Oracle service_name tips

Oracle Database Tips by Donald BurlesonFebruary 25, 2015

Question: I want to know what the service_name parameter does in the tnsnames.ora file.

Answer: The the service_name is used to register an instance with the listener. In most all cases, Oracle recommends that the value of the service_name be the same as the ORACLE_SID. However, a service_name can point to more than one instance, and the DBA can gen-in additional ORACLE_SID values into a service_name .

Also see these differences between oracle_sid and service_name.

The service_name is in the tnsnames.ora file to allow you to register an instance with the listener:

mysid=
(DESCRIPTION =
    (ADDRESS =
      (PROTOCOL = TCP)
      (HOST = myserver)
      (PORT = 1521))
   )
   (CONNECT_DATA =
      (SERVICE_NAME = mysid)
   )
)

MOSC Note 68632.1 verifies that the service_name specifies one or more names for the database service to which an instance connects. You can also specify multiple service_name entries in your tnsnames.ora file in order to distinguish among different uses of the same database.

Here is an example if two tnsnames.ora files, one using SID and the other using service_name:

london =
(DESCRIPTION =
     (ADDRESS_LIST =
         (ADDRESS =
           (COMMUNITY = TCP)
           (PROTOCOL = TCP)
          (HOST = 123.45.6789)
           (PORT = 1521)
          )
      )
     (CONNECT_DATA =
        (SERVER=dedicated)
        (SERVICE_NAME = london)
    )

berlin =
(DESCRIPTION =
     (ADDRESS_LIST =
         (ADDRESS =
           (COMMUNITY = TCP)
           (PROTOCOL = TCP)
          (HOST = hun)
           (PORT = 1521)
          )
      )
     (CONNECT_DATA = (SID = kraus))
    )

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