Subject RE: [firebird-support] Query Performance - correlated subqueries and group by statements
Author Leyne, Sean
> However, Firebird indexes do suffer when there are large (> 10,000)
> numbers of instances of a single value in an index. Check the list
> archives for discussions (many many discussions) of index selectivity.

For the info of other list members (Ann already knows this), Firebird
v2.0 has new disk structure for indexes which significantly (incredibly)
improves the engines performance when handling low selectivity indexes.