Interesting, it looks like you see it in different light. Really, my point was that, first, the problem of automatic mapping doesn't need to be solved - its ok to do it manually IMO, second, I'm even unsure that OO is more efficient in data processing. This is definitely subjective, but in my experience in most cases OO didn't add up much to the clarity of my intentions.

To be honest the incentive for me to post this was mostly accumulated irritatation by the fact that a mere side effect of the mapping turned to countless attempts to model SQL in the host language. Really, IMO, all of them are worse than SQL, all of them waste your time spent learning them, with all of them sooner or later you find yourself in a position when you figure how to express the SQL you want with the DSL at hand (again, it is hard to qualify this other than wasting time).