I agree that a one-to-one mapping between objects and tables is not always a good idea (not to say it's always a bad idea either - sometimes there is a one-to-one between tables and business objects).

However, I don't think that was the point herveus was making. We're not talking about the process of mapping relational databases to objects.

herveus was saying that there can be useful insights in looking at class/object hierarchies in the context of database design and normalisation.

In particular, refactoring an object hierarchy with lots of objects with duplicate state, to one with fewer objects that share state (aka flyweight pattern) is basically normalisation under another name.

That's how I read it anyway :-)

Update: Judging by the reply it looks like I was misinterpreting herveus, hence stricken text.