title: Implement created_on and updated_on logic on client side
body: <p>From elasticsearch > 2, there is no <code>_timestamp</code> field. we have to explicitly populate time fields like <code>created_on</code> and <code>updated_on</code></p>
  
  <p>One way i know to populate these fields is check item to be populated is already existing in Database using <code>uid</code> (assume <code>uid</code> generated on client side using some item properties). If item exists in Database, update all fields except <code>created_on</code>. If item does not exist, create entry in database  with item and <code>created_on</code> equal to current time.</p>
  
  <p>My questions are:<br>
   * Isn't checking every time i create/update redundant ??<br>
   * Is there any better way to implement <code>created_on</code> and <code>updated_on</code> logic on client side without redundant (without querying elasticsearch) ??</p>