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From: "Josh Berkus" <josh@agliodbs.com>
Subject: Re: Performance of request of type WHERE ... IN ( ... )
To: Achilleus Mantzios <achill@matrix.gatewaynet.com>,
	Th Templ <templ_th@hotmail.com>
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Th,

> > I have performance problem of an request of type ... WHERE ... IN (
> ... ).
> > How to improve performance of this type of request when a group of
> id in the
> > 'in' is important.
> 
> Try WHERE ... EXISTS (...).

The explanation of the difference btw. IN and EXISTS is in the
PostgreSQL FAQ on the web site.

-Josh