title: How can I query across multiple collections using SolrCloud?
body: <p>Is there any way to search for particular value in all available collections in SolrCloud?</p>
  
  <p>ex.I have 5 collections collection_1,collection_2,collection_3,collection_4,collection_5</p>
  
  <p>each collection has common field 'app_id', I want to search all documents for 'app_id:123' on all of these collections. Is there any way to do this?</p>