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Re: Proposed patch to make mergejoin cost estimation more symmetric

From: Gregory Stark <stark(at)enterprisedb(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-patches(at)postgreSQL(dot)org>
Subject: Re: Proposed patch to make mergejoin cost estimation more symmetric
Date: 2007-12-07 09:15:54
Message-ID: 87bq92q305.fsf@oxford.xeocode.com (view raw or flat)
Thread:
Lists: pgsql-patches
"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> Any objections to applying the patch?

I like applying it.

You don't include any negative tests and corner cases as well; cases where the
new code shouldn't be disturbing the results such as a symmetric join or a
join against a single-row table. The comments make me think you ran them but
just didn't show them though.

What about a merge join against an empty table? I suppose there would just be
no statistics?


-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com
  Ask me about EnterpriseDB's 24x7 Postgres support!

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