Re: [HACKERS] subselect and optimizer

From: "Boersenspielteam" <boersenspiel(at)vocalweb(dot)de>
To: Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>
Cc: hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] subselect and optimizer
Date: 1998-04-11 12:27:01
Message-ID: 199804111020.MAA29029@mail.vocalweb.de
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> > But this patch still didn't help for a simple join without a where
> > clause. The query plan says it uses two sequential scans, where 6.2.1
> > uses two index scans.
>
> But we didn't have subselcts in 6.2.1?

No, but in the more general case of a simple join over two tables
with fields with an index declared on them.

say: Select * from Trans, Spieler where
Spieler.spieler_nr=Trans.spieler_nr

Uses indices in 6.2.1, doesn't use them in 6.3.1 (two seq scans).

I just wanted to remind you, that these problems are not restricted
to subqueries, but seem to be a more general 'flaw' in 6.3.x .

Hope this helps.

Ulrich

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