title: elasticsearch: rename output fields of query
body: <p>Is there a way to rename the output fields from an elasticsearch query (like the "select .. AS .." in SQL)? I want to keep the original names of the fields in the index, and only modify their names in the result of the query.</p>
  
  <p>I've read <a href="https://groups.google.com/forum/#!topic/elasticsearch/xyeUZ-jSzEo" rel="nofollow">this</a> but it says to re-index the data.</p>