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From: Tomas Vondra <tv@fuzzy.cz>
Cc: pgsql-performance@postgresql.org
Subject: Re: PG8.2.1 choosing slow seqscan over idx scan
Date: Wed, 17 Jan 2007 20:14:36 +0100
Message-ID: <45AE759C.2000402@fuzzy.cz> (raw)
In-Reply-To: <1169044649.19974.1169715743@webmail.messagingengine.com>
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	<1169044649.19974.1169715743@webmail.messagingengine.com>

>> Assuming the table's NOT bloated, you may do well to increase the
>> effective_cache_size, which doesn't allocate anything, 
> <snip>
>> try setting it to something like 512MB or so.
> 
> It's currently set to 1000MB.
> 
> 
>> If your table is bloating, and you don't have idle transactions hanging
>> of the database, it could be that your fsm settings are too low.
> 
> fsm is currently set to 2000000.  Is there any harm in setting it too
> high? =)

I generally recomend to use this - it's a nice list of the most
important settings in postgresql.conf (with respect to performance),
along with a short explanation, and suggested values:

   http://www.powerpostgresql.com/PerfList

I'm using it as a general guide when setting and tuning our servers.

Anyway, as someone already pointed out, it's an art to choose the proper
values - there's nothing like 'the only best values'.

tomas



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