Re: slow down on UPDATE using IN statements

Is the query below any different from what you are trying to accomplish.

 UPDATE requisicao SET conclusao='3' WHERE  now()-data>'15 days' ;

if you want to use the exact query more efficiently you may rewrite
using EXISTS as

UPDATE requisicao AS a SET conclusao='3' WHERE
EXISTS (select * from requisicao where reg=a.reg and
now()-data>'15  days' ) ;


Best Regards
Mallah.


> Hi there,
>
> I was in troubles with a UPDATE+IN statement:
>
> The following command use to take about 5 minutes to
> be done:
>
> UPDATE requisicao SET conclusao='3' WHERE reg IN
> (SELECT reg FROM requisicao WHERE now()-data>'15
> days');
>
> The table 'requisicao' has only about 400 lines (!!).
>
> If I change it to:
>
> UPDATE requisicao SET conclusao='3' WHERE reg IN (12,
> 45, 87, 98, 129, 350, 389);
>
> I have detected that the major problem isn't in the
> amount of lines changed, but in the subselect.
>
> How can I solve/optimize it? I would like to use the
> IN, but in the last case I would make a software
> change.
>
> Thanks in advance and
> Best regards,
>
> Marcelo Pereira
> Brazil
>
> Yahoo! Mail - o melhor webmail do Brasil
> http://mail.yahoo.com.br
>
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