关于oracle 11g 数据库回滚racle 9i的问题

升级数据库的方法有很多，最基础的就是exp/imp方法。

当然，从安全角度上说，DBUA是最好的。

回滚时，也可以用exp/imp方法。
但从11g回滚到9i就不一定可以用了。
原因就是Oracle 9.2的imp工具不能正确识别11g导出数据的Segmentation。
这时我的解决 方法，就是先把11g的数据导到10g的DB中，
再从10gDB中将数据导出，在9.2DB中导入这些数据。
用来保证业务的安全。
Oracle 8i以后各个版本导入的支持列表：

+-----------+------------------------------------------------------------------------------------+
|  EXPORT   |                              IMPORT into:                                          |
|   from    +--------+--------+--------+--------+--------+---------+---------+---------+---------+
|    \/     |  8.1.5 |  8.1.6 |  8.1.7 |  9.0.1 |  9.2.0 | 10.1.0  | 10.2.0  | 11.1.0  | 11.2.0  |
+-----------+--------+--------+--------+--------+--------+---------+---------+---------+---------+
|  5.x 1) 2)| EXP5x  | EXP5x  | EXP5x  | EXP5x  | EXP5x  | EXP5x   | EXP5x   | EXP5x   | EXP5x   |
|  6.x    2)| EXP6x  | EXP6x  | EXP6x  | EXP6x  | EXP6x  | EXP6x   | EXP6x   | EXP6x   | EXP6x   |
|  7.x    3)| EXP7x  | EXP7x  | EXP7x  | EXP7x  | EXP7x  | EXP7x   | EXP7x   | EXP7x   | EXP7x   |
+-----------+--------+--------+--------+--------+--------+---------+---------+---------+---------+
|  8.0.3    | EXP803 | EXP803 | EXP803 | EXP803 | EXP803 | EXP803  | EXP803  | EXP803  | EXP803  |
|  8.0.4    | EXP804 | EXP804 | EXP804 | EXP804 | EXP804 | EXP804  | EXP804  | EXP804  | EXP804  |
|  8.0.5    | EXP805 | EXP805 | EXP805 | EXP805 | EXP805 | EXP805  | EXP805  | EXP805  | EXP805  |
|  8.0.6    | EXP806 | EXP806 | EXP806 | EXP806 | EXP806 | EXP806  | EXP806  | EXP806  | EXP806  |
+-----------+--------+--------+--------+--------+--------+---------+---------+---------+---------+
|  8.1.5    | EXP815 | EXP815 | EXP815 | EXP815 | EXP815 | EXP815  | EXP815  | EXP815  | EXP815  |
|  8.1.6    | EXP815 | EXP816 | EXP816 | EXP816 | EXP816 | EXP816  | EXP816  | EXP816  | EXP816  |
|  8.1.7    | EXP815 | EXP816 | EXP817 | EXP817 | EXP817 | EXP817  | EXP817  | EXP817  | EXP817  |
+-----------+--------+--------+--------+--------+--------+---------+---------+---------+---------+
|  9.0.1    |   N/S  | EXP816 | EXP817 | EXP901 | EXP901 | EXP901  | EXP901  | EXP901  | EXP901  |
|  9.2.0    |   N/S  |   N/S  | EXP817 | EXP901 | EXP920 | EXP920  | EXP920  | EXP920  | EXP920  |
+-----------+--------+--------+--------+--------+--------+---------+---------+---------+---------+
| 10.1.0  4)|  Not Supported  | EXP817 | EXP901 | EXP920 |                   4)                  |
| 10.2.0  4)|  Not Supported  | EXP817 | EXP901 | EXP920 |                   4)                  |
+-----------+--------+--------+--------+--------+--------+---------+---------+---------+---------+
| 11.1.0  4)|           Not Supported           |   5)   |                   4)                  |
| 11.2.0  4)|           Not Supported           |   5)   |                   4)                  |
+-----------+--------+--------+--------+--------+--------+---------+---------+---------+---------+

Oracle 8i以前版本对imp的支持情况

+-----------+--------------------------------------------------------------+
|  EXPORT   |                       IMPORT into:                           |
|   from    +--------+--------+--------+--------+--------+--------+--------+
|    \/     |   5.x  |   6.x  |  7.0.x |  7.1.x |  7.2.x |  7.3.x |  8.0.x |
+-----------+--------+--------+--------+--------+--------+--------+--------+
|  5.x 1) 2)| EXP5x  | EXP5x  | EXP5x  | EXP5x  | EXP5x  | EXP5x  | EXP5x  |
|  6.x    2)|  N/S   | EXP6x  | EXP6x  | EXP6x  | EXP6x  | EXP6x  | EXP6x  |
+-----------+--------+--------+--------+--------+--------+--------+--------+
|  7.0.x  3)|  N/S   | EXP6x  | EXP70x | EXP70x | EXP70x | EXP70x | EXP70x |
|  7.1.x  3)|  N/S   | EXP6x  | EXP70x | EXP71x | EXP71x | EXP71x | EXP71x |
|  7.2.x  3)|  N/S   | EXP6x  | EXP70x | EXP71x | EXP72x | EXP72x | EXP72x |
|  7.3.x  3)|  N/S   | EXP6x  | EXP70x | EXP71x | EXP72x | EXP73x | EXP73x |
+-----------+--------+--------+--------+--------+--------+--------+--------+
|  8.0.x  4)|  Not Supported  | EXP70x | EXP71x | EXP72x | EXP73x | EXP80x |
|  8.1.x  4)|  Not Supported  | EXP70x | EXP71x | EXP72x | EXP73x | EXP80x |
+-----------+--------+--------+--------+--------+--------+--------+--------+
|  9.0.1.x  |                    Not Supported                    |    5)  |
|  9.2.0.x  |                    Not Supported                    |    5)  |
+-----------+--------+--------+--------+--------+--------+--------+--------+
| 10.1.0.x  |                         Not Supported                        |
| 10.2.0.x  |                         Not Supported                        |
+-----------+--------+--------+--------+--------+--------+--------+--------+
| 11.1.0.x  |                         Not Supported                        |
| 11.2.0.x  |                         Not Supported                        |
+-----------+--------+--------+--------+--------+--------+--------+--------+