OpenLink Virtuoso query local/remote .rdf file

Question

Is it possible in Virtuoso open source edition from local endpoint to query local or remote .rdf / .n3 / .turtle files? Or triples have to be in db? I've read somewhere that it's possible to query files directly but can't find how to do it...

If it's not, how can i, on local virtuoso endpoint, query remote endpoints like dbpedia and others?

I tried with FROM, FROM NAMED but can't get it to work in SPARQL query. Returns 0 results from files and from remote endpoints...

Thnx!

Answer 1

Questions specifically regarding Virtuoso are generally best raised on the public OpenLink Discussion Forums, the Virtuoso Users mailing list, or through a confidential Support Case.

That said... Queries against remote files cannot be run through Virtuoso. But, Virtuoso can be told to import those files (whether via the Sponger or otherwise), and then queries can be run against the resultant triples in the local Virtuoso Quad Store.

Queries against remote SPARQL endpoints can be run through Virtuoso, through the mis-named "SPARQL-FED" a/k/a Federated SPARQL. As you'll see in that documentation, FROM and FROM NAMED are not the appropriate keywords -- SERVICE is.