From: Masaru Sugawara <rk73@sea.plala.or.jp>
To: Alvar Freude <alvar@a-blast.org>
Cc: pgsql-sql@postgresql.org
Subject: Re: 2 Selects 1 is faster, why?
Date: Fri, 28 Jun 2002 00:04:07 +0900
Message-ID: <20020627234531.7ECB.RK73@sea.plala.or.jp> (raw)
In-Reply-To: <1371510000.1025105687@gnarzelwicht.delirium-arts.de>
References: <afag3c$kce$1@news.hub.org>
<1371510000.1025105687@gnarzelwicht.delirium-arts.de>
On Wed, 26 Jun 2002 17:34:47 +0200
Alvar Freude <alvar@a-blast.org> wrote:
> Hi,
>
> -- Eric <emayo@pozicom.net> wrote:
>
> > If I perform the following 2 selects, the first one is EXTREMELY slow
> > where the 2nd one is very fast.
>
> [...]
>
> > Why would 2 be so much faster? I have ran the EXPLAIN on this and index
> > scans are being used.
>
> I guess, the first query has to search for all ol.orderid the equivalent
> o.orderid; the second variant only has to search for '1234' in each
> ?.orderid, which is much faster.
You are right. And this type of optimising are not yet implemented.
Tom said it in the prior discussions.
Regards,
Masaru Sugawara
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To: pgsql-sql@postgresql.org
Cc: rk73@sea.plala.or.jp, alvar@a-blast.org
Subject: Re: 2 Selects 1 is faster, why?
In-Reply-To: <20020627234531.7ECB.RK73@sea.plala.or.jp>
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