Svein Erling Tysvær wrote:

>> For unique indexes and the indexes created to
>> support unique and primary key constraints, the selectivity is
>> known in advance, so you don't need to reset it.
>
> Is this true also for multicolumn indexes in newer Firebird
> versions where the selectivity is calculated for parts of indexes?
> I'm just curious, I never use multicolumn PKs myself.

No - with multi-column indexes resetting the selectivity is a
good idea. And Dmitry S says that it can also affect single
key primary and unique indexes ...

Good luck,

Ann