Unloading Data Using the ORACLE_DATAPUMP Access Driver【每日一译】--20121225

To unload data, you use the ORACLE_DATAPUMP access driver. The data stream that is
unloaded is in a proprietary format and contains all the column data for every row
being unloaded.
An unload operation also creates a metadata stream that describes the contents of the
data stream. The information in the metadata stream is required for loading the data
stream. Therefore, the metadata stream is written to the datafile and placed before the

data stream.

为了御载数据，你可以使用ORACLE_DATAPUMP访问驱动器。数据流被御载通过一个专用的

格式并且包含所有列的数据对于每个正在被御载的行。

一个御载操作也创建一个元数据流，它描述了数据流的内容。这个信息在元数据流里被

要求导入数据流。所以元数据流被写入到数据文件和安排好要在数据数据流御载前。