title: Java GAE: Can I filter by comparing the properties of entities?
body: <p>I need to query entities having equal properties, for example:</p>
  
  <pre><code>class Relation {
    Integer a;
    Integer b;
  }
  
  Query q = pm.newQuery(Relation.class);
  q.setFilter("a == b");
  </code></pre>
  
  <p>The above query returns empty list and I haven't found any way to accomplish this task. </p>