See Also:
An Oracle database is represented to clients as a service, that is, the database performs work on behalf of clients. A database can have one or more services associated with it.
Up to this release, an Oracle database service was uniquely identified by an Oracle System Identifier (SID). The SID was also used internally by the database as pointer to the System Global Area (SGA). Clients connected to a database instance by specifying the SID in the connect descriptor. This naming scheme did not distinguish services from instances.
In Oracle8i, a new naming schema has been implemented. Because an Oracle database can span over multiple computers, both the service as a whole and each of its instances are specified.
A database is now identified by its service
name with the SERVICE_NAMES parameter in the initialization
parameter file. SERVICE_NAMES specifies the name of
the highest-level view of Oracle database service, which may span
instances and/or nodes. SERVICE_NAMES is defaulted to
the global database name, a
name comprised of the database name (DB_NAME) and domain
name (DB_DOMAIN).
Database instances are identified by an instance
name with the INSTANCE_NAME parameter in the initialization
parameter file. INSTANCE_NAME corresponds to the
SID of the instance.
Configure connect descriptors with the SERVICE_NAME
(without an S) parameter to connect to an Oracle8i database.
For example, the following connect descriptor contains the address
of a listener located on sales1-sun listening for
connection requests for a database service called sales.us.acme.com:
sales=
(description=
(address=(protocol=tcp)(host=sales-sun1)(port=1521))
(connect_data=
(service_name=sales.us.acme.com)))
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Create a Net Service Name in a tnsnames.ora File
Optionally, connect
descriptors can be configured with the INSTANCE_NAME
parameter to connect to a particular instance of the database. This
may be necessary if you have an Oracle
Parallel Server with multiple instances.
For example, the connect descriptor below contains the address of a
listener located on sales-sun1 listening for connection
requests for an instance called sales1 associated with
the sales.us.acme.com database:
sales=
(description=
(address=(protocol=tcp)(host=sales-sun1)(port=1521))
(connect_data=
(instance_name=sales1)
(service_name=sales.us.acme.com)))
This is an advanced feature not supported by the Net8 Configuration Assistant.
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See Also: Chapter 8, Enabling Advanced Net8 Features, in the Net8
Administrator's Guide for further information about specifying
an instance name in the |
