Re: execution plan is wrong, or the query ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alex Burkoff <alex(dot)burkoff(at)jivesoftware(dot)com>
Cc: "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Subject: Re: execution plan is wrong, or the query ?
Date: 2012-12-11 17:10:42
Message-ID: 17815.1355245842@sss.pgh.pa.us
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Alex Burkoff <alex(dot)burkoff(at)jivesoftware(dot)com> writes:
> I think I am just looking for an opinion on fundamentals. Can WHERE clause impact an OUTER JOIN ?

Sure. I noticed for instance that your query had some outer joins that
were simplified to plain joins as a result of strict WHERE clauses above
them. That's not incorrect.

> What I am seeing is that on 9.2 rows from the joined table are restricted prior to joining them with the rest
> of the tables, and that leads to incorrect results. I have noticed such behaviour only when CASE is used
> in the WHERE clause - straight text comparison does produce correct results.

Oh? Hm, I wonder whether you are needing this fix:
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=72a4231f0c80f213a4fa75356dc3c6b7c7419059
Although that bug exists in some form back to 7.4, 9.2 had a more
obvious form of the disease, which is what led to its diagnosis.
If you're not running 9.2.2, give that a try and see if it's better.

regards, tom lane

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