Re: Using IN with subselect

From: Martijn van Oosterhout <kleptog(at)svana(dot)org>
To: Dave Smith <dave(dot)smith(at)candata(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Using IN with subselect
Date: 2004-11-25 17:11:12
Message-ID: 20041125171111.GB28393@svana.org
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Running EXPLAIN over the query will tell you...

On Thu, Nov 25, 2004 at 11:49:06AM -0500, Dave Smith wrote:
> I have a query with an in subquery like
>
> where x in (select x from y);
>
> Now the subquery is not related to the outer query so it always returns
> the same set. Is this subselect executed each time or just once? If it
> is executed each time, if I create a function would that then be only
> executed once?
>
> --
> Dave Smith
> CANdata Systems Ltd
> 416-493-9020
>
>
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--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.

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