Comment 15 for bug 788590

What is an "owned child"? That sounds contradictory (or rather, the
idea that a parent owns its child is OK, but the idea that the child
owns its parent is not). I think a two-way one-to-many relationship
can be modelled but it needs to be the case that the "one" is the
parent of the "many". This means that the "one" would have a set of
keys linking it back to the "many", but they would just be keys, not
objects in the way that the child would refer to the parent.

I don't know if JDO was a mistake. It seems like an annoying
abstraction -- it's a nice way of thinking about things, but then they
break and you need to know about the details under the abstraction. An
abstraction where you need to know the details underneath is worse
than no abstraction at all. It looks like Java App Engine gives you a
much lower level view of the datastore, but it is too low! The Python
App Engine gives you a middle-level view (somewhere in between the
Java low-level view and the JDO view), which seems about right. So I
very much prefer the Python App Engine.