From: eggyknap <eggyknap@gmail.com>
To: Nikolas Everett <nik9000@gmail.com>
Cc: Heikki Linnakangas <hlinnakangas@vmware.com>
Cc: sthomas@optionshouse.com, "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Thinking About Correlated Columns (again)
Date: Wed, 15 May 2013 13:23:25 -0600
Message-ID: <5193e08b.8271440a.1813.1075@mx.google.com> (raw)
In-Reply-To: <CAPmjWd08=Pk2+fSGeg61iAKY03YUySC1Ce5tpA-hGBZn59=3Aw@mail.gmail.com>
References: <5193AA62.2040700@optionshouse.com>
<5193AF36.3040409@vmware.com>
<CAPmjWd08=Pk2+fSGeg61iAKY03YUySC1Ce5tpA-hGBZn59=3Aw@mail.gmail.com>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-performance>
On Wed, May 15, 2013 at 01:30:57PM -0400, Nikolas Everett wrote:
> The option that always made the most sense to me was having folks ask
> postgres to collect the statistic by running some command that marks two
> columns as correlated. This could at least be a starting point.
One suggestion made in the past was to calculate these stats (provided someone
comes up with something worthwhile to calculate, that is) for all columns
involved in a multicolumn index. That probably doesn't cover all the places
we'd like the planner to know stuff like this, but it's a reasonable start.
--
Joshua Tolley / eggyknap
End Point Corporation
http://www.endpoint.comAttachments:
signature.asc (application/pgp-signature, 835B) download
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: eggyknap@gmail.com, nik9000@gmail.com, hlinnakangas@vmware.com
Subject: Re: Thinking About Correlated Columns (again)
In-Reply-To: <5193e08b.8271440a.1813.1075@mx.google.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox