关于切换后，客户端的连接，在mos上有如下解决方法具体参考：
Step By Step Guide On How To Configure And Test Client-Failover For Dataguard Switchover And Failover. [ID 740029.1]
---在主库创建服务
exec dbms_service.create_service('hhkj','hhkj');
---在主库启动服务
exec dbms_service.start_service('hhkj');
---查看服务
select name, failover_method, failover_type, goal, clb_goal from dba_services;
---在主库创建触发器
CREATE OR REPLACE TRIGGER manage_DGservice after startup on database
DECLARE
role VARCHAR(30);
BEGIN
SELECT DATABASE_ROLE INTO role FROM V$DATABASE;
IF role = 'PRIMARY' THEN
DBMS_SERVICE.START_SERVICE('prod_db');
END IF;
END;
/
