Instance-Specific Information can be stored in the server data dictionary. The instance name, FDS_INST_NAME, is configured by the database administrator (DBA) who administers the agent. How the DBA performs this configuration depends on the specific agent in use.
The Oracle database server uses FDS_INST_NAME to look up instance-specific configuration information in its data dictionary. Oracle uses the value as a primary key for columns of the same name in these views:
FDS_INST_INIT
FDS_INST_CAPS
FDS_INST_DD
Server data dictionary accesses that use FDS_INST_NAME also use FDS_CLASS_NAME to uniquely identify configuration information rows. For example, if you port a database from class Sybase816 to class Sybase817, both databases can simultaneously operate with instance name SCOTT and use separate sets of configuration information.
Unlike class information, instance information is not automatically self-registered in the server data dictionary:
If available, instance information is always uploaded by the agent. However, it is never stored in the server data dictionary. Instead, the information is kept in memory and it is only valid for that connection.
If the server data dictionary contains instance information, it represents the DBA's defined setup details which correspond to the instance configuration. Data dictionary defined instance information takes precedence over class information. However, uploaded instance information takes precedence over data dictionary defined instance information.