From: Bruno Wolff III <bruno@wolff.to>
To: T E Schmitz <mailreg@numerixtechnology.de>
Cc: Scott Marlowe <smarlowe@g2switchworks.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: cost of CREATE VIEW ... AS SELECT DISTINCT
Date: Tue, 29 Mar 2005 09:04:18 -0600
Message-ID: <20050329150418.GA32031@wolff.to> (raw)
In-Reply-To: <4249564B.1000807@numerixtechnology.de>
References: <42487A6D.6020506@numerixtechnology.de>
<1112047463.22988.25.camel@state.g2switchworks.com>
<424928D8.7060705@numerixtechnology.de>
<20050329132941.GA27251@wolff.to>
<4249564B.1000807@numerixtechnology.de>
On Tue, Mar 29, 2005 at 14:21:15 +0100,
T E Schmitz <mailreg@numerixtechnology.de> wrote:
>
> As far as I can see (via EXPLAIN), both DISTINCT and GROUP BY will lead
> to a sequentail scan. Is that correct?
If you need to read the whole table yes. However if you join the view
to something else that might not be necessary.
> If that's the case, I should come up with a different concept to obtain
> a list of ORIGINs.
That may be a good idea, especially if there are lots of rows for each
origin value.
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To: pgsql-sql@postgresql.org
Cc: bruno@wolff.to, mailreg@numerixtechnology.de, smarlowe@g2switchworks.com
Subject: Re: cost of CREATE VIEW ... AS SELECT DISTINCT
In-Reply-To: <20050329150418.GA32031@wolff.to>
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