Re: Why we don't want hints Was: Slow count(*) again...

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>

To: Bruce Momjian <bruce@momjian.us>

Cc: Kevin Grittner <Kevin.Grittner@wicourts.gov>, sthomas@peak6.com, Josh Berkus <josh@agliodbs.com>, "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>

Date: 2011-02-23T02:22:10Z

Lists: pgsql-hackers, pgsql-performance

On Wed, Feb 16, 2011 at 4:22 PM, Bruce Momjian <bruce@momjian.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
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