From: | Oleg Bartunov <oleg(at)sai(dot)msu(dot)su> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Strange query plan |
Date: | 2001-06-05 15:02:00 |
Message-ID: | Pine.GSO.4.33.0106051756490.26250-100000@ra.sai.msu.su |
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Lists: | pgsql-hackers |
On Tue, 5 Jun 2001, Tom Lane wrote:
> Oleg Bartunov <oleg(at)sai(dot)msu(dot)su> writes:
> > should be
> > select msg_prt.tid as mid from msg_prt
> > where exists (select idx.tid from idx where msg_prt.tid=idx.tid
> > and idx.did=1 and ( idx.lid = 1207 or idx.lid=59587 ));
> > but this is not a big win.
>
> Shouldn't be any win at all: the IN expression-list notation will get
> translated to exactly that form.
Sure
>
> > Anyway, what's about original query ?
>
> IN/EXISTS subqueries suck. This has been true for a long time and is
> going to be true for a while longer, unless someone else fixes it before
> I have a chance to look at it. See if you can't rewrite your query as
> a plain join.
>
That's why we've moved to GiST and feel fine :-) That query we used in
our old project, now swithing to GiST.
> regards, tom lane
>
Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83
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