With respect to session pooling (having a pool of pre-logged on sessions), whenever an application transmits a logon request using a logon string that matches one in the established session pool, the application is assigned to one of the available sessions.
Assigning an application to an established session pool improves response time since the application’s logon request need not be sent to the database. Once a transaction starts, subsequent calls to the database use the pre-allocated sessions instead of repeating the logon procedure.
The transaction’s logon entry in the session pool exists until the program issues a LOGOFF request to the database.
Then, all resources allocated to the transaction are released and returned to the session pool.
For more information on session pooling, see Teradata® Director Program Reference, B035-2416.