title: Multiple-index searching in Lucene (hibernate search)
body: <p>Official Lucene Feautures site states that lucene supports "multiple-index searching with merged results".</p>
  
  <p>Is it possible to do this with hibernate search somehow?</p>
  
  <p>My usecase: Aricle with Comments. I want to have two separate indices: one for articles and one for comments. I want to be able  to find article also by match in one of comments. From user perspective, I want search that "looks" into article text and also its comments and returns list of articles.
  (I know I can implement this by storing all comments as fields inside article document, but I want to apply filters on search in comments.)</p>
  
  <p>Is it even possible with native Lucene or I/m completely missing the point?</p>