code: def WriteClientStats(self,
                         client_id,
                         stats,
                         cursor=None):
      
  
      try:
        cursor.execute(
            """
            INSERT INTO client_stats (client_id, payload, timestamp)
            VALUES (%s, %s, FROM_UNIXTIME(%s))
            ON DUPLICATE KEY UPDATE payload=VALUES(payload)
            """, [
                db_utils.ClientIDToInt(client_id),
                stats.SerializeToString(),
                mysql_utils.RDFDatetimeToTimestamp(rdfvalue.RDFDatetime.Now())
            ])
      except MySQLdb.IntegrityError as e:
        if e.args[0] == mysql_error_constants.NO_REFERENCED_ROW_2:
          raise db.UnknownClientError(client_id, cause=e)
        else:
          raise
docs: Stores a ClientStats instance.