053-128

You want to track and store all transactional changes to a table over its lifetime. To accomplish this
task, you enabled Flashback Data Archive with the retention of 5 years. After some time, the business requirement changed and you were asked to change the retention from 5 years to 3 years. To accomplish this, you issued the following command:
ALTER FLASHBACK ARCHIVE fla1 MODIFY RETENTION 3 YEAR;
What is the implication of this command?
A. The command produces an error because the retention time cannot be reduced.
B. All historical data is retained but the subsequent flashback data archives are maintained for only three years.
C. All historical data is purged and the new flashback data archives are maintained for three years.
D. All historical data older than three years is purged from the flashback archive FLA1.

　　此题考点是闪回数据归档。在启用闪回数据归档后可以使用 alter 命令修改保留时间。超过保留时间的所有历史数据被清理。