From: | Felipe Schnack <felipes(at)ritterdosreis(dot)br> |
---|---|
To: | Holger Klawitter <lists(at)klawitter(dot)de>, pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: LIMIT clause optimization |
Date: | 2003-01-07 12:44:15 |
Message-ID: | 1041943455.6409.39.camel@desenv1.ritterdosreis.br |
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Thread: | |
Lists: | pgsql-general |
Why? I don't understand. If I create a query and want just the first
row from it, wouldn't speed up things a lot just adding "LIMIT 1" in the
end of the query?
On Tue, 2003-01-07 at 10:44, Holger Klawitter wrote:
> Am Dienstag, 7. Januar 2003 12:47 schrieb Felipe Schnack:
> > I was wondering... (a newbie starting to understand how to optimize
> > queries)
> > In which step of query execution the LIMIT clause is executed? I mean
> > I have a query that would return, let's say, 6 rows, but I add a "LIMIT
> > 1" in the end of it.
> > I would speed up things because I would have less data fetching from
> > the database, right?
>
> Limit kicks in quite late as it has to be done after sorting. And it is not
> recommended to use LIMIT without ORDER BY.
>
> With kind regards / mit freundlichem Gruß
> Holger Klawitter
> --
> Holger Klawitter http://www.klawitter.de
> lists(at)klawitter(dot)de
--
Felipe Schnack
Analista de Sistemas
felipes(at)ritterdosreis(dot)br
Cel.: (51)91287530
Linux Counter #281893
Centro Universitário Ritter dos Reis
http://www.ritterdosreis.br
ritter(at)ritterdosreis(dot)br
Fone/Fax.: (51)32303341
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