Your query says:
SELECT * WHERE
{GRAPH <http://example.com/graphs/test1/> { ?s ?p ?o . }}
but you are not querying the TDB dataset:
QueryExecutionFactory.create(query, m_triplestore) ;
You are querying one model as the default graph of a temporary dataset.
It is not called <http://example.com/graphs/test1/> in that dataset.
The fact the model is populated by the TDB union of named graphs does
not give the triples any graph names. A model is a set of triples; a
model may be named within a dataset.
Remove the GRAPH part.
SELECT * WHERE { ?s ?p ?o . }
Andy
On 20/03/12 20:36, Milorad Tosic wrote:
I am re-posting the message to the list for the sake of completeness since I
did reply on the personal address by mistake.
Sorry,
Milorad
________________________________
From: Milorad Tosic<[email protected]>
To: Dave Reynolds<[email protected]>
Sent: Tuesday, March 20, 2012 2:27 PM
Subject: Re: is GraphStore deepcopy or a facade?
Hi,
Here is the code segment:
/**
* Select triples in the NamedGraph in the store
*/
querystr = "SELECT * WHERE {GRAPH<http://example.com/graphs/test1/> { ?s
?p ?o . }}";
System.out.println("Running "+querystr);
Query query = QueryFactory.create(querystr);
m_triplestore = ModelFactory.createInfModel(
ReasonerRegistry.getOWLMicroReasoner(),
m_dataset.getNamedModel("urn:x-arq:UnionGraph"));
query.setPrefixMapping(m_triplestore);
m_triplestore.getLock().enterCriticalSection(Lock.READ) ;
try {
QueryExecution qexec = QueryExecutionFactory.create(query,
m_triplestore) ;
ResultSet results = qexec.execSelect() ;
System.out.println("++++++++");
m_dataset.getNamedModel("urn:x-arq:UnionGraph").write(System.out,
"Turtle");
System.out.println("++++++++");
System.out.println("============= Query result m_triplestore
============");
ResultSetFormatter.output(System.out, results,
ResultSetFormat.syntaxText);
System.out.println("============= Query result m_triplestore
============");
qexec.close();
} finally {
m_triplestore.getLock().leaveCriticalSection();
}
while the output segment is:
Running SELECT * WHERE {GRAPH<http://example.com/graphs/test1/> { ?s ?p ?o . }}
++++++++
<http://example.org/book/book99>
<http://purl.org/dc/elements/1.1/creator>
"A.N.Other" ;
<http://purl.org/dc/elements/1.1/title>
"A new book" .
++++++++
============= Query result m_triplestore ============
-------------
| s | p | o |
=============
-------------
============= Query result m_triplestore ============
I think my problem so far was that I expected to be able to query together default graph
and union of named graphs. Since default graph contains triplets while named graphs
contain quads, it could be expected highly unlikely to work. So, I tried to be more
specific by using m_dataset.getNamedModel("urn:x-arq:UnionGraph") but it looks
like it didn't work either?
Milorad
________________________________
From: Dave Reynolds<[email protected]>
To: [email protected]
Cc: Milorad Tosic<[email protected]>
Sent: Tuesday, March 20, 2012 1:47 PM
Subject: Re: is GraphStore deepcopy or a facade?
On 20/03/12 12:21, Milorad Tosic wrote:
Andy,
Thank again. I think I understand what your advice is about. If I use dataset
for every update query as follows:
UpdateRequest updateRequest = UpdateFactory.create(querystr);
GraphStore graphStore = GraphStoreFactory.create(m_dataset) ;
UpdateAction.execute(updateRequest, graphStore);
as well as for every select query as follows:
QueryExecution qexec = QueryExecutionFactory.create(query,
m_dataset) ;
ResultSet results = qexec.execSelect() ;
then everything works perfectly fine and I get all triples that were previously
inserted listed as a result of the
select query.
However, if I want to use reasoner for select queries I would need a Model. It
is true, isn't it? But if I try to use a Model on top of the existing dataset I
got an empty result list:
m_triplestore =
ModelFactory.createInfModel(ReasonerRegistry.getOWLMicroReasoner(),
m_dataset.getDefaultModel());
QueryExecution qexec = QueryExecutionFactory.create(query,
m_triplestore) ;
ResultSet results = qexec.execSelect() ;
If there really is data in the default graph then that should work.
Test it with something like:
m_dataset.getDefaultModel().write(System.out, "Turtle");
Basically, I can not make both Model and GraphStore to work over the same
dataset. Does this mean that a reasoner can not work with (multiple)
named graphs?
The reasoners, and reasoner API, predates datsets. You can reason over
single models (or unions of them) and but can't doing anything useful
reasoning over a dataset as a whole. However, you get a Model out of a
dataset and reason over that just fine.
BTW there it is possible to use reasoners at the Graph level, there is
an InfGraph just as there is an InfModel. However, that doesn't help here.
Dave
