A graph of typed pointers. As you likely know, the basic element of RDF is not “foo has a relationship with bar”, but “foo has a relationship with bar of type baz”.

Also, the types themselves can be part of relationships as in “baz has a relationship with quux of type foobar”

> The thing about graphs is, in general, they are amorphous and could have any structure (or lack of structure) at all which can be a disaster from a memory latency perspective

But that’s an implementation detail ;-)

In theory, the engine you use to store the graph could automatically optimize memory layout for both the data and the types of query that are run on it.

Practice is different.

> Thus practitioners tend to be skeptical about general purpose graph processing libraries

I am, too. I think the thing they’re mostly good for is producing PhD’s, both on the theory of querying them, ignoring performance, and on improving performance of implementations.