DB_DOMAIN

Parameter type	String
Syntax	DB_DOMAIN = domain_name
Default value	There is no default value.
Parameter class	Static
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.
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, separated by periods. Oracle Corporation 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 (#).

See Also: Oracle9i Database Performance Tuning Guide and Reference for more information on setting this parameter The data dictionary view "GLOBAL_NAME"