Re: bad estimates

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Ken Geis <kgeis(at)speakeasy(dot)org>
Cc: Bruno Wolff III <bruno(at)wolff(dot)to>, pgsql-performance(at)postgresql(dot)org
Subject: Re: bad estimates
Date: 2003-08-30 14:35:52
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Ken Geis <kgeis(at)speakeasy(dot)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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