[JENA-1001] named graphs set not empty if no FROM NAMED clause given

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Later
• Affects Version/s: Fuseki 2.0.0
• Component/s: Fuseki
• Assignee: Unassigned
• Reporter: Marvin Frommhold
• Created: 29/Jul/15 09:52
• Updated: 02/Aug/15 08:59
• Resolved: 31/Jul/15 18:26

Description

According to the SPARQL 1.1 Query Language specification the set of named graphs must be empty if a query only specifies FROM clauses and no FROM NAMED clauses:

An RDF Dataset comprises ... zero or more named graphs

That means, the only way to express zero named graphs is to specify no FROM NAMED clause.

But:

Having the following data:
http://example.org/graph1

<urn:subject1> rdfs:label "Subject one" .

http://example.org/graph2

<urn:subject2> rdfs:label "Subject two" .

and executing the query:

SELECT ?g
FROM <http://example.org/graph1>
WHERE {
  GRAPH ?g { ?s ?p ?o . }
}

will return

 ?g
===========
 ex:graph1
 ex:graph2

which proves that the set of named graphs is not empty:

GRAPH can ... use a variable which will range over the IRI of all the named graphs in the query's RDF dataset.

Issue Links

• is duplicated by: JENA-1002 specifying a FROM clause still selects from the unnamed default graph
• is superceded by: JENA-1004 Dynamic datasets inconsistently supported in Fuseki.