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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ken Geis <kgeis@speakeasy.org>
Cc: Bruno Wolff III <bruno@wolff.to>
Cc: pgsql-performance@postgresql.org
Subject: Re: bad estimates
Date: Sat, 30 Aug 2003 10:35:52 -0400
Message-ID: <22271.1062254152@sss.pgh.pa.us> (raw)
In-Reply-To: <3F50308E.6070100@speakeasy.org>
References: <20030829025109.GD4373@wolff.to>
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	<20030829033818.GA5577@wolff.to>
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	<20030829040519.GA5746@wolff.to>
	<3F4ED1DC.50808@speakeasy.org>
	<20030829042453.GA5931@wolff.to>
	<3F4F0777.8090503@speakeasy.org>
	<20030830025503.GA30691@wolff.to>
	<3F50308E.6070100@speakeasy.org>

Ken Geis <kgeis@speakeasy.org> writes:
>  From what I've learned, we want to convince the optimizer to use a 
> table scan; that's a good thing.  I want it to use hashed aggregates, 
> but I can't convince it to (unless maybe I removed all of the 
> statistics.)

You probably just need to increase sort_mem.  Multiple aggregates take
more RAM to process in a hashtable style ...

			regards, tom lane

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