Undo used per session

UNDO used per session:

set pages 100 lines 160

col sid_serial for a20

col orauser for a15

col program for a30

col undoseg for a15

col undo for a10

SELECT TO_CHAR(s.sid)||','||TO_CHAR(s.serial#) sid_serial,

NVL(s.username, 'None') orauser,

s.program,

r.name undoseg,

t.used_ublk * TO_NUMBER(x.value)/1024||'K' "Undo"

FROM sys.v_$rollname r,

sys.v_$session s,

sys.v_$transaction t,

sys.v_$parameter x

WHERE s.taddr = t.addr

AND r.usn = t.xidusn(+)

AND x.name = 'db_block_size';