From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Kris Jurka <books(at)ejurka(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: No hash join across partitioned tables? |
Date: | 2009-04-17 15:02:34 |
Message-ID: | 21238.1239980554@sss.pgh.pa.us |
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Lists: | pgsql-hackers pgsql-performance |
Kris Jurka <books(at)ejurka(dot)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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