# Oracle System Identifier (SID)

A name that identifies a specific instance of a running pre-release 8.1 Oracle database. For any database, there is at least one instance referencing the database.

For pre-release 8.1 databases, SID was used to identify the database. The SID was included in the part of the connect descriptor in a tnsnames.ora file, and in the definition of the listener in the listener.ora file. Connect descriptors used by clients to connect to an Oracle8 or Oracle7 database should be configured with the SID parameter.

| See Also:

Database Identification by Service Name Rather than SID