title: Filter by datatype
body: <p>I'm trying to filter by datatype in DBpedia. For example:</p>
  
  <pre><code>SELECT *
  WHERE {?s ?p ?o .
      FILTER ( datatype(?o) = xsd:integer) 
      } 
  LIMIT 10
  </code></pre>
  
  <p>But I get no results, while there are certainly integer values. I get the same  from other endpoints using Virtuoso, but I do get results from alternative endpoints. What could be the problem? If Virtuoso does not implement this SPARQL function properly, what to use instead?</p>