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Re: bad estimates

From: Ken Geis <kgeis(at)speakeasy(dot)org>
To: Bruno Wolff III <bruno(at)wolff(dot)to>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: bad estimates
Date: 2003-08-29 16:06:31
Message-ID: 3F4F7A07.30404@speakeasy.org (view raw or flat)
Thread:
Lists: pgsql-performance
Bruno Wolff III wrote:
> If you want both the max and the min, then things are going to be a bit
> more work. You are either going to want to do two separate selects
> or join two selects or use subselects. If there aren't enough prices
> per stock, the sequential scan might be fastest since you only need to
> go through the table once and don't have to hit the index blocks.
> 
> It is still odd that you didn't get a big speed up for just the min though.

I found I'm suffering from an effect detailed in a previous thread titled

	Does "correlation" mislead the optimizer on large tables?


Ken



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