OCP-1Z0-053-200题-21题-602
QUESTION 21
On Friday at 11:30 am you decided to flash back thedatabase because of a user error that occurred at 8:30 am.
Which option must you use to check whether a flashback operation can recover the database to the specified time?
A. Check the alert log file
B. Query the V$FLASHBACK_DATABASE_LOG view
C. Query the V$RECOVERY_FILE_DEST_SIZE view
D. Query the V$FLASHBACK_DATABASE_STAT view
E. Check the value assigned for the UNDO_RETENTION parameter
Answer: B
同602题：http://blog.csdn.net/rlhua/article/details/12423809
Explanation/Reference:
Section: Flashback Operations & Configuration
select oldest_flashback_scn, oldest_flashback_time from v$flashback_database_log;
SYBEX Oracle 1Z0-053 Study Guide, Chapter 9: Understanding Flashback Technology
Query the V$FLASHBACK_DATABASE_LOGto determine the amount of space required in the recovery area to support the flashback activity generated by changesin the database.
The values in the OLDEST_FLASHBACK_SCNand OLDEST_FLASHBACK_TIME columns give you information regarding how far back you can use Flashback Database.
Oracle Press 1Z0-053 Exam Guide, Chapter 9: Configuring and Using Flashback
You can determine how far back you can flashback the database by querying the V$FLASHBACK_DATABASE_LOG view. The amount of flashback data retained in the database is controlled by the initialization parameter and the size of the flash recovery area.