Switchover to a Physical Standby Database

Switchover流程是从Primary Database开始，于Standby Database终止。

步骤如下：

1 在主库端检查数据库可切换状态

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS–>TO STANDBY,表示可以正常切换.

SWITCHOVER_STATUS–>SESSIONS ACTIVE,表示当前有会话处于ACTIVE状态

2 开始主库正常切换

如果SWITCHOVER_STATUS 的值为TO STANDBY：

SQL> alter database commit to switchover to physical standby;

如果SWITCHOVER_STATUS 的值为SESSIONS ACTIVE：

SQL> alter database commit to switchover to physical standby with session shutdown;

3 重启主库

SQL> shutdown abort;
SQL> startup mount;

4 到备库验证可切换状态

SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
-----------------
TO_PRIMARY

5 将目标备库转换为主库

如果SWITCHOVER_STATUS 的值为TO STANDBY 则:

SQL> alter database commit to switchover to primary;

如果SWITCHOVER_STATUS 的值为SESSIONS ACTIVE 则:

SQL> alter database commit to switchover to primary with session shutdown;

6 打开目标备库

SQL> alter database open;

7 开始在目标备库应用日志

SQL> alter database recover managed standby database disconnect;

8 检查主备库角色状态：

SQL> select switchover_status,database_role from v$database;