Oracle Database Discussions

Could anybody tell me if I understand the DB_UNIQUE_NAME parameter correctly ?

1) Could be used anytime, but useful generally in dataguard, replication.

2) Theorethically must be set when the global name (DB_NAME+DB_DOMAIN) are the same, but must be always set in dataguard, replication.


Could anybody explain me the following behaviour ? Why the global name is not equal to DB_NAME+DB_DOMAIN ?


SQL> show parameter db_name

NAME TYPE VALUE
------------------------------------ ----------- -----------------
db_name string myDB
SQL> show parameter db_domain

NAME TYPE VALUE
------------------------------------ ----------- -----------------
db_domain string DGTI.fr
SQL>
SQL> select * from global_name;

GLOBAL_NAME
------------------------------------------------------------------
MYDB



SQL> select * from v$version;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE 10.2.0.1.0 Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production



Thanks