Effectively this is the same; at a sufficient diversity of the first element in the compound key, you'll have almost as many tree nodes as you would if you cons

Effectively this is the same; at a sufficient diversity of the first element in the compound key, you'll have almost as many tree nodes as you would if you considered them subtrees. It can be intuitively easier to think of them as subtrees, though, and that was my point; it's not necessary to know all the implementation details, just generally how the system finds data.