title: Out of the box federated search using Lucene/Solr/ElasticSearch
body: <p>I have a requirement in which I want to search two or more search index when a particular query is being submitted to search server. Is there a way in which I can collectively search two or more search indexes (all of them indexes different things about the same entity being searched for) and get a single set of responses (response from two or more search indexes) when using Lucene/Solr/Elasticsearch?
  If this is not possible I am trying to set up something on the API level where the search indexes are abstracted away from the search clients where the query is submitted to the API &amp; the API under the hood launces searches in parallel to two or more search indexes and combines the results and sends it back? </p>
  
  <p>The point here is that I don't want to reinvent the wheel if there is such an API framework is available or even if its possible using Lucene/Solr/Elasticsearch out of the box or by simply installing a plugin &amp; configuring it?</p>