how do you retrieve "the interface" ? can you show us some code
since an interface can not be instantiated you can not persist it. you can only get back an object that implements the given interface.
if you've mapped the interfaces and implementation (as an inheritance hierarchy) then you can get back implementations of a given interface trough Criteria or HGL. e.g.
i think best would be if you show some code and the mapping.
and i've never seen hibernate append "where 1 = 2"

does not make much sense...
pascal