The Top 25 sessions grid captures Tempdb space usage at the time the last SQL statement for the session completed. This grid is populated from sys.dm_db_file_space_usage.
Session ID
The ID of the session generating Tempdb usage.
Total Space
The total space in Tempdb consumed by this session.
Application
The application generating Tempdb usage.
Host
The name of the Windows server hosting the SQL Server instance.
User
The SQL Server login name for this session.
Current SQL
The SQL statement last completed.
Internal Objects Space
The space consumed by internal objects in all tasks in this session.
User Objects Space
The total space used by user objects in this session.
Note: The Internal Objects Space and User Objects Space represent the (allocated - deallocated) pages during the lifetime of the session. They are counters, rather than instantaneous figures. Page counters are initialized to zero (0) at the start of a session. The counters track the total number of pages that have been allocated or deallocated for tasks that are already completed in the session. The counters are updated only when a task ends; they do not reflect running tasks.