oracle DG 主备切换语句整理
DataGuard关启状态启用备用数据库
SQL > STARTUP NOMOUNMT;
SQL >alter database mount standby database;
SQL >alter database recover managed standby database disconnect from session;
启用实时的日志应用 real time apply，开启日志的实时应用需要备库有备重做日志文件的存在。
SQL>>
Database> 停止日志应用服务
SQL>>
Database> 判断当前备库是否启用了日志实时应用，使用如下语句：
SQL> select RECOVERY_MODE from v$archive_dest_status;
RECOVERY_MODE
-----------------------
MANAGED REAL TIME APPLY
1 rows selected.
如果是没有启用日志的实时应用，recovery_mode显示的是MANAGED
关闭备用数据库
SQL >alter database recover managed standby database cancel;
SQL >shutdown immediate;
从关闭状态打开
SQL >startup nomount;
SQL >alter database mount standby database;
SQL >alter database open read only;
从正在恢复状态只读打开
SQL >alter database recover managed standby database cancel;
SQL >alter database open read only;
切换回到恢复状态
SQL >alter database recover managed standby database disconnect from session;
-----日志强制归档
SQL>>
SQL>> -----查看当前保护模式
SQL > select name,db_unique_name,protection_mode from v$database;
-----检查备库归档文件是否连续
SELECT THREAD#, LOW_SEQUENCE#, HIGH_SEQUENCE# FROM V$ARCHIVE_GAP;
-----检查归档文件是否完整，主备执行，看最大序号是否相同，
select distinct thread#,max(sequence#) over(partition by thread#) a from v$archived_log;
正常切换：
主服务器
----查看主库状态
select OPEN_MODE,PROTECTION_MODE,PROTECTION_LEVEL,SWITCHOVER_STATUS from v$database;
----进行切换
alter database commit to switchover to physical standby;
shutdown immediate
startup nomount;
alter database mount standby database;
alter database recover managed standby database disconnect from session；
备用服务器
----查看备库状态
select OPEN_MODE,PROTECTION_MODE,PROTECTION_LEVEL,SWITCHOVER_STATUS from v$database;
----进行切换
alter database commit to switchover to primary；
shutdown immediate;
startup；
非正常切换：（即主服务器当机的情况）启动failover
备服务器
alter database recover managedstandby database finish;
alter database commit to switchover to primary;
shutdown immediate;
startup;
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