| From: | eggyknap <eggyknap(at)gmail(dot)com> |
|---|---|
| To: | Nikolas Everett <nik9000(at)gmail(dot)com> |
| Cc: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, sthomas(at)optionshouse(dot)com, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Thinking About Correlated Columns (again) |
| Date: | 2013-05-15 19:23:25 |
| Message-ID: | 5193e08b.8271440a.1813.1075@mx.google.com |
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| Lists: | pgsql-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.com
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