A session pool is a number of sessions that are logged onto the Teradata Database server as a unit, using the same logon string via a TDP START POOL command.
Unlike ordinary sessions, pool sessions are automatically assigned to applications that initiate a logon using the same logon string as that established for the pool. Every session in a pool is assigned to a specific PE and stays with that PE until the session ends.
When the pool is established, all sessions are not in use. When an application sends a logon request whose string matches that of the session pool, the application is assigned an available session from the pool.
That session is marked in-use and cannot be reassigned to another application until the current application logs off. Sessions pools remain logged on until you log them off with the STOP POOL or LOGOFF POOL commands.
For more information on session pools and TDP commands, see Teradata Director Program Reference.