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

[Andy Seaborne]

On 11/04/17 01:29, Dimov, Stefan wrote:
Another question in that order:

Now:

SELECT count(*)
FROM <http://ao.com/namedGraph/aaa>
{
  { ?s ?p ?o }
}

returns the number of the triples in aaa, correctly, but:

SELECT count(*)
FROM NAMED <http://ao.com/namedGraph/aaa>
{
  { ?s ?p ?o }
}


If you are querying the dataset, you don't need FROM / FROM NAMED: use 
GRAPH to access a named graph:

SELECT count(*)
{
  GRAPH <http://ao.com/namedGraph/aaa>
  { ?s ?p ?o }
}

    Andy

returns zero.

The explanation (in the docs) of the difference between FROM and FROM NAMED is 
a bit confusing and it’s not enough (for me) to understand, why the first is 
working and the second is not …

S.

On 4/10/17, 5:09 PM, "Dimov, Stefan" <stefan.di...@sap.com> 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 …

    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.