A. It cannot be done in parallel.
B. It can be done at the table level or partition level.
C. It does not require additional storage because the operation is done online.
D. Local and global indexes are maintained automatically during the operation.
答案：（B）
解析：
参考《SecureFiles and Large Objects Developer's Guide》 4.7.2
联机重定义是将BasicFiles LOBs移植为SecureFiles LOBs唯一建议的方法. 可以在表或分区层次执行.
联机重定义好处：
不需要使表或分区脱机
可以并行执行