Re: PATCH: postpone building buckets to the end of Hash (in HashJoin)

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: PATCH: postpone building buckets to the end of Hash (in HashJoin)
Date: 2015-12-17 21:28:41
Message-ID: 56732909.1070304@2ndquadrant.com
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Hi,

On 12/17/2015 07:20 PM, Robert Haas wrote:
...
>
> If this doesn't regress performance in the case where the number of
> buckets is estimated accurately to begin with, then I think this is
> a great idea. Can you supply some performance tests results for that
> case, and maybe some of the other cases also?

I don't see how it could regress performance, and the benchmarks I've
done confirm that. I'll do more thorough benchmarking and post the
results here, but not now as this patch is in 2016-01 CF and I want to
put all my time into reviewing patches from the open commitfest.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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