On Mon, 05 Dec 2005 10:11:41 -0500, Tom Lane <tgl@sss.pgh.pa.us>
wrote:
>> Correlation -0.0736492
>> Correlation -0.237136
>That has considerable impact on the
>estimated cost of an indexscan
The cost estimator uses correlationsquared. So all correlations
between -0.3 and +0.3 can be considered equal under the assumption
that estimation errors of up to 10% are acceptable.
Servus
Manfred