708. You executed the following query:
Considering that all the redo logs are available, what information can you derive from the output of the
preceding query?
A.The time when the last flashback operation in your database was performed
B.The time when the first flashback operation in your database was performed
C.The approximate time and the lowest system change number (SCN) to which you can flashback your database
D.The system change number (SCN) and the time when the Flashback Database was enabled in the
database instance
Answer: C
答案解析：
题中问：考虑到所有的重做日志可用，什么样的信息可以来自上述查询的输出？
V$FLASHBACK_DATABASE_LOG
V$FLASHBACK_DATABASE_LOG displays information about the flashback data. Use this view to help estimate the amount of flashback space required for the current workload.
| Column | Datatype | Description |
|---|---|---|
OLDEST_FLASHBACK_SCN |
NUMBER |
Lowest system change number (SCN) in the flashback data, for any incarnation |
OLDEST_FLASHBACK_TIME |
DATE |
Time of the lowest SCN in the flashback data, for any incarnation |
RETENTION_TARGET |
NUMBER |
Target retention time (in minutes) |
FLASHBACK_SIZE |
NUMBER |
Current size (in bytes) of the flashback data |
ESTIMATED_FLASHBACK_SIZE |
NUMBER |
Estimated size of flashback data needed for the current target retention |