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From: Josh Berkus <josh@agliodbs.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Estimation issue with partitioned tables
Date: Sun, 07 Mar 2010 09:57:26 -0800
Message-ID: <4B93E906.5030804@agliodbs.com> (raw)
In-Reply-To: <603c8f071003031807p52f136edh683d19a1d5b46660@mail.gmail.com>
References: <4B8ACFE7.6040207@agliodbs.com>
	<603c8f071003030912k5750abadif64cb36d67ab99ae@mail.gmail.com>
	<4B8ED891.7060405@agliodbs.com>
	<603c8f071003031807p52f136edh683d19a1d5b46660@mail.gmail.com>

Robert,

>> Yeah, I can generate one pretty easily; the behavior is readily
>> observable and repeatable.  Will get on it RSN, but at you said, we're
>> not doing anything about it for 9.0.

Well, I can generate a test case, but on examination it turns out to be
nothing to do with partitioning; it's just good old "n-distinct
underestimation", and not really related to partitioning or joins.

--Josh Berkus

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