As per the other commenter, Cayley provides a graph data model on top of an existing storage layer. However, when we get to manage the storage layer (Bolt, Lev

As per the other commenter, Cayley provides a graph data model on top of an existing storage layer. However, when we get to manage the storage layer (Bolt, Level -- that's being generalized into local-KVs in the next release) we get to build our own indexes for better data management and performance. But there's no reason we can't hand that job off either -- hence supporting multiple (remote) backends. For the local stuff, though, at some point, Bolt is just a very good BTree implementation.