DB_DOMAIN

Property	Description
Parameter type	String
Syntax	DB_DOMAIN = domain_name
Default value	There is no default value.
Modifiable	No
Range of values	Any legal string of name components, separated by periods and up to 128 characters long (including the periods). This value cannot be NULL.
Basic	Yes
Real Application Clusters	You must set this parameter for every instance, and multiple instances must have the same value.

In a distributed database system, DB_DOMAIN specifies the logical location of the database within the network structure. You should set this parameter if this database is or ever will be part of a distributed system. The value consists of the extension components of a global database name, consisting of valid identifiers (any alphanumeric ASCII characters), separated by periods. Oracle recommends that you specify DB_DOMAIN as a unique string for all databases in a domain.

This parameter allows one department to create a database without worrying that it might have the same name as a database created by another department. If one sales department's DB_DOMAIN is JAPAN.ACME.COM, then their SALES database (SALES.JAPAN.ACME.COM) is uniquely distinguished from another database with DB_NAME = SALES but with DB_DOMAIN = US.ACME.COM.

If you omit the domains from the name of a database link, Oracle expands the name by qualifying the database with the domain of your local database as it currently exists in the data dictionary, and then stores the link name in the data dictionary. The characters valid in a database domain name are: alphanumeric characters, underscore (_), and number sign (#).

Note:

1. Once a database has been created the GLOBAL_NAME is set in the dictionary and can be checked thus:

SELECT * from GLOBAL_NAME;

To change a database global name use the command:

ALTER DATABASE RENAME GLOBAL_NAME TO ......

2. Query for the current value of the parameter

select name, value, isdefault, isses_modifiable, issys_modifiable,

isinstance_modifiable, isdeprecated, description

from v$parameter where upper(name) = ‘DB_DOMAIN’;

NAME	VALUE	IS DEFAULT	ISSES_ MODIFIABLE	ISSYS_ MODIFIABLE	ISINSTANCE_ MODIFIABLE	IS DEPRECATED	DESCRIPTION
db_domain	mydb.com	FALSE	FALSE	FALSE	FALSE	FALSE	directory part of global database name stored with CREATE DATABASE

Oracle initializatoin parameters