oracle数据库切换DG步骤
备注：应用服务要先停止对外服务
1.先将主库切换成备库，然后将原主库启动到物理库的状态
SQL> Alter database commit to switchover to physical standby with session shutdown; 2.关闭主库
SQL> shutdown immediate; 3.打开数据库nomount
SQL> startup nomount; 4.更改主库为备库
SQL> alter database mount standby database;SQL> alter database recover managed standby database disconnect from session; 如果配置了 standby redo log 并需要启用实时同步则执行以下代码
SQL>alter database recover managed standby database using current logfile disconnect from session; 5.将备库切换成主库
SQL> select switchover_status from v$database;SQL> select * from v$version where rownum<2;SQL> alter database commit to switchover to primary with session shutdown; 如果备库还有未应用的日志则执行
SQL>alter database recover managed standby database disconnect from session;SQL> shutdown immediate;SQL> startup; 切换日志进行检查
SQL> select max(sequence#) from v$log;SQL>select sequence#,applied from v$archived_log;SQL> alter system switch logfile; 
