thanks for explanation
to perfect my comprehension, what are the side effects of an
"unbalanced" index?

growing file size?
slowing index reading?
more?

Thierry

Helen Borrie a écrit :

> At 07:11 PM 20/02/2007, you wrote:
>
>> considering your answer, is it correct to say that SET STATISTICS
>> requests are now useless?
>>
>
> No, SET STATISTICS hasn't anything to do with whether indexes are
> "balanced" or not (which is physical thing). It recalculates the
> selectivity of the index, i.e. the distribution of values across the
> index or, generically, its usefulness (high=good, low=bad). A unique
> index has the highest selectivity since there is at most one
> occurrence of its value[s]. If you are looking at the statistics
> stored in rdb$indices, those with the high numbers are the least selective.
>
> ./heLen
>