OCP-1Z0-053-V12.02-660题

660.You want to configure the Flashback Database feature and retain flashback logs for three days.

Presently the database is open and configured in ARCHIVELOG mode.

The following steps must be performed in the correct sequence to do this:

1. Set the retention target:

SQL> ALTER SYSTEM SET DB_FLASHBACK_RETENTION_TARGET=4320;

2. Enable Flashback Database:

SQL> ALTER DATABASE FLASHBACK ON;

3. Mount the database:

SQL> STARTUP MOUNT EXCLUSIVE

4. Shutdown the instance:

SQL> SHUTDOWN IMMEDIATE

5. Open the database:

SQL> ALTER DATABASE OPEN;

Choose the correct sequence.

A. 4, 1, 3, 2, 5

B. 4, 3, 1, 2, 5

C. 2, 4, 3, 5, 1

D. 4, 2, 5, 3, 1

Answer: B

答案解析：

sys@TEST0910> archive log list;

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     1

Next log sequence to archive   3

Current log sequence           3

sys@TEST0910> shutdown immediate;                                                                                                          

Database closed.

Database dismounted.

ORACLE instance shut down.

sys@TEST0910> startup mount exclusive

ORACLE instance started.

 

Total System Global Area 2505338880 bytes

Fixed Size                  2230952 bytes

Variable Size             587203928 bytes

Database Buffers         1895825408 bytes

Redo Buffers               20078592 bytes

Database mounted.

sys@TEST0910> alter system set db_flashback_retention_target=4320;

 

System altered.

 

sys@TEST0910> alter database flashback on;

 

Database altered.

 

sys@TEST0910> alter database open;

 

Database altered.

 

 

To enable flashback logging:

1. Ensure the database instance is open or mounted. If the instance is mounted, then the database must be shut down cleanly unless it is a physical standby database. Other Oracle RAC instances can be in any mode.

2. Optionally, set the DB_FLASHBACK_RETENTION_TARGET to the length of the desired flashback window in minutes:

   ALTER SYSTEM SET DB_FLASHBACK_RETENTION_TARGET=4320; # 3 days

   By default DB_FLASHBACK_RETENTION_TARGET is set to 1 day (1440 minutes).

3. Enable the Flashback Database feature for the whole database:

   ALTER DATABASE FLASHBACK ON;

官方参考：http://docs.oracle.com/cd/E11882_01/backup.112/e10642/flashdb.htm#CFHEHEBA