Nested relational databases area better fit (Score 1)

If you have a look at the literature, for example the proceedings of VLDB, you'll see that nested relational databases are, in general, the preferred theoretical model. There are a few quirks to iron out where the semantics don't quite align, but on the whole they are the better approach.

Why? Because the relational component still allows set-at-a-time interaction for efficient querying, but path expressions can also be used to navigate through the nested structure.