From: Shaun Thomas <sthomas@optionshouse.com>
To: Thomas Kellerer <spam_eater@gmx.net>
Cc: pgsql-performance@postgresql.org
Subject: Re: Thinking About Correlated Columns (again)
Date: Thu, 16 May 2013 07:47:08 -0500
Message-ID: <5194D54C.6030901@optionshouse.com> (raw)
In-Reply-To: <kn0r9o$5je$1@ger.gmane.org>
References: <5193AA62.2040700@optionshouse.com>
<kn0r9o$5je$1@ger.gmane.org>
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On 05/15/2013 03:31 PM, Thomas Kellerer wrote:
> What happens if you create one index for each column? (instead of one
> combined index)
I just created the combined index to simplify the output. With two
indexes, it does the usual bitmap index scan. Even then the row estimate
is off by a factor of 1000, which is the actual problem.
The other reason I tried the combined index was that there was some
noise a while back about having the planner check for possible column
correlations on composite indexes. Clearly that ended up not being the
case, but it was worth examination.
--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604
312-676-8870
sthomas@optionshouse.com
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To: pgsql-performance@postgresql.org
Cc: sthomas@optionshouse.com, spam_eater@gmx.net
Subject: Re: Thinking About Correlated Columns (again)
In-Reply-To: <5194D54C.6030901@optionshouse.com>
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