RMAN 只备份当前数据？ 正解如下。

下面这句将说明RMAN 到底备份那些资料。

Data file backup sets do not include empty blocks. An empty block is a block that has never contained data. If a block has been used, but is no longer part of an allocated extent, then it is still backed up because the backup process does not have access to space management information. This is a source of some confusion because some users think that RMAN will omit blocks that do not currently contain data. For example, if a table is dropped, then RMAN will continue to back up the blocks even though the extents that are used by that table are now free.