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

[Andy Seaborne]

On 11/04/17 01:09, Dimov, Stefan wrote:
Got it - it’s gotta be a real URI, with http and everything:

       http://ao.com/aaa

 The simple names, like:

       aaa

don’t work …

Relative URIs are resolved (BASE <...>) so tyhey don't sytay as the 
plain name in the query or data.

    Andy




S.


On 4/10/17, 4:22 PM, "Dimov, Stefan" <stefan.di...@sap.com> wrote:

    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.