From: Bruno Wolff III <bruno@wolff.to>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: John A Meinel <john@arbash-meinel.com>
Cc: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: linux@alteeve.com
Cc: tobias@nordicbet.com
Cc: pgsql-performance@postgresql.org
Subject: Re: Index ot being used
Date: Mon, 13 Jun 2005 11:49:29 -0500
Message-ID: <20050613164929.GA12557@wolff.to> (raw)
In-Reply-To: <20542.1118679734@sss.pgh.pa.us>
References: <s2ad532e.099@gwmta.wicourts.gov>
<42AD9D8D.9060503@arbash-meinel.com>
<20050613154834.GA9203@wolff.to>
<20542.1118679734@sss.pgh.pa.us>
On Mon, Jun 13, 2005 at 12:22:14 -0400,
Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> I don't think the use-case has been shown that justifies doing this much
> work to ignore useless ORDER BY clauses. The examples that have come up
> in the past all suggest ignoring index columns not the other way 'round.
> Can you make a case that we need to do that part of it?
I don't think so. I don't think people are likely to order by constant
expressions except by adding them to the front to help optimization.
When I was thinking about this I was looking at what equivalences could
be used and didn't look back to see which ones would be useful in the
normal case. And I think it is a lot more likely people will leave out
columns they know not to be relevant than to include them.
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To: pgsql-performance@postgresql.org
Cc: bruno@wolff.to, tgl@sss.pgh.pa.us, john@arbash-meinel.com, Kevin.Grittner@wicourts.gov, linux@alteeve.com, tobias@nordicbet.com
Subject: Re: Index ot being used
In-Reply-To: <20050613164929.GA12557@wolff.to>
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