create database links

Re-create database links : -

To check for the existence of database links, use SQL*Plus on the database server node to connect to the Applications database instance as APPS and run the following query:

$ sqlplus apps/
SQL> select db_link from dba_db_links; 

If the EDW_APPS_TO_WH and APPS_TO_APPS database links exist, use the following commands to drop and re-create them:

$ sqlplus apps/
SQL> alter session set global_names=false;
SQL> drop database link EDW_APPS_TO_WH;
SQL> drop database link APPS_TO_APPS;

SQL> create database link EDW_APPS_TO_WH connect to apps
     identified by  using
     '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=)
     (PORT=))(CONNECT_DATA=(SID=)))';

SQL> create database link APPS_TO_APPS connect to apps
     identified by  using
      '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=)
     (PORT=))(CONNECT_DATA=(SID=)))';

where is the host name of the database server node, is the port number of the new Net8 listener for the database instance, and is the ORACLE_SID of the database instance. If you have custom self-referential database links in the database instance, use the following commands to drop and re-create them:

$ sqlplus apps/
SQL> drop database link ;
SQL> create database link  connect to
      identified by  using
     '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=)
     (PORT=))(CONNECT_DATA=(SID=)))';

where , , , and are all as they were in the original database link definition, and is the port number of the new Net8 listener for the database instance.