def insert(self, topic, content, author_id):
      try:
         table = self.mapper.local_table

         if not self.parent_table_name:
            raise NoMsgBoardFoundError, "parent table should be defined"

         # Lock Parent table's row before adding elements to parent's write
         l = metadata.engine.text("SELECT id from %s where id = :parent_id for UPDATE" % self.parent_table_name,
                                                         bindparams=[bindparam('parent_id', type=types.Integer)]
                                 )
         l.execute(parent_id=self.parent_id)

         # Execute the insert on the msg_board data table with lock held on parent
         t = metadata.engine.text("UPDATE %(table)s SET rgt=rgt + 2 WHERE rgt >= :insert_node_val and parent_id = :parent_id; " 
                                  "UPDATE %(table)s SET lft=lft + 2 WHERE lft >= :insert_node_val and parent_id = :parent_id; "
                                  "INSERT INTO %(table)s (parent_id, topic, content, depth, author_id, rank, lft, rgt, created, updated) "
                                    "values(:parent_id, :topic, :content, :depth, :author_id, "
                                             ":rank, :insert_node_val, :insert_node_val + 1, NOW(), NOW()); "
                                            % {'table': table.name}, 
                                              bindparams=[bindparam('insert_node_val', type=types.Integer),
                                                       bindparam('parent_id', type=types.Integer),
                                                       bindparam('depth', type=types.Integer),
                                                       bindparam('topic', type=types.String),
                                                       bindparam('content', type=types.String),
                                                       bindparam('rank', type=types.Integer),
                                                       bindparam('author_id', type=types.Integer)
                                                      ]
                           )

         t.execute(table_name=table.name, depth=self.depth+1, insert_node_val=self.rgt, 
                     parent_id=self.parent_id, topic=topic, rank=self.rank, content=content, author_id=author_id)
         self.rgt += 2
         self.clear()
      except Exception, msg: 
         print "Exception while inserting into msgboard: ", msg
         pass