SQL > Cypher > SPARQL
You can do RDF/SHACL/OWL with LPG/Cypher based databases.
Ontolite (sqlite) and ontobug (ladybug) are examples.
- you need some engine to support your owl/rdf/sparql, and all available are lower quality/perf/features than pg
- its easier for LLMs to talk standard SQL compared so some version of sparql
I’ve used AWS Neptune as a pretty reasonable managed sparql query engine but for most my needs actually just local jsonld mastered in git is plenty for almost APO knowledge graphs I have.
I’ve found LLMs are exceptionally proficient at authoring sparql, and quite clever. This isn’t surprising given there’s plenty of sparql in the corpus, and it’s semantics aren’t HUGELY different than SQL. Likewise they do fine writing datalog etc.
it is obviously not OSS like postgres.
There’s also a lot of books on how to develop ontologies as well as online resources. They are all in the corpus and tasking a frontier pro level model with building a process and mental model document with references inline for grounding works really well as well for priming.