question no: 144
after running the configure retention policy to recovery window of 7 days command, what has been accomplished?
a. retain the data file backup for 7 days.
b. run the recover process every 7 days.
c. destroy the physical backup files every 7 days.
d. destroy the physical backup files older than 7 days.
e. retain one backup of each data file for at least 7 days.
f. keep the catalog information in the control file for 7 days.

答案是 e，
请问a，e 有什么区别吗？

解答:

如果在 7 天?冗??]有新的?浞荩?那?N即使?f的?浞菀殉??^ 7 天，但仍然??是要保留的。?@就是  a ?c e 的不同之??。

答案是e
a是?f db 的datafile
e是?f backup set 的datafile
retention policy  是定?xbackup保存的?r?g 所以答案是e