FROM 关键字不检索远程三元组

Question

The following query works fine with Jena ARQ but in GraphDB it does not retrieve anything:

SELECT *
FROM <http://www.bobdc.com/miscfiles/BeatlesMusicians.ttl>
WHERE { ?s ?p ?o .}

Is there something I need to configure on GraphDB to get this to work?

Answer 1

After reviewing https://www.w3.org/TR/sparql11-query/ it looks to me like the spec is saying that treating the FROM URI as a URL and retrieving triples from that location is something that the query engine can do but is not required to do.

Section 13.2 says that FROM specifies an IRI, which sounds like it's talking about a named graph and not necessarily a remote dataset to retrieve (that is, treating the URI as a URL), which is what I was looking for.

Section 13.2.3 does have "FROM http://example.org/dft.ttl " in one of its examples, which looks to me like it's specifying a Turtle file on some remote server to read into the default graph, like I was trying to do.

Section 21 says "SPARQL queries using FROM, FROM NAMED, or GRAPH may cause the specified URI to be dereferenced," but as we see from the word "may", does not require it. (The rest of that paragraph has a little more about this.)

I have found that the Jena tools arq and fuseki do this, but GraphDB and Blazegraph do not.