Re: Re: [COMMITTERS] pgsql: Rewrite GEQO's gimme_tree function so that it always finds a - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Re: [COMMITTERS] pgsql: Rewrite GEQO's gimme_tree function so that it always finds a
Date
Msg-id 29192.1259812416@sss.pgh.pa.us
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In response to Re: Re: [COMMITTERS] pgsql: Rewrite GEQO's gimme_tree function so that it always finds a  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: Re: [COMMITTERS] pgsql: Rewrite GEQO's gimme_tree function so that it always finds a  (Robert Haas <robertmhaas@gmail.com>)
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Robert Haas <robertmhaas@gmail.com> writes:
> Well, when I was testing, I believe I observed that an n-way join with
> 1 cross join was slower to plan than an n-way join with no cross
> joins.  ISTM that it should actually be faster, because you should
> plan it like an (n-1)-way join and then do the cross join at the end.

It's not entirely clear to me what case you're describing, but I wonder
whether this was a "flat" join problem or restricted by the collapse
limits.
        regards, tom lane


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