標籤：
先看oracle 10g的官方文檔：
Database Utilities
Data Performance Improvements for Data Pump Export and Import
The improved performance of the Data Pump Export and Import utilities is attributable to several factors, including the following:
Multiple worker processes can perform intertable and interpartition parallelism to load and unload tables in multiple, parallel, direct-path streams.
--多個進程並行和直接路徑讀
For very large tables and partitions, single worker processes can choose intrapartition parallelism through multiple parallel queries and parallel DML I/O server processes when the external tables method is used to access data.
Data Pump uses parallelism to build indexes and load package bodies.
--可以並行的建索引和包
Dump files are read and written directly by the server and, therefore, do not require any data movement to the client.
--在伺服器上操作，不需要將資料返回給用戶端，省去網路的環節
The dump file storage format is the internal stream format of the direct path API. This format is very similar to the format stored in Oracle database datafiles inside of tablespaces. Therefore, no client-side conversion to INSERT statement bind variables is performed.
--匯出的資料檔案是block格式，不是exp的SQL語句
The supported data access methods, direct path and external tables, are faster than conventional SQL. The direct path API provides the fastest single-stream performance. The external tables feature makes efficient use of the parallel queries and parallel DML capabilities of the Oracle database.
--支援直接路徑讀，比轉換成SQL快
Metadata and data extraction can be overlapped during export.
--中繼資料和資料的提取可以同時執行
翻譯的不好，總結如下：
1.expdp是服務端程式，exp是用戶端程式，exp還需要網路傳輸，這個很影響速度。
2.expdp讀的就是資料區塊，exp是要轉換成SQL。
3.expdp可以並行匯出資料、中繼資料和建索引、包，exp不行。
4.expdp採用的是直接路徑讀，exp是要通過SGA。
Oracle expdp為什麼比exp快，原理是什麼
