The OC session database consists of two tables: an OcSession table and an OcClientHost table.
The OcSession table, keyed by a Diameter Session-Id, a long string that is defined by Diameter to be "globally and eternally unique" is used to store the session state info for a session. A subscriber Id is used to look up all sessions associated with the subscriber for session report. An OCS Id references another OC server table for the OCS servers that the sessions may be routed to. Each OcSession table also has a CTF Id referencing the OcClientHost table where the data of OC client host (i.e. FQDN) and OC client realm is stored.