From: Tom Lane <tgl@sss.pgh.pa.us>
To: Kris Jurka <books@ejurka.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: No hash join across partitioned tables?
Date: Fri, 17 Apr 2009 11:02:34 -0400
Message-ID: <21238.1239980554@sss.pgh.pa.us> (raw)
In-Reply-To: <Pine.BSO.4.64.0904162046050.27034@leary.csoft.net>
References: <Pine.BSO.4.64.0904161836540.11937@leary.csoft.net>
<7163.1239923531@sss.pgh.pa.us>
<Pine.BSO.4.64.0904161921080.11937@leary.csoft.net>
<Pine.BSO.4.64.0904162046050.27034@leary.csoft.net>
Kris Jurka <books@ejurka.com> writes:
> So the default disable_cost isn't enough to push it to use the hash join
> plan and goes back to nestloop. Since disable_cost hasn't been touched
> since January 2000, perhaps it's time to bump that up to match today's
> hardware and problem sizes?
I think disable_cost was originally set at a time when costs were
integers :-(. Yeah, there's probably no reason not to throw another
zero or two on it.
Is there another issue here besides that one? I think you were hoping
that the hash join would be faster than the alternatives, but the cost
estimate says it's a lot slower. Is that actually the case?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, books@ejurka.com
Subject: Re: No hash join across partitioned tables?
In-Reply-To: <21238.1239980554@sss.pgh.pa.us>
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