参考文献： http://docs.oracle.com/cd/E11882_01/server.112/e41134/role_management.htm#SBYDB5190

系统信息：Linux localhost.localdomain 2.6.18-164.el5 #1 SMP Thu Sep 3 03:33:56 EDT 2009 i686 i686 i386 GNU/Linux

数据库版本：Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production

主库信息：

NAME DB_UNIQUE_NAME DATABASE_ROLE
--------- ------------------------------ ----------------
AARON aaron PRIMARY

备库信息

NAME DB_UNIQUE_NAME DATABASE_ROLE
--------- ------------------------------ ----------------
AARONSTB aaronstb LOGICAL STANDBY

1. 查看主库状态

SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;

SWITCHOVER_STATUS
--------------------
TO STANDBY

如果状态为TO STANDBY或者SESSIONS ACTIVE 表示可以转换为逻辑备库。

2.当前主库准备switchover

SQL> ALTER DATABASE PREPARE TO SWITCHOVER TO LOGICAL STANDBY;

Database altered.

SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;

SWITCHOVER_STATUS

--------------------

PREPARING SWITCHOVER

3. 当前备库准备switchover

SQL> ALTER DATABASE PREPARE TO SWITCHOVER TO PRIMARY;

Database altered.

SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;

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

4. 确保当前主库准备好swithover到备库

SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;

SWITCHOVER_STATUS
--------------------
TO LOGICAL STANDBY

TO LOGICAL STANDBY表示准备好switchover为备库，如果不是此状态，使用如下语句取消switchover

主库：

SQL> ALTER DATABASE PREPARE TO SWITCHOVER CANCEL;

备库：

SQL> ALTER DATABASE PREPARE TO SWITCHOVER CANCEL;

5. 切换当前主库为备库

SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO LOGICAL STANDBY;

Database altered.

6. 确保备库准备好成为主库

SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;

SWITCHOVER_STATUS

--------------------

TO PRIMARY

7. 切换当前备库为主库

SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY;

Database altered.

8. 开启SQL Apply(新备库)

SQL> ALTER DATABASE START LOGICAL STANDBY APPLY IMMEDIATE;

Database altered.

ITPub博客

逻辑备库Switchover

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