bytea table (PG 8.0.13))
References: <46569E6A.2060509@bastian-voigt.de>
 <4656BB5E.3000109@archonet.com>
	<4656BEF1.4050609@bastian-voigt.de> <4656C1C7.3000003@archonet.com>
	<4656C411.8010509@bastian-voigt.de> <4656CDC2.6030106@archonet.com>
	<4656D6EC.5060506@bastian-voigt.de>
In-Reply-To: <4656D6EC.5060506@bastian-voigt.de>
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Bastian Voigt wrote:
> No, this did not help. The vacuum process is still running far too long 
> and makes everything slow. It is even worse than before, cause now the 
> system is slow almost all the time while when vacuuming only every 3 
> hours it is only slow once every three hours.....

Could you check the output of vacuum verbose on that table and see how 
much work it's doing? I'd have thought the actual bytea data would be 
TOASTed away to a separate table for storage, leaving the vacuum with 
very little work to do.

It might well be your actual problem is your disk I/O is constantly 
saturated and the vacuum just pushes it over the edge. In which case 
you'll either need more/better disks or to find a quiet time once a day 
to vacuum and just do so then.

-- 
   Richard Huxton
   Archonet Ltd