I'm wondering whether we really need to maintain separate access functions that return raw pointer vs shared_ptr to Collection instances from the CollectionCatalog. Could we simplify code by always using shared_ptr? We're moving in that direction anyway, removing locks and supporting versioned instances and copy-on-write.

I suspect that any small performance gain of using a raw pointer instead of a shared_ptr might could irrelevant, if it exists. On the other hand, it would simplify our code to use shared_ptr consistently.