Re: Re: Density statistic calculation in case of histogram
- From: "Alberto Dell'Era" <alberto.dellera@xxxxxxxxx>
- To: neeraj.dba@xxxxxxxxx
- Date: Thu, 9 Apr 2009 00:14:31 +0200
On Mon, Apr 6, 2009 at 17:20, Neeraj Bhatia <neeraj.dba@xxxxxxxxx> wrote:
> Basically I am interested to know how density is calculated in case of
> height-based histograms. Also, how CBO calculate selectivity.
I wouldn't investigate too much the density in 10.x since the formula
has changed (to a very intuitive one) in 11gR1:
http://www.adellera.it/investigations/11g_newdensity/index.html
so, the 10.x formula has been "deprecated" by the kernel developers.
I did find a statistical justification for the 10.x computation, but
I have never "published" it for the above reasons, it is no longer
important.
hth
alberto
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