| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, sthomas(at)peak6(dot)com, Josh Berkus <josh(at)agliodbs(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Why we don't want hints Was: Slow count(*) again... |
| Date: | 2011-02-23 02:22:10 |
| Message-ID: | AANLkTimjt7PGuSyXFsedjCsANzMiVYNDfUUaPJ6_wqrr@mail.gmail.com |
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| Lists: | pgsql-hackers pgsql-performance |
On Wed, Feb 16, 2011 at 4:22 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> I am not excited about the idea of putting these correlations in
> queries. What would be more intesting would be for analyze to build a
> correlation coeffficent matrix showing how columns are correlated:
>
> a b c
> a 1 .4 0
> b .1 1 -.3
> c .2 .3 1
>
> and those correlations could be used to weigh how the single-column
> statistics should be combined.
If you can make it work, I'll take it... it's (much) easier said than
done, though.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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