## document sample
{
   "_id": "4e5ce8d5ed309a8ffaf40ad4a203c480",
   "_rev": "1-f12acc136489569c916314432b960ab6",
   "user_id": 8852232661,
   "text": "abc",
   "tags": {
       "abc": 1,
       "def": 0,
       "ghi": 0
   },
   "created_at": "Sat Apr 02 08:36:49 +0000 2011"
},
{
   "_id": "4e5ce8d5ed309a8ffaf40ad4a203c480",
   "_rev": "1-f12acc136489569c916314432b960ab6",
   "user_id": 8852232661,
   "text": "abc",
   "tags": {
       "abc": 1,
       "def": 1,
       "ghi": 0
   },
   "created_at": "Sat Apr 02 08:36:49 +0000 2011"
}

## view output

tags: {
  "abc" : 2
  "def" : 1
  "ghi" : 0
}