Marvin Frommhold created JENA-1001:
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Summary: named graphs set not empty if no FROM NAMED clause given
Key: JENA-1001
URL: https://issues.apache.org/jira/browse/JENA-1001
Project: Apache Jena
Issue Type: Bug
Components: Fuseki
Affects Versions: Fuseki 2.0.0
Reporter: Marvin Frommhold
According to the [SPARQL 1.1 Query Language
specification|http://www.w3.org/TR/2013/REC-sparql11-query-20130321/] the set
of named graphs must be empty if a query only specifies FROM clauses and no
FROM NAMED clauses:
bq. 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
{code}
<urn:subject1> rdfs:label "Subject one" .
{code}
http://example.org/graph2
{code}
<urn:subject2> rdfs:label "Subject two" .
{code}
and executing the query:
{code}
SELECT ?g
FROM <http://example.org/graph1>
WHERE {
GRAPH ?g { ?s ?p ?o . }
}
{code}
will return
{code}
?g
===========
ex:graph1
ex:graph2
{code}
which proves that the set of named graphs is not empty:
{quote}
GRAPH can ... use a variable which will range over the IRI of all the named
graphs in the query's RDF dataset.
{quote}
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