RMAN> report unrecoverable database;
Report of files that need backup due to unrecoverable operations
File Type of Backup Required Name
4 full or incremental C:\ORACLE\ORADATA\ORCL\USERS01.DBF
A. There are no backup sets with any backups of the users01.dbf datafile.
B. The users01.dbf datafile has had unrecoverable operations occur in it. It will need to be backed up or some data loss is possible during a recovery.
C. The users01.dbf datafile is corrupted.
D. The users01.dbf datafile backup exceeds the retention criteria.
E. The last backup of the users01.dbf datafile failed and must be rerun.
答案：（B）
解析：
列出所有unrecoverable的数据文件.
一个数据文件被认为是unrecoverable的, 从这个数据文件的上次备份后,对数据文件中存储的对象执行了unrecoverable操作.
在unrecoverable操作中, 不会产生redo数据. 例如表数据的直接加载; 使用NOLOGGING选项更新数据
注意：数据文件不存在任何备份不是认为该数据文件是unrecoverable的充分条件.例如数据文件可以使用CREATE DATAFILE
命令创建, 如果从数据文件创建后,所有的redo log都存在.