gistfile1.txt

 Given the following articles ( I haven't loaded the comments yet so this structure will do for illustration ):

{
   "article" : {
      "title" : "article 1",
      "comment" : [ 
         { "text":"mytext1", "date": "2013-11-21", "author": "matt"  },
         { "text":"mytext2", "date": "2013-12-01", "author": "matt" }
      ]
   }
}

{
   "article" : {
      "title" : "article 2",
      "comment" : [ 
         { "text":"mytext3", "date": "2014-01-21", "author": "matt" },
         { "text":"mytext4", "date": "2014-02-01", "author": "matt" }
      ]
   }
}

I can execute a query that returns:

{
  "hits" : [
    {
      "_id" : 1,
      "_source" : {
        "title" : "article 1",
        "comment" : { "text" : "mytext2", "date" : "2013-12-01" }
      }
    },
    {
      "_id" : 2,
      "_source" : {
        "title" : "article 2",
        "comment" : { "text" : "mytext4", "date" : "2014-02-01" }
      }
    }
  ]
}