TerminusDB does use a Datalog-like language as the query language for its public web API. Datalog has long seemed to me to be the obvious "next step" for query

TerminusDB does use a Datalog-like language as the query language for its public web API. Datalog has long seemed to me to be the obvious "next step" for query languages as it enables richer manipulations than those provided by vanilla SQL-like languages in a clean fashion. However, as j-pb noted in another comment: "GraphQL queries describe Tree unfoldings of graphs, and thus return trees. Datalog describes recursive conjunctive queries on hypergraphs (relational model) without or limited negation, and thus return a set or bag of hypergraph edges." TerminusDB allows you to use both approaches. Due to the way we have designed our graphs, with a strongly typed schema langage, you can extract sub-graphs as unfolded trees using a special predicate exposed in our datalog language. This approach (hopefully) gives the best of both worlds, allowing graph traversal and extraction of objects/documents in a single framework, all communicating information via JSON-LD.