General Information
Purpose	Upgrades all database links, this will simply execute the DDL as the owner of the database link. This needs to be in the migrate mode and the current user executing this should be SYSDBA user.
Source	$ORACLE_HOME/rdbms/admin/dbmslink.sql
Dependencies	DBMS_DBLINK_LIB
Security Model	Can be executed only by a SYSDBA: Granted to execute_catalog_role
UPGRADE
Upgrades all database links, this will simply execute the DDL as the owner of the database link. This needs to be in the migrate mode and the current user executing this should be SYSDBA user.	dbms_dblink.upgrade;
	exec dbms_dblink.upgrade;