Message-ID: <46796BF0.8010302@metacarta.com>
Date: Wed, 20 Jun 2007 14:03:28 -0400
From: Karl Wright <kwright@metacarta.com>
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To: Alvaro Herrera <alvherre@commandprompt.com>
Cc: Francisco Reyes <lists@stringsutils.com>,
	Tom Lane <tgl@sss.pgh.pa.us>, pgsql-performance@postgresql.org
Subject: Re: Performance query about large tables, lots of concurrent
 access
References: <14291.1182221811@sss.pgh.pa.us> <4677B831.8060704@metacarta.com>
	<4677D298.2010109@metacarta.com>
	<20070619132643.GC4265@alvh.no-ip.org>
	<4677DC06.3000300@metacarta.com>
	<20070619134637.GG4265@alvh.no-ip.org>
	<cone.1182267949.154012.90929.5001@35st.simplicato.com>
	<467963A8.2060703@metacarta.com>
	<20070620175300.GN30369@alvh.no-ip.org>
	<46796A08.8080601@metacarta.com>
	<20070620175758.GP30369@alvh.no-ip.org>
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Alvaro Herrera wrote:
> Karl Wright wrote:
>> Alvaro Herrera wrote:
>>> Karl Wright wrote:
>>>
>>>> (b) the performance of individual queries had already degraded 
>>>> significantly in the same manner as what I'd seen before.
>>> You didn't answer whether you had smaller, more frequently updated
>>> tables that need more vacuuming.  This comment makes me think you do.  I
>>> think what you should be looking at is whether you can forget vacuuming
>>> the whole database in one go, and make it more granular.
>> I am afraid that I did answer this.  My largest tables are the ones 
>> continually being updated.  The smaller ones are updated only infrequently.
> 
> Can you afford to vacuum them in parallel?
> 

Hmm, interesting question.  If VACUUM is disk limited then it wouldn't 
help, probably, unless I moved various tables to different disks 
somehow.  Let me think about whether that might be possible.

Karl