Oh, God... But they said sometime ago we'd soon have bitmap indices over non-integer fields!
I'm not sure about the "remarkable bit of coding part" - Phil Pybus has been doing it in HyperIndex for nearly four years now. It amounts to keeping an extra global: ^IDTranslation(1)=parent||child ^IDTranslation(2)=parent||child . . . and bitmap indexing that global's subscript. Of course, the query optimizer/generator has to take this into account... But I'd swear I even saw a proof of concept of this at some time :( (Then again it's 2 AM at York and here I am reading the newsgroup... All bets are off! :))
