Re: Using the IN clauise

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Тема Re: Using the IN clauise
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Msg-id 000801c27c55$ed66d900$2766f30a@development.greatgulfhomes.com
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Ответы Re: Using the IN clauise  (Robert Treat <xzilla@users.sourceforge.net>)
Список pgsql-general
My post didn't go through the first time, so here goes again:
>
>
> I thought I read somewhere that it was better to avoid using
> the IN clause (at least when that means doing a subselect)
> for efficiency reasons, but I cannot find it on the website now.
>
> Does anyone know where that is?
>
> And can someone confirm the following:
>
> This:
> SELECT t1.f1
> FROM t1
> WHERE t1.f1 IN (select f1 from t2 AS t2 where t2.f1 = t1.f1
> AND t2.f2 = 'v1')
>
> is generally slower to run then:
> SELECT t1.f1
> FROM t1, t2
> WHERE t1.f1 = t2.f1
>   AND t2.f3 = 'v1'
>
> Thanks
>
> Terry Fielder
> Network Engineer
> Great Gulf Homes / Ashton Woods Homes
> terry@greatgulfhomes.com
>
>

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