I imagine if we were writing a new RBDMS that wasn't worried about backwards compatibility we could reduce the number of types flying around internally. I think

I imagine if we were writing a new RBDMS that wasn't worried about backwards compatibility we could reduce the number of types flying around internally. I think there's a lot of historical accident in which exact variants of set are available at which point. A refinement of relational logic based on a base data structure that is a bit more pragmatic (because Codd's logic is close to pragmatic, but does still have a bit of ivory towerism in it; no criticism inteded, it was a huge advance, but I think we could tweak it a bit in modern times, and in his defense I think there were bits in Codd's work that failed to come out to the pragmatic systems for a long time, to their detriment) would probably also be helpful. But in the meantime, back here on the ground, it is nice to at least be working in an RDBMS that can convert back and forth between these things, even if it's still klunky. I remember when I just plain couldn't, and the circumlocutions to do what I wanted to do were bigger than the business logic I needed.