title: Elastic search how to add new field and put value from existing field
body: <p>I have a elastic search index as follows,</p>
  
  <pre><code> {
    "payment_transaction": {
      "mappings": {
        "message_logs": {
          "properties": {
            "@timestamp": {
              "type": "date"
            },
            "changed_date": {
              "type": "date"
            },
            "created_date": {
              "type": "date"
            }
          }
        }
      }
    }
  }
  </code></pre>
  
  <p>And I need to add another three fields(year,month,day).And need to assign values from the existing field (created_date). The format of the created_date is <strong>2016-11-22T22:20:21.000Z</strong>. How can i do this ?
  Elastic search version is 5.0.</p>