当试图开启备库的flashback功能时报如下错误：
SQL> alter database flashback on;
alter database flashback on
ORA-01153: an incompatible media recovery is active
ORA-1153, 00000, "an incompatible media recovery is active"
// *Cause: Attempted to start an incompatible media recovery or open resetlogs
// during media recovery or RMAN backup . Media recovery sessions
// are incompatible if they attempt to recover the same data file.
// Incomplete media recovery or open resetlogs is incompatible with
// any media recovery. Backup or restore by RMAN is incompatible
// *Action: Complete or cancel the other media recovery session or RMAN backup
解决方法：先停止应用，然后开启闪回，再次开始应用！
SQL> alter database recover managed standby database cancel;
SQL> alter database flashback on;
SQL> alter database recover managed standby database disconnect from session;