title: Haystack: one searchIndex for multiple models
body: <p>On the <a href="https://django-haystack.readthedocs.org/en/latest/tutorial.html" rel="nofollow">getting started page</a> of Haystack, it describes the possibility of using one SearchIndex for multple models: </p>
  
  <blockquote>
    <p>You generally create a unique SearchIndex for each type of Model you
    wish to index, though you can reuse the same SearchIndex between
    different models if you take care in doing so and your field names are
    very standardized.</p>
  </blockquote>
  
  <p>However I haven't found any information regarding how to do so. The reasoning behind it is that a few Heroku search engine apps provide limited amount of indices, so I think it's a good idea to keep the number of indices slim. How should I do it?</p>