title: SPARQL CONSTRUCT; not all results are retrieved
body: <p>I am tying to construct an RDF graph containing films and their labels on <a href="https://query.wikidata.org" rel="nofollow noreferrer">Wikidata SPARQL query service</a>. 
  Basically, this is the query I thought would be sufficient:</p>
  
  <pre><code>CONSTRUCT{
    ?film wdt:P31 wd:Q11424 .
    ?film rdfs:label ?filmLabel.
  }
  WHERE{
    ?film wdt:P31 wd:Q11424 .
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en, [AUTO_LANGUAGE]". }
  }
  </code></pre>
  
  <p>It seems like not all films appear in the results (127636 results), what I note is that the films which don't appear are basically the ones without labels. </p>
  
  <p>However, a <code>SELECT</code> query for the same information returns more results (215734):</p>
  
  <pre><code>SELECT ?film ?filmLabel
  WHERE{
    ?film wdt:P31 wd:Q11424 .
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en, [AUTO_LANGUAGE]". 
    }
  }
  </code></pre>
  
  <p>It seems like not all variables bindings meeting the <code>WHERE</code> clause (the <code>WHERE</code> clause is shared between both queries) are used in the <code>CONSTRUCT</code> at the first query, but all of them are used in the <code>SELECT</code>. </p>
  
  <p>Why is that? Am I missing something somewhere?</p>