text: DELIMITER $$
  DROP PROCEDURE IF EXISTS `modify_column_cluster_type_v12` $$
  CREATE PROCEDURE modify_column_cluster_type_v12()
  BEGIN
      IF EXISTS(SELECT * FROM information_schema.columns WHERE table_schema=(select database()) AND table_name='binlog_node_info' AND column_name='cluster_type')
  	THEN
          alter table binlog_node_info modify column `cluster_type` varchar(32) default NULL;
      END IF;
  	IF EXISTS(SELECT * FROM information_schema.columns WHERE table_schema=(select database()) AND table_name='rpl_task' AND column_name='cluster_type')
      THEN
          alter table rpl_task modify column `cluster_type` varchar(32) DEFAULT NULL COMMENT '任务类型';
      END IF;
  END $$
  DELIMITER ;
  CALL modify_column_cluster_type_v12;