title: High replication datastore consistency across instances
body: <p>A pretty simple question really. Are queries consistent across instances? </p>
  
  <p>I understand that with the following query, I may miss some newly <code>put</code> entities.</p>
  
  <pre><code>messages = Message.all().filter('user =', current_user).fetch(20)
  </code></pre>
  
  <p>However, is it safe to assume that once an entities is returned from this query, it will always be returned by it <em>(ignoring the fact that it may not be in the first 20)</em>?</p>
  
  <p>If so, does it extend to other queries of the same entity (using a different index)</p>
  
  <pre><code>messages = Message.all().filter('user =', current_user)
                          .filter('posted &gt;', old_date) .fetch(20)
  </code></pre>