On Fri, 08 Aug 2003 18:25:41 -0400, Tom Lane <tgl@sss.pgh.pa.us>
wrote:
> Two examples: [...]
One more example:X Y
A Aa BA Cb AB Bb CC Ac BC C
Correlation for column X is something less than 1.0, OTOH correlation
for an index on upper(X) is 1.0.
>I don't really see
>a way to do this without actually examining the multi-column ordering
>relationship during ANALYZE.
So did we reach consensus to add a TODO item?
* Compute index correlation on CREATE INDEX and ANALYZE, use it for index scan cost estimation
ServusManfred
