A clone database is a specialized copy of a database that can be used for tablespace
point-in-time recovery. When you perform tablespace point-in-time recovery, you
mount the clone database and recover the tablespaces to the desired time, then export
metadata from the clone to the primary database and copy the datafiles from the
recovered tablespaces.

克隆数据库如何装载
1. 克隆数据库可用于按时间点恢复
2. 当用户按时间点恢复表空间时,需要将克隆数据库装载 , 将其中的表空间恢复到期望的时间,
然后将克隆数据库中被恢复的表空间的元数据及数据文件复制到主数据库