实验环境：
服务器A：172.21.1.30
服务器B：172.21.1.40
两台服务器上分别运行两套oracle数据库，本实验以scott用户为例进行测试。
实验目的：
通过DB_LINK的复制功能，利用expdp,impdp进行数据的远程备份及恢复。
进行测试前，将服务器B上scott用户的dept,emp进行删除，本测试只是使用
impdp将服务器A数据库下scott用户的dept,emp表导入到服务器B数据库
scott用户下。
操作步骤：
1.在服务器A，B上分别以sys身份登录数据库，并创建directory,db_link,命令如下：
session A: > create directory dp01 as '/bk/dp01';
Directory created.
session A: >create public database link ln_db40 connect to scott identified by tiger using 'ip40';
Database link created.
session A: >grant connect,resource,exp_full_database,imp_full_database to scott identified by tiger;
Grant succeeded.
session B: > create directory dp02 as '/bk/dp02';
Directory created.
session B: >create public database link ln_db30 connect to scott identified by tiger using 'ip30';
Database link created.
session B: >grant connect,resource,exp_full_database,imp_full_database to scott identified by tiger;
Grant succeeded.
2.在确认以上步骤中的db_link没问题后，做以下操作：
a. 服务器A：(将本地数据库中scott用户下的dept,emp两张表导出备份文件为exp01.dmp)
[oracle@session A: dp01]$ expdp scott/tiger directory=dp01 dumpfile=exp01.dmp network_link=ln_db30 tables=emp,dept
Export: Release 10.2.0.1.0 - Production on Wednesday, 03 August, 2011 14:39:05
Copyright (c) 2003, 2005, Oracle. All rights reserved.
Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Starting "SCOTT"."SYS_EXPORT_SCHEMA_01": scott/********@ip30 directory=dp01 dumpfile=exp01.dmp network_link=ln_db30 tables=emp,dept
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 320 KB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
. . exported "SCOTT"."SYS_EXPORT_SCHEMA_01" 172.8 KB 1073 rows
. . exported "SCOTT"."DEPT" 5.656 KB 4 rows
. . exported "SCOTT"."EMP" 7.820 KB 14 rows
Master table "SCOTT"."SYS_EXPORT_SCHEMA_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SCOTT.SYS_EXPORT_SCHEMA_01 is:
/bk/dp01/exp01.dmp
Job "SCOTT"."SYS_EXPORT_SCHEMA_01" successfully completed at 14:39:37
[oracle@session A: dp01]$ ls
exp01.dmp export.log import.log
b. 将备份文件exp01.dmp从服务器A拷贝到服务器B：
[oracle@session A: dp01]$ scp –r exp01.dmp 172.21.1.40:/bk/dp02/
c.在服务器A上，执行以下命令，将dept,emp表导入到服务器B的scott用户下：
[oracle@session A: dp01]$ impdp scott/tiger@ip40 directory=dp02 dumpfile=exp01.dmp tables=emp,deptImport: Release 10.2.0.1.0 - Production on Wednesday, 03 August, 2011 14:34:57
Copyright (c) 2003, 2005, Oracle. All rights reserved.
Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Master table "SCOTT"."SYS_IMPORT_TABLE_01" successfully loaded/unloaded
Starting "SCOTT"."SYS_IMPORT_TABLE_01": scott/********@ip40 directory=dp02 dumpfile=exp01.dmp tables=emp,dept
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
. . imported "SCOTT"."DEPT" 5.656 KB 4 rows
. . imported "SCOTT"."EMP" 7.820 KB 14 rows
Processing object type TABLE_EXPORT/TABLE/INDEX/INDEX
Processing object type TABLE_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type TABLE_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Job "SCOTT"."SYS_IMPORT_TABLE_01" successfully completed at 14:34:55
3.使用sys用户登录服务器A的数据库，进行测试，查看B的scott用户下的dept,emp表是否存在：
$ sqlplus / as sysdba
session A: > conn scott/tiger
Connected.
session A: > select * from tab;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
DEPT TABLE
EMP TABLE
session A: > select * from tab@ln_db40;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
DEPT TABLE
EMP TABLE
由以上实验不难看出，表dept,emp已成功导入B的scott用户。
EXPDP 可以导出所有数据库的数据，只要它能连接到这个数据库，或者它登录的数据库
上能读取到被导出的库的数据，因为此时可以通过数据库链来读取被导出的库的数据。
如下测试：
可以分为三个服务器：A，B，C，以下命令在A在执行：
[oracle@session A: dp01]$ expdp scott/tiger@ip40 directory=dp02 dumpfile=exp01.dmp network_link=ln_db50 tables=emp,dept
Export: Release 10.2.0.1.0 - Production on Wednesday, 03 August, 2011 14:39:05
Copyright (c) 2003, 2005, Oracle. All rights reserved.
Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Starting "SCOTT"."SYS_EXPORT_SCHEMA_01": scott/********@ip40 directory=dp02 dumpfile=exp01.dmp network_link=ln_db50 tables=emp,dept
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 320 KB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
. . exported "SCOTT"."SYS_EXPORT_SCHEMA_01" 172.8 KB 1073 rows
. . exported "SCOTT"."DEPT" 5.656 KB 4 rows
. . exported "SCOTT"."EMP" 7.820 KB 14 rows
Master table "SCOTT"."SYS_EXPORT_SCHEMA_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SCOTT.SYS_EXPORT_SCHEMA_01 is:
/bk/dp01/exp01.dmp
Job "SCOTT"."SYS_EXPORT_SCHEMA_01" successfully completed at 14:39:37
说明：
expdp 在服务器A上；
scott/tiger@ip40 连接到服务器B的数据库；
network_link=ln_db30 是服务器B的数据库中scott用户的数据库链，其指向服务器C的用户scott，
SCOTT10用户中只有两个表dept,emp.
从上面的操作可以看出：expdp 可以是客户端的程序，但它导出的数据（DMP）必须存放在它登录
的数据库的目录下（本例中，存放在机器B的数据库directory=dp02下），而被导出的数据是通过
数据库链(network_link)到机器C的数据库里读取的。
另外注意：在这过程中,A数据库用户scott和C数据库用户scott（或者数据库链中的用户）都必须被
授予EXP_FULL_DATABASE 权限。
nelwork_link意思是从本地数据库导入datafile直接到remote database,中间省略了exp的操作,
nelwork_link=source_database_link,确认nelwork_link参数是一个存在的目标数据库名称,同时
存在database link.
补充一下两个限制条件：
nelwork_link parameter Restrictions
Network imports do not support the use of evolved types.
a: When the NETWORK_LINK parameter is used in conjunction with the TABLES parameter,
only whole tables can be imported (not partitions of tables).
所以，当使用impdp导入时多张表时，如果添加network_link参数，就会报错如下：
UDI-00011: parameter dumpfile is incompatible with parameter network_link
b: If the USERID that is executing the import job has the IMP_FULL_DATABASE role on the
target database, then that user must also have the EXP_FULL_DATABASE role on the source
database.The only types of database links supported by Data Pump Import are: public,
fixed-user, and connected-user. Current-user database links are not supported.
本文转自vcdog 51CTO博客，原文链接：http://blog.51cto.com/255361/837646，如需转载请自行联系原作者
