-- show per active transaction the size of the undo and some session information -- more session information can be retrieved by sessinfo2.sql set linesize 250 set pages 50000 column username format a30 column osuser format a30 column machine format a30 column program format a50 column used_undo_mb format 9G999G999D99 column start_date_str format a14 select ses.inst_id, ses.sid, ses.serial#, ses.username, ses.osuser, ses.machine, ses.program, to_char(tra.start_date, 'DD/MM HH24:MI:SS') as start_date_str, tra.used_ublk * 8 / 1024 as used_undo_mb, tra.status from gv$session ses join gv$transaction tra on ( ses.inst_id = tra.inst_id and ses.taddr = tra.addr ) ;