Subject Re: [firebird-support] How to know when an index has become unbalanced?
Author Helen Borrie
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.