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

[Dimov, Stefan]

I (almost) got it.

Apparently, the data was loaded correctly. Now I can query the names of all the 
graphs:

SELECT DISTINCT $g
{
   GRAPH ?g { ?s ?p ?o }
}

returns:

{
  "head": {
    "vars": [ "g" ]
  } ,
  "results": {
    "bindings": [
      {
        "g": { "type": "uri" , "value": "aaa" }
      } ,
      {
        "g": { "type": "uri" , "value": "bbb" }
      } ,
      {
        "g": { "type": "uri" , "value": "ccc" }
      } ,
      {
        "g": { "type": "uri" , "value": "ddd" }
      } ,
      …

or the data:

SELECT count(*)
{
   GRAPH ?g { ?s ?p ?o }
}

returns:

{
  "head": {
    "vars": [ ".1" ]
  } ,
  "results": {
    "bindings": [
      {
        ".1": { "type": "literal" , "datatype": 
"http://www.w3.org/2001/XMLSchema#integer"; , "value": "395721" }
      }
    ]
  }
}

but I still can’t figure out how to query specific named graph. This:

SELECT count(*)
{
   GRAPH <aaa> { ?s ?p ?o }
}

should work. But actually it returns zero results:

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

Any idea?

S.


On 4/10/17, 2:06 PM, "Dimov, Stefan" <stefan.di...@sap.com> 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);
        ds.begin(ReadWrite.WRITE);
        FileManager.get().readModel(model, fileName);
        ds.commit();
        ds.end();
        return true;
    }
    
    
    
    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.