本文主要是介绍oracle ADG主备切换，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
1.主库切换备库
SQL> select name,open_mode,switchover_status from v$database;NAME OPEN_MODE SWITCHOVER_STATUS
--------- -------------------- --------------------
PROD1 READ WRITE TO STANDBYSQL> alter system switch logfile;System altered.SQL> alter system archive log current;System altered.SQL> alter database commit to switchover to physical standby with session shutdown;Database altered.SQL> shutdown abort
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.Total System Global Area 849530880 bytes
Fixed Size 1348244 bytes
Variable Size 511708524 bytes
Database Buffers 331350016 bytes
Redo Buffers 5124096 bytes
Database mounted.
SQL> select switchover_status from v$database;SWITCHOVER_STATUS
--------------------
RECOVERY NEEDEDSQL> alter database open;Database altered.SQL> select switchover_status from v$database;SWITCHOVER_STATUS
--------------------
TO PRIMARY
2.备库切换主库
这里可能会出现错误：
ORA-16139: media recovery required。
下面有解决方法
解决完后，可以不要再次执行了。直接执行下面的命令。
SQL> alter database commit to switchover to primary with session shutdown;
alter database commit to switchover to primary with session shutdown
*
ERROR at line 1:
ORA-16139: media recovery required怀疑可能是由于有日志未应用造成的，执行如下语句查询：
SQL> select APPLIED,SEQUENCE# from v$archived_log;APPLIED SEQUENCE#
--------- ----------
YES 8
YES 9
YES 12
YES 13
YES 15
YES 16
YES 17
YES 10
YES 14
YES 11
YES 19APPLIED SEQUENCE#
--------- ----------
YES 18
NO 20
NO 21
NO 22
NO 2316 rows selected.正确步骤：SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;Database altered.SQL> alter database commit to switchover to primary;Database altered.SQL> alter database open;Database altered.SQL> select name,open_mode,switchover_status from v$database;NAME OPEN_MODE SWITCHOVER_STATUS
--------- -------------------- --------------------
PROD1 READ WRITE TO STANDBY
3. 新备库（原主库）启用实时日志应用
SQL> alter database recover managed standby database using current logfile disconnect from session;
Database altered.
SQL> select name,open_mode,switchover_status from v$database;NAME OPEN_MODE SWITCHOVER_STATUS
--------- -------------------- --------------------
RMANPRI READ ONLY RECOVERY NEEDED
4.新主库切换日志
SQL> alter system switch logfile;System altered.
5、分别查看当前主备库切换后当前日志序列号
主库：SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /oracle/archive
Oldest online log sequence 52
Next log sequence to archive 54
Current log sequence 54备库：SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /oracle/archive
Oldest online log sequence 53
Next log sequence to archive 0
Current log sequence 54
6、查看当前主备库状态
主库：SQL> select name,open_mode,switchover_status from v$database;NAME OPEN_MODE SWITCHOVER_STATUS
--------- -------------------- --------------------
RMANPRI READ WRITE TO STANDBY备库：SQL> select name,open_mode,switchover_status from v$database;NAME OPEN_MODE SWITCHOVER_STATUS
--------- -------------------- --------------------
RMANPRI READ ONLY WITH APPLY NOT ALLOWED
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