> both you and Guido seem to imply that the value that you set with SET
> STATISTICS is the selectivity of an index.
> AFAIK it's not, they are two different figures entirely.
> In particular, I don't think that the selectivity of an index is
> something that IB keeps track of or use. It can be much more frequently
> found in these lists than in IB's documentation. ;-)
> Ciao
> --
> ____
> _/\/ando

this is from the language reference:
RDB$STATISTICS
Selectivity factor for the index; the optimizer uses index selectivity, a
measure of uniqueness for indexed columns, to choose an access
strategy for a query


Guido