This query shows SID, username and start time of the running transaction.
In addition, number of the used blocks is shown.


SELECT a.sid, a.status, a.username, b.xidusn, b.used_urec, b.used_ublk, b.START_TIME
FROM v$session a, v$transaction b
WHERE a.saddr = b.ses_addr
order by START_TIME desc;