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Hash Join Optimization

From: "Gokulakannan Somasundaram" <gokul007(at)gmail(dot)com>
To: "pgsql-hackers list" <pgsql-hackers(at)postgresql(dot)org>
Subject: Hash Join Optimization
Date: 2008-03-25 20:32:54
Message-ID: 9362e74e0803251332y43391419j2be7eec320b084b1@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Hi,
   I had a chance to go through the Hash join code of Postgresql and had the
following thoughts.

- Currently postgres takes the heaptuple from the slot and creates and
minimal_tuple and copies it into the temp file.

I think the creation of minimal_tuple in the middle is a overhead which can
be avoided by creating a mem-map and directly creating the minimal_tuple in
the mem-map. Since Hash join is used mainly to join huge tables, this might
benefit those warehouse customers of postgres.

Am i missing something???

Thanks,
Gokul.

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