For every user using temporary space, there is an entry in
SYS.V$_LOCK with type 'TS'.
All temporary segments are named 'ffff.bbbb' where 'ffff' is the file it is
in and 'bbbb' is first block of the segment. If your temporary
tablespace is set to TEMPORARY, all sorts are done in one large
temporary segment. For usage stats, see SYS.V_$SORT_SEGMENT
From Oracle 8.0, one can just query SYS.v$sort_usage. Look at these