逻辑DataGuard SwitchOver

1、查看主库是否处于to standby状态

SQL> select switchover_status from v$database;

2、将primary置为准备转换standby的状态： 

SQL> alter database prepare to switchover to logical standby;

3、此时检查主库的Switchover状态为PREPARING SWITCHOVER。如果不是，需要暂停主备切换，排查原因。

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
PREPARING SWITCHOVER

SQL> 

3、将备库设置为准备转换主库的状态

SQL> alter database prepare to switchover to primary;

4、此时检查备库的Switchover状态为PREPARING SWITCHOVER。如果不是，需要暂停主备切换，排查原因。

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
PREPARING SWITCHOVER

SQL> 

5、如果此时想取消主备切换，可以执行下面命令

主库取消
SQL> alter database prepare to switchover cancel;

备库取消
SQL> alter database prepare to switchover cancel;

6、正式开始切换

主库执行:
SQL> alter database commit to switchover to logical standby;

备库执行:
SQL> alter database commit to switchover to primary;

7、在新的备库启用SQL apply

SQL> alter database start logical standby apply immediate;