ODBC is a layer, is it not (I am really not an expert there), that gives you a standard way to access different kinds of database. DBI is a layer that gives you a standard way to access different kinds of database. I am sure one could generate enough material for ten threads just talking about their differences, but this is the conceptual overlap that I was talking about.

By using DBD::ODBC as your go-to guy, aren't you condemning yourself to using two abstraction layers most of the time? PostgreSQL (or another database) at the bottom, ODBC on top of that, DBI on top of that and your logic on top. Town Musicians of Bremen, where the Dog and the Cat do similar gigs. What would we lose by putting the Dog out to pasture?

There may well be problems (certain combinations of Perl, DB etc.) that are best (or only) solved by having the Dog in there, but I thought that wouldn't make the best default solution.