Re: Improving planning of outer joins

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От Alvaro Herrera
Тема Re: Improving planning of outer joins
Дата
Msg-id 20051216202449.GD27602@surnet.cl
обсуждение исходный текст
Ответ на Re: Improving planning of outer joins  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Improving planning of outer joins  (Tom Lane <tgl@sss.pgh.pa.us>)
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Tom Lane wrote:
> Alvaro Herrera <alvherre@commandprompt.com> writes:
> > I wonder if the code is already able to transform right joins to left
> > joins, like
> >     (A rightjoin B on (Pab)) = (B leftjoin A on (Pab))
> 
> Yeah, we already know that part.  It's a freebie --- I didn't even
> bother mentioning rightjoin in my post, since it's equivalent to
> leftjoin after swapping the inputs.

Why the thing about the mergejoinable conditions then?  Is that even
true?

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support


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