Re: [PERFORM] Bad n_distinct estimation; hacks suggested? - Mailing list pgsql-hackers

From Josh Berkus
Subject Re: [PERFORM] Bad n_distinct estimation; hacks suggested?
Date
Msg-id 200504231653.16317.josh@agliodbs.com
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In response to Re: [PERFORM] Bad n_distinct estimation; hacks suggested?  (Josh Berkus <josh@agliodbs.com>)
List pgsql-hackers
People,

> Can someone whose math is more recent than calculus in 1989 take a look at
> that paper, and look at the formula toward the bottom of page 10, and see
> if we are correctly interpreting it?    I'm particularly confused as to
> what "q" and "d-sub-n" represent.  Thanks!

Actually, I managed to solve for these and it appears we are using the formula
correctly.  It's just a bad formula.

--
--Josh

Josh Berkus
Aglio Database Solutions
San Francisco

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