Re: When using named graphs, can't query the data

[Andy Seaborne]

On 10/04/17 22:06, Dimov, Stefan wrote:

Hi,

I’m using in-mem base and loading multiple named graphs in one data set, 
iterating thru :

private static boolean loadGraphT(Dataset ds) {
    …
    String filename = …
    String graphName = …
   …
    Model model = ds.getNamedModel(graphName);

Put this inside the transaction

    ds.begin(ReadWrite.WRITE);
    FileManager.get().readModel(model, fileName);
    ds.commit();
    ds.end();
    return true;

> }

     ds.begin(ReadWrite.WRITE);
     Model model = ds.getNamedModel(graphName);
     RDFDataMgr.read(model, fileName);
     ds.commit();
     ds.end();


or even:

        Txn.executeWrite(ds, ()->{
            Model model = ds.getNamedModel(graphName);
            RDFDataMgr.read(model, fileName);
        });

http://jena.apache.org/documentation/txn/

}



At start, after everything is read and data set is committed, I’m printing out 
the graph names and their sizes, to check, if everything was loaded:

2017-04-10 13:50:50 INFO  Ontology:50 - Named graph aaa - 7855 triples
2017-04-10 13:50:50 INFO  Ontology:50 - Named graph bbb - 26 triples
2017-04-10 13:50:50 INFO  Ontology:50 - Named graph ccc - 4 triples
2017-04-10 13:50:50 INFO  Ontology:50 - Named graph ddd - 20000 triples
…

After that I’m trying to query some data from a named graph:

SELECT count ($s)
FROM NAMED <aaa>
{
    { ?s ?p ?o }
}

or trying to query it without specifying graph:

SELECT count ($s)
{
    { ?s ?p ?o }
}

The result is empty:

{
  "head": {
    "vars": [ ".1" ]
  } ,
  "results": {
    "bindings": [
      {
        ".1": { "type": "literal" , "datatype": "http://www.w3.org/2001/XMLSchema#integer"; , 
"value": "0" }
      }
    ]
  }
}

What am I doing wrong?

S.