Pavel,

P> Who is talking about maintaining uniqueness at the application level?

Ann, in her initial post talked about unique indexes; Lars, as
requested, posted an example. You replied to Lars.
I buy Ann's argument that "if that capability were internalized,
Firebird could also do the second check to recognize whether a hash
collision was actually a match or just a collision", something which
would be inefficient to do at the application level.

All in all I don't see a problem with the feature, I don't even see it
as a feature, but merely the removal of a limit on index size that
Firebird does carry and others don't.

Ciao
--
Nando Dessena