title: Consider adding .indexOn for Firebase
body: <p>I have a Firebase database as :</p>
  
  <pre><code> "requested_rides" : {
  "2016-10-04" : {
    "-KT9F_8DJHmKj33PW70w" : {
      "added_on" : 1475493385140,
      "code" : "AQZ66I4QP4",
      "date_of_ride" : "2016-10-04 AD 04:22 AM GMT+05:45",
      "day" : "Tomorrow",
      "dropoff_coordinate" : "27.6953541,85.2965062",
      "dropoff_location" : "Chunne Pakha",
      "fullname" : "bhaskarraj93@gmail.com",
      "offered_by" : "v1tENP2TaUVHaZFhSGuZ4M6cJJU2",
      "pickup_coordinate" : "27.716454540107783,85.32458111643793",
      "pickup_location" : "Kuber Plazza, Kathmandu 44600, Nepal",
      "seats" : "2",
      "share" : "578",
      "time" : "04:22 AM",
      "vechile_type" : "Bike"
    }
  },
  </code></pre>
  
  <p>I have added rules to the database but I am getting this error</p>
  
  <p>Consider adding <code>".indexOn": "code"</code> at /requested_rides/2016-11-23 to your security and Firebase rules for better performance</p>
  
  <p>The rule that I defined is </p>
  
  <pre><code>"rules":{
      ".read":true,
      ".write":true,
      "requested_rides":{
          ".indexOn":"code"
      }
  }
  </code></pre>