Data Dictionary View
Columns ___________________________ ADDR CR_CHANGE CR_GET DSCN-B DSCN-W FLAG LOG_IO NAME NOUNDO PHY_IO PRV_XIDSLT PRV_XIDSQN PRV_XIDUSN PTX PTX_XIDSLT PTX_XIDSQN PTX_XIDUSN RECURSIVE SES_ADDR SPACE START_SCNB START_SCNW START_TIME START_UBABLK START_UBAFIL START_UBAREC START_UBASQN START_UEXT STATUS UBABLK UBAFIL UBAREC UBASQN USED_UBLK (UNDO Blocks) USED_UREC (UNDO records) XIDSLOT XIDSQN XIDUSN
List the Undo per session
SELECT
s.sid,
s.username,
r.name "RBS name",
tx.start_time,
tx.used_ublk "Undo blocks",
tx.used_urec "Undo recs"
FROM
v$session s,
v$transaction tx,
v$rollname r
WHERE
tx.addr = s.taddr and
r.usn = tx.xidusn;
Related:
V$SESSION
V$ROLLNAME.usn = v$transaction.xidusn