Re: [HACKERS] subselect and optimizer

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От Boersenspielteam
Тема Re: [HACKERS] subselect and optimizer
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Msg-id 199804111020.MAA29029@mail.vocalweb.de
обсуждение исходный текст
Ответ на Re: [HACKERS] subselect and optimizer  (Bruce Momjian <maillist@candle.pha.pa.us>)
Ответы Re: [HACKERS] subselect and optimizer  (Bruce Momjian <maillist@candle.pha.pa.us>)
Список pgsql-hackers
> > 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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