Date: Tue, 3 Sep 2002 08:37:27 +0000
From: tp <tp@emaze.net>
To: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: pgsql-sql@postgresql.org
Subject: Re: UPDATE & LIMIT together?
Message-ID: <20020903083727.GH5674@emaze.net>
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	<200208281701.g7SH1aI20777@candle.pha.pa.us>
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Hmm,,

thanks so far, it helped.

The query is horrible slow on full tables (>100.000 rows).
Is there any other solution? I just want to have the 'next 10 entries'
WHERE state=10 and update state=20.
(so that on the next request i or another process only gets the 
new entires in queue).


My query now looks like:
UPDATE queue SET state=20 WHERE (id) IN (SELECT id FROM queue LIMIT 10)


-tp

Bruce Momjian(pgman@candle.pha.pa.us)@Wed, Aug 28, 2002 at 01:01:36PM -0400:
> 
> You have to use a subquery returning the tables primary key to the
> UPDATE:
> 
> 	UPDATE tab SET x=1
> 	WHERE (primkey, col) IN (
> 		SELECT primkey,col FROM tab 
> 		ORDER BY col 
> 		LIMIT 10)
> 
> ---------------------------------------------------------------------------
> 
> tp wrote:
> -- Start of PGP signed section.
> > Hi
> > 
> > I want to SELECT at max. 10 rows and SET a variable for the
> > select 10 rows with the same query.
> > 
> > Under mysql i can use:
> > UPDATE table SET uniq_iq=12345 LIMIT 10
> > SELECT * FROM table WHERE uniq_id=1234;