From: Ken Geis <kgeis@speakeasy.org>
To: Bruno Wolff III <bruno@wolff.to>
Cc: pgsql-performance@postgresql.org
Subject: Re: bad estimates
Date: Fri, 29 Aug 2003 09:06:31 -0700
Message-ID: <3F4F7A07.30404@speakeasy.org> (raw)
In-Reply-To: <20030829040519.GA5746@wolff.to>
References: <3F4E99F7.7080604@speakeasy.org>
<20030829025109.GD4373@wolff.to>
<3F4EBF7E.8020602@speakeasy.org>
<20030829030156.GF4373@wolff.to>
<3F4EC1D0.5010503@speakeasy.org>
<20030829033818.GA5577@wolff.to>
<3F4ECC78.7090502@speakeasy.org>
<20030829040519.GA5746@wolff.to>
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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To: pgsql-performance@postgresql.org
Cc: kgeis@speakeasy.org, bruno@wolff.to
Subject: Re: bad estimates
In-Reply-To: <3F4F7A07.30404@speakeasy.org>
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