Re: Pre-calculate hash join

From: Dimitri Fontaine <dfontaine(at)hi-media(dot)com>
To: warren(at)warrenandrachel(dot)com
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Pre-calculate hash join
Date: 2010-01-12 11:01:28
Message-ID: 87hbqra8on.fsf@hi-media-techno.com
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warren(at)warrenandrachel(dot)com writes:

> When joining two large tables [common in warehousing], a hash join is
> commonly selected. Calculating hash values for the merge phase is CPU
> intensive. Is there any way to pre-calculate value hashes to save that
> time? Would it even grant any performance to skip the build phase of
> the hash join?

Maybe maintaining a materialized view then using it in the queries would
be sufficient to solve your problem?

--
dim

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