Querying for reified data

Support
1

I noticed that a SPARQL query to retrieve reified data is not doing what I expected.

I loaded the following into a new database:

    [ ] a rdf:statement ;
       rdf:subject :john ;
       rdf:predicate :loves ;
       rdf:object :mary .

and ran the following query I Stardog Studio:

select * where { ?s ?p ?o }

which produced the following four results (in csv format):

  _:bnode_eba0b0c7_ba08_44ce_ad37_7aebea77b069_143,rdf:type,rdf:statement
    :john,rdf:typeowl:Thing
    :loves,rdf:typeowl:Thing
    :mary,rdf:typeowl:Thing

Why didn't it produce the reified rdf:subject, rdf:predicate and rdf:object relations?

If I export the database, it does export them.

Tim

2

Did you run the query with reasoning?

3

Ah, yes. Turning that off gives me what was mimssing. Does having reasoning turned on result in only producing the inferred results?

4

Reasoning results all results, not only inferred results. Let me check with the others on this one. It might be the case that Statement being a subclass of Resource has something to do with not getting results for the reification predicates. You specified "statement" (with a lowercase "s"), but in RDF spec it looks like the domain of subject/predicate/object properties would infer the resource to be a Statement.

5

thanks for catching that. If I use Statement and have reasoning on, I get just the three inferred type statements.