Your DB_RECOVERY_FILE_DEST_SIZE IS 8G,Currently,5G of the space is used of which 4G consists of obsolete backups, You execute this command;
SQL> ALTER SYSTEM SET db_recovery_file_dest_size=2G;
What is the outcome?
A) It changes DB_RECOVERY_FILE_DEST_SIZE to 2G and deletes the obsolete backups
B) It changes DB_RECOVERY_FILE_DEST_SIZE to 5G
C) It fails because DB_RECOVERY_FILE_DEST_SIZE is a static parameter
D) It changes DB_RECOVERY_FILE_DEST_SIZE to 2G without deleting valid backups
E) It fails because the new size is less than 5G
Answer: D (验证过)
CUUG：因为当前还有空闲的空间 3G,所以无需删除有效和无效的备份。
赵：网友选 A 待验证。个人认为有效的备份只有 1G，小于被修改后的 2G，不需要删除过时的备份。
题译：DB_Recovery_file_DEST_size 为 8G，目前使用的空间为 5G，其中 4G 由过时的备份组成。
其他：A 实测不会删除