Global Database Name Explained

PURPOSE
This article describes the meaning of the global database name, how to
manipulate this name, as well as the impact of this name in a distributed
database system.

SCOPE & APPLICATION
This document is intended for database administrators and/or database users
who want to review general information about the global database name.

Global Database Name Explained:
===============================

Contents:
———
1. What is a global database name?
2. How to determine the current global database name
3. How to change the global database name
4. Related parameters in the init.ora file
5. Related parameter in the listener.ora file
6. Error Messages
7. Related Documents

1. What is a global database name?
———————————-
The global database name is the unique name of the database. In a distributed
database system (a set of databases stored on multiple computers that typically
appears to applications as a single database) the global database name ensures
that each database is distinct from all other databases in the system. Oracle
forms a database’s global database name by prefixing the database’s network
domain with the individual database’s name. For example: sales.us.oracle.com
and sales.uk.oracle.com.

The global database name defaults to DB_NAME.DB_DOMAIN and this value is marked
at database creation time. If you change the DB_NAME or DB_DOMAIN after the
database has been created, the value for the global database name (GLOBAL_NAME)
will not change.

2. How to determine the current global database name:
—————————————————–
When connected as SYS, you can query the table props$ to find out the value of
the global database name:

SQL> SELECT * FROM props$ WHERE name=’GLOBAL_DB_NAME’;

NAME VALUE$ COMMENT$
—————— ————————- ———————
GLOBAL_DB_NAME TEST815.CH.ORACLE.COM Global database name
1 row selected.

A public view with the name GLOBAL_NAME is available which issues a query on
the table props$. So any user can find out the global database name by querying
this public view:

SQL> SELECT * FROM global_name;

GLOBAL_NAME
———————-
TEST815.CH.ORACLE.COM
1 row selected.

3. How to change the global database name:
——————————————
To change the global database name, issue the following command (renaming the
global database name will not change the value of the DB_NAME or DB_DOMAIN
parameters):

SQL> ALTER DATABASE RENAME GLOBAL_NAME TO remote1.oracle.com;

4. Related parameters in the init.ora file:
————————————————
DB_NAME =
The parameter DB_NAME identifies a specific database on a node and specifies
the prefix component of a global database name, consisting of valid characters
(alphabetic characters, numbers, underscore (_), sharp (#), or dollar ($)) up
to eight characters. The default value is NULL, but generally it should be set
before invoking CREATE DATABASE and then referenced in that statement. Multiple
instances must have the same value.

DB_DOMAIN =
The parameter DB_DOMAIN specifies the extension components of a global
database name, consisting of valid identifiers (alphabetic characters, numbers,
underscore (_), or sharp (#)), separated by periods and up to 128 characters
long. The default value is WORLD and the parameter cannot be NULL. Multiple
instances must have the same value.

GLOBAL_NAMES = [TRUE | FALSE]
The parameter GLOBAL_NAMES specifies whether a database link is required to
have the same name as the global database name to which it connects. If the
value of GLOBAL_NAMES is FALSE, then no check is performed. Oracle recommends
setting this parameter to TRUE to ensure the use of consistent naming
conventions for databases and links. To check the current value of this
parameter, issue the following command:

SQL>SELECT name,value FROM v$parameter WHERE name = ‘global_names’;

NAME VALUE
—————- ——–
global_names TRUE
1 row selected.

You can change the value of this parameter dynamically. This can be done for
the current session only or for the current and all consequent sessions:

SQL> ALTER SESSION SET global_names = TRUE;
SQL> ALTER SYSTEM SET global_names = FALSE;

5. Related parameter in the listener.ora file:
———————————————-
In the LISTENER.ORA file, under the sections SID description, a parameter
GLOBAL_DBNAME can be found. This parameter identifies the database by its
global database name and consists of the name and domain name of the database,
as given in SERVICE_NAMES parameter in the database initialization parameter
file (init.ora).

The value of this parameter is used by the Oracle Intelligent Agent to
determine the service name of the database. Detailed information about this
LISTENER.ORA parameter can be found in Note:97066.1 “How the Intelligent
Agent determines a database service name”.

6. Error Messages:
——————
Some error-messages can also be related to the global database name. See the
following:

Note:19307.1 ORA-02024: database link not found
Note:19366.1 ORA-02084: database name is missing a component

7. Related Documents:
———————
Note:15390.1 How to determine and change db_name or Oracle_SID
Note:1018063.102 ORA-02084 while renaming of GLOBAL_NAME irrespective
of new name
Note:97066.1 How the Intelligent Agent determines a database service name
Note:69725.1 Configuring TNSNAMES.ORA SQLNET.ORA and LISTENER.ORA
in Net8

Oracle Reference
Oracle SQL Reference
Net8 Administrator’s Guide
Oracle Database Administrator’s Guide

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