You observe that database performance has degraded over a period of time. While investigating the reason， you find that the size of the database buffer cache is not large enough to cache all the needed data blocks. 
Which advisory component would you refer to， in order to determine the required size of the database buffer cache？（）

多项选择题WhatarethetwoadvantagesofRMANBlockMediaRecovery（BMR）overfile­levelrecovery？（）

A.BMR lowers the mean time to recover （MTTR）.
B.BMR supports point­in­time recovery of individual data blocks.
C.BMR enables you to use incremental backups for block recovery.
D.BMR enables recovery even when the database is not mounted or open.
E.BMR enables you to use proxy backups to perform block media recovery.
F.BMR enables increased availability of data during recovery because the data file that requires a recovery can remain online.

单项选择题You execute the following RMAN commands in the order shown below：  BACKUP VALIDATE DATABASE  BLOCKRECOVER CORRUPTION LIST  What will these commands do？（）

A.create a backup of the database and recover all corrupted blocks found in the backup
B.run a backup validation and list all the logically corrupt blocks as well as physically corrupt blocks in the database
C.run a backup validation to populate V$COPY_CORRUPTION view， and then list any corrupt blocks recorded in the view
D.run a backup validation to populate V$DATABASE_BLOCK_CORRUPTION view， and then repair any corrupt blocks recorded in the view
E.run a backup validation， repair any corrupt blocks found during the validation process， and then update V$DATABASE_BLOCK_CORRUPTION view to indicate which corrupt blocks have been repaired

单项选择题Your database is open and running in ARCHIVELOG mode. You take RMAN full backups every Sunday night. On Monday morning， while querying the user1.employees table， you receive the following error message：  01578： ORACLE data block corrupted （file # 5， block # 51） ORA­01110： data file 5： ’ u01 app oracle oradata orcl example01.dbf’  You need to rectify the corruption while ensuring the following： The data file should remain online.  The mean time to recover （MTTR） should be minimal.  You are not using a backup control file， and all the archived logs are accessible. Which option would you choose？（）

A.flash back the corrupted blocks
B.use the DBMS_REPAIR package
C.use the RMAN TSPITR command
D.use the RMAN BLOCKRECOVER command
E.use the RESTORE DATABASE and RECOVER DATABASE commands
F.investigate the time at which the corruption occurred and perform a point­in­time recovery

单项选择题Byusingthetransactionidentifierprovidedby（）foraparticularrowchange，youcanusetheFlashbackTransactionQuerytoseetheoperationperformedbythetransaction.

A.Flashback Table
B.Flashback Database
C.Flashback Versions Query
D.the RMAN REPORT command
E.the DBA_PENDING_TRANSACTIONS view

单项选择题You executed the following query：  SELECT operation， undo_sql， table_name  FROM flashback_transaction_query  Which statement is correct regarding the query output？（）

A.It would return information regarding only the last committed transaction.
B.It would return only the active transactions in all the undo segments in the database.
C.It would return only the committed transactions in all the undo segments in the database. 
D.It would return both active and committed transactions in all the undo segments in the database.
E.It would return information regarding the transactions that began and were committed in the last 30 minutes.