dataguard 管理

alter database open read only;
--备库可启动到read only模式

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;
--备库执行，启动重做应用，DISCONNECT FROM SESSION重做应用运行在后台会话中
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE;
--启用Real Time Apply
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;
--启用RealTimeApply的后台管理模式


alter database open read only;
--备库可启动到read only模式

alter database recover managed standby database cancel;
--取消应用主库日志

alter database recover automatic standby database allow 1 corruption;

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DG搭建重要参数：
db_file_name_convert
log_file_name_convert
standby_file_management
log_archive_dest
log_archive_config