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Posted to dev@jena.apache.org by "Andy Seaborne (JIRA)" <ji...@apache.org> on 2015/08/02 11:00:11 UTC
[jira] [Commented] (JENA-1001) named graphs set not empty if no
FROM NAMED clause given
[ https://issues.apache.org/jira/browse/JENA-1001?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14650658#comment-14650658 ]
Andy Seaborne commented on JENA-1001:
-------------------------------------
JENA-1004 resolved.
> 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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