|Oracle® Database Reference
11g Release 2 (11.2)
Part Number E17110-04
|Default value||Derived: (1.5 *
|Range of values||1 to 231|
SESSIONS specifies the maximum number of sessions that can be created in the system. Because every login requires a session, this parameter effectively determines the maximum number of concurrent users in the system. You should always set this parameter explicitly to a value equivalent to your estimate of the maximum number of concurrent users, plus the number of background processes, plus approximately 10% for recursive sessions.
Oracle uses the default value of this parameter as its minimum. Values between 1 and the default do not trigger errors, but Oracle ignores them and uses the default instead.
The default values of the
TRANSACTIONS parameters are derived from
SESSIONS. Therefore, if you increase the value of
SESSIONS, you should consider whether to adjust the values of
TRANSACTIONS as well. (Note that
ENQUEUE_RESOURCES is obsolete as of Oracle Database 10g release 2 (10.2).)
In a shared server environment, the value of
PROCESSES can be quite small. Therefore, Oracle recommends that you adjust the value of
SESSIONS to approximately 1.1 * total number of connections.
Oracle Database Concepts for more information on memory structures and processes