最近生产数据库要修改生产用户的密码，由于用户密码修改，各个库之间创建的dblink就失效了，需要重建。上生产一看dblink还真不少，而且谁建的都有，改起来比较费劲。于是想到可以使用expdp的方式导出所有的dblink，即可获取dblink的创建语句，然后修改原密码再在库上创建就可以了。Oracle 生产环境中的库有两个版本10.2.0.4和11.2.0.3下面分别在10g和11g上做测试Oracle 测试10g：SQL> select * from v$version;
BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi PL/SQL Release 10.2.0.4.0 - Production CORE 10.2.0.4.0 Production TNS for Linux: Version 10.2.0.4.0 - Production NLSRTL Version 10.2.0.4.0 - Production创建dblink到11g数据库SQL> create public database link link_11g connect to system identified by "123456" using "（DESCRIPTION = （ADDRESS = （PROTOCOL = TCP）（HOST = 192.168.56.2）（PORT = 1521）） （CONNECT_DATA = （SERVER = DEDICATED） （SERVICE_NAME = orcl） ） ）";
Database link created. SQL> select * from dual@link_11g;
D - X
col owner for a30 col username for a30 col db_link for a30 col host for a50 set linesize 200 set pagesize 999 select OWNER,DB_LINK,USERNAME,HOST from dba_db_links; OWNER DB_LINK USERNAME HOST ------------------------------ ------------------------------ ------------------------------ -------------------------------------------------- PUBLIC LINK_11G SYSTEM （DESCRIPTION = （ADDRESS = （PROTOCOL = TCP）（HOST = 192.168.56. 2）（PORT = 1521）） （CONNECT_DATA = （SERVER = DEDICATED） （SERVICE_NAME = orcl） ） ）使用expdp导出dblink[oracle@rhel5 ~]$ expdp system/123456 directory=dump dumpfile=dblink.dmp full=y include=db_link Export: Release 10.2.0.4.0 - 64bit Production on Thursday, 10 November, 2016 15:26:02 Copyright （c） 2003, 2007, Oracle. All rights reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options FLASHBACK automatically enabled to preserve database integrity. Starting "SYSTEM"."SYS_EXPORT_FULL_01": system/******** directory=dump dumpfile=dblink.dmp full=y include=db_link Estimate in progress using BLOCKS method... Processing object type DATABASE_EXPORT/SCHEMA/TABLE/TABLE_DATA Total estimation using BLOCKS method: 0 KB Processing object type DATABASE_EXPORT/SCHEMA/DB_LINK Master table "SYSTEM"."SYS_EXPORT_FULL_01" successfully loaded/unloaded ****************************************************************************** Dump file set for SYSTEM.SYS_EXPORT_FULL_01 is: /home/oracle/dblink.dmp Job "SYSTEM"."SYS_EXPORT_FULL_01" successfully completed at 15:26:13使用impdp查看导出的dblink的创建语句[oracle@rhel5 ~]$ impdp system/123456 directory=dump dumpfile=dblink.dmp sqlfile=dblink.sql
Import: Release 10.2.0.4.0 - 64bit Production on Thursday, 10 November, 2016 15:28:31
Copyright （c） 2003, 2007, Oracle. All rights reserved.
Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options Master table "SYSTEM"."SYS_SQL_FILE_FULL_01" successfully loaded/unloaded Starting "SYSTEM"."SYS_SQL_FILE_FULL_01": system/******** directory=dump dumpfile=dblink.dmp sqlfile=dblink.sql Processing object type DATABASE_EXPORT/SCHEMA/DB_LINK Job "SYSTEM"."SYS_SQL_FILE_FULL_01" successfully completed at 15:28:33
[oracle@rhel5 ~]$ cat /home/oracle/dblink.sql -- CONNECT SYSTEM -- new object type path is: DATABASE_EXPORT/SCHEMA/DB_LINK CREATE PUBLIC DATABASE LINK "LINK_11G" CONNECT TO "SYSTEM" IDENTIFIED BY VALUES "0588B5151FD4089DC7B87F64727E740D26" USING "（DESCRIPTION = （ADDRESS = （PROTOCOL = TCP）（HOST = 192.168.56.2）（PORT = 1521）） （CONNECT_DATA = （SERVER = DEDICATED） （SERVICE_NAME = orcl） ） ）";测试11gsys@ORCL>select * from v$version;
BANNER -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production PL/SQL Release 11.2.0.4.0 - Production CORE 11.2.0.4.0 Production TNS for Linux: Version 11.2.0.4.0 - Production NLSRTL Version 11.2.0.4.0 - Production创建dblinkcreate public database link link_10g connect to system identified by "123456" using "（DESCRIPTION = （ADDRESS = （PROTOCOL = TCP）（HOST = 192.168.56.11）（PORT = 1521）） （CONNECT_DATA = （SERVER = DEDICATED） （SERVICE_NAME = mydb） ） ）";
Database link created.
