dataguard备库启动步骤

startup nomount;
挂载数据库
alter database mount standby database;
启用应用重做
alter database recover managed standby database disconnect from session;
取消备库的自动恢复
alter database recover managed standby database cancel;
启动到只读状态
alter database open read only;
在“READ ONLY”状态下进一步启动备库的恢复，实时应用主库日志。
alter database recover managed standby database using current logfile disconnect;