title: Why does Salesforce prevent me from creating a Push Topic with a query that contains relationships?
body: <p>When I execute this code in the developer console</p>
  
  <pre><code>PushTopic pushTopic = new PushTopic();
  pushTopic.ApiVersion = 23.0;
  pushTopic.Name = 'Test';
  pushTopic.Description = 'test';
  pushtopic.Query = 'SELECT Id, Account.Name FROM Case';
  insert pushTopic;
  System.debug('Created new PushTopic: '+ pushTopic.Id);
  </code></pre>
  
  <p>I receive this message:</p>
  
  <blockquote>
    <p>FATAL ERROR System.DmlException: Insert failed. First exception on row
    0; first error: INVALID_FIELD, relationships are not supported:
    [QUERY]</p>
  </blockquote>
  
  <p>The same query runs fine on the Query Editor, but when I assign it to a Push Topic I get the INVALID_FIELD exception.</p>
  
  <p>If the bottom line is what the exception message says, that relationships are just not supported by Push Topic objects, how do I create a Push Topic object that will return the data I'm looking for?</p>