[jira] [Created] (JENA-2342) SPARQL query comparing "count(distinct ?v)" values is evaluated incorrectly

["Jakub Galgonek (Jira)" <ji...@apache.org>]

Jakub Galgonek created JENA-2342:
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             Summary: SPARQL query comparing "count(distinct ?v)" values is evaluated incorrectly
                 Key: JENA-2342
                 URL: https://issues.apache.org/jira/browse/JENA-2342
             Project: Apache Jena
          Issue Type: Bug
          Components: SPARQL
    Affects Versions: Jena 4.5.0
            Reporter: Jakub Galgonek


I encountered the following issue while testing the neXtProt database in Jena.

If the query –
{code:sql}
select ?id where {
  values (?id ?v1 ?v2) { ('A' 'B' 'C') }
} group by ?id having (count(distinct ?v1) = count(distinct ?v2))
{code}
– is submitted, then the empty result is returned. However, the result –
{code:java}
( ?id = "A" ){code}
– should by returned.

On the other hand, the query –
{code:sql}
select ?id where {
  {select ?id (count(distinct ?v1) as ?c1) (count(distinct ?v2) as ?c2) {
    values (?id ?v1 ?v2) { ('A' 'B' 'C') }
  } group by ?id}
  filter (?c1 = ?c2)
}
{code}
– returns the result as expected.

The following code can be used to reproduce the issue:
{code:java}
import org.apache.jena.query.QueryExecution;
import org.apache.jena.query.QueryExecutionFactory;
import org.apache.jena.query.ResultSet;
import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.ModelFactory;

public class Test {
  static String query1 = "select ?id where { values (?id ?v1 ?v2) { ('A' 'B' 'C') } } group by ?id having (count(distinct ?v1) = count(distinct ?v2))";
  static String query2 = "select ?id where { {select ?id (count(distinct ?v1) as ?c1) (count(distinct ?v2) as ?c2) { values (?id ?v1 ?v2) { ('A' 'B' 'C') } } group by ?id} filter (?c1 = ?c2) }";

  public static void main(String[] args) {
    evaluate("Query1:", query1);
    evaluate("Query2:", query2);
  }

  public static void evaluate(String name, String query) {
    Model model = ModelFactory.createDefaultModel();
    QueryExecution qexec = QueryExecutionFactory.create(query, model);
    ResultSet results = qexec.execSelect();

    System.out.println(name);
    while(results.hasNext())
      System.out.println(results.nextSolution());
  }
}
{code}



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