OCP 1Z0 052 88

88. Identify two situations in which you can use Data Recovery Advisor for recovery. (Choose two.) 
A.The database files are corrupted when the database is open. 
B.The user has dropped an important table that needs to be recovered. 
C.The archived redo log files are missing for which the backup is not available. 
D.The database is not opening because the required database files are missing. 
Answer: AD

B flash back drop 不需要Data Recovery Advisor，也不需要开启归档，只要开启了回收站就可以了

SQL> show parameter recyclebinNAME                                 TYPE        VALUE------------------------------------ ----------- ------------------------------recyclebin                           string      on

C 没备份的归档日志丢了。这个只有看os层面能否恢复了，当然最好别报什么希望。


见 http://docs.oracle.com/cd/E11882_01/server.112/e25494/diag.htm#ADMIN12487

Data Recovery Advisor can diagnose failures such as the following:

• Components such as datafiles and control files that are not accessible because they do not exist, do not have the correct access permissions, have been taken offline, and so on

• Physical corruptions such as block checksum failures and invalid block header field values

• Inconsistencies such as a data file that is older than other database files

• I/O failures such as hardware errors, operating system driver failures, and exceeding operating system resource limits (for example, the number of open files)

The Data Recovery Advisor may detect or handle some logical corruptions. In general, corruptions of this type require help from Oracle Support Services.