sys@ORCL>select * from dual@link_10g;
DUM --- X
sys@ORCL>select OWNER,DB_LINK,USERNAME,HOST from dba_db_links;
Export: Release 11.2.0.4.0 - Production on Thu Nov 10 15:34:24 2016
Copyright （c） 1982, 2011, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options FLASHBACK automatically enabled to preserve database integrity. Starting "SYSTEM"."SYS_EXPORT_FULL_01": system/******** directory=dump dumpfile=dblink.dmp full=y include=db_link Estimate in progress using BLOCKS method... Total estimation using BLOCKS method: 0 KB Processing object type DATABASE_EXPORT/SCHEMA/DB_LINK Master table "SYSTEM"."SYS_EXPORT_FULL_01" successfully loaded/unloaded ****************************************************************************** Dump file set for SYSTEM.SYS_EXPORT_FULL_01 is: /home/oracle/dblink.dmp Job "SYSTEM"."SYS_EXPORT_FULL_01" successfully completed at Thu Nov 10 15:34:42 2016 elapsed 0 00:00:15使用impdp查看导出的dblink的创建语句[oracle@rhel6 ~]$ impdp system/123456 directory=dump dumpfile=dblink.dmp sqlfile=dblink.sql
Import: Release 11.2.0.4.0 - Production on Thu Nov 10 15:35:38 2016
Copyright （c） 1982, 2011, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options Master table "SYSTEM"."SYS_SQL_FILE_FULL_01" successfully loaded/unloaded Starting "SYSTEM"."SYS_SQL_FILE_FULL_01": system/******** directory=dump dumpfile=dblink.dmp sqlfile=dblink.sql Processing object type DATABASE_EXPORT/SCHEMA/DB_LINK Job "SYSTEM"."SYS_SQL_FILE_FULL_01" successfully completed at Thu Nov 10 15:35:40 2016 elapsed 0 00:00:01
[oracle@rhel6 ~]$ cat /home/oracle/dblink.sql -- CONNECT SYSTEM ALTER SESSION SET EVENTS "10150 TRACE NAME CONTEXT FOREVER, LEVEL 1"; ALTER SESSION SET EVENTS "10904 TRACE NAME CONTEXT FOREVER, LEVEL 1"; ALTER SESSION SET EVENTS "25475 TRACE NAME CONTEXT FOREVER, LEVEL 1"; ALTER SESSION SET EVENTS "10407 TRACE NAME CONTEXT FOREVER, LEVEL 1"; ALTER SESSION SET EVENTS "10851 TRACE NAME CONTEXT FOREVER, LEVEL 1"; ALTER SESSION SET EVENTS "22830 TRACE NAME CONTEXT FOREVER, LEVEL 192 "; -- new object type path: DATABASE_EXPORT/SCHEMA/DB_LINK CREATE PUBLIC DATABASE LINK "LINK_10G" CONNECT TO "SYSTEM" IDENTIFIED BY VALUES ":1" USING "（DESCRIPTION = （ADDRESS = （PROTOCOL = TCP）（HOST = 192.168.56.11）（PORT = 1521）） （CONNECT_DATA = （SERVER = DEDICATED） （SERVICE_NAME = mydb） ） ）"; CREATE PUBLIC DATABASE LINK "LINK_A" CONNECT TO "SCOTT" IDENTIFIED BY VALUES ":1" USING "orcl";使用上面的方式可以查看dblink的创建语句。从上面dblink创建语句的输出结果也可以看出10g导出的dblink创建语句可以看到密码的密文，而11g里就看不到了。官方文档：http://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_5005.htm#i2061505更多Oracle相关信息见Oracle 专题页面 http://www.linuxidc.com/topicnews.aspx？tid=12本文永久更新链接地址
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