From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jim Nasby <jnasby@enova.com>
cc: Merlin Moncure <mmoncure@gmail.com>,
 "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Problems with hash join over nested loop
In-reply-to: <526FE086.4020903@enova.com>
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Comments: In-reply-to Jim Nasby <jnasby@enova.com>
 message dated "Tue, 29 Oct 2013 11:21:26 -0500"
Date: Tue, 29 Oct 2013 12:45:14 -0400
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Jim Nasby <jnasby@enova.com> writes:
> I'm also wondering if it's time to raise those limits.

Yeah, possibly.  The current default values were set on machines much
smaller/slower than most current hardware.

I think also that the collapse limits were invented mainly to keep people
out of GEQO's clutches, but we've made some significant fixes in GEQO
since then.  Maybe the real answer is to make the default collapse limits
much higher, and lower geqo_threshold to whatever we think the threshold
of pain is for applying the regular planner.

			regards, tom lane


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