Re: IN optimization in 7.2 ?????

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: depesz(at)depesz(dot)pl
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: IN optimization in 7.2 ?????
Date: 2002-02-18 15:42:45
Message-ID: 200202181542.g1IFgjY21373@candle.pha.pa.us
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hubert depesz lubaczewski wrote:
> On Mon, Feb 18, 2002 at 09:52:19AM -0500, Bruce Momjian wrote:
> > Not that I know of.
>
> strange. what could lead to this results then?
> i used to think that IN (SELECT ...) is the slowest possible way at all.
>
> depesz
>
> p.s. of course both select's use indices, and table is vacuumed

I have always wondered this too. Seems IN evaluates the entire query
while EXISTS evaluates it for each row, or at least that is how I
understand it, so saying EXISTS is always faster may be wrong.
Comments?

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