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

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Greg Sabino Mullane <greg@turnstep.com>, pgsql-hackers@postgresql.org
Date: 2009-12-03T03:53:36Z
Lists: pgsql-hackers
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