This post provides with a script to verify the UNDO usage by active database sessions.
select se.saddr,se.inst_id,se.sid,se.module, sum(tr.used_ublk*8192/1024/1024)"Used(MB)"
from gv$session se, gV$transaction tr
where tr.ses_addr = se.saddr and se.inst_id=tr.inst_id
group by se.saddr,se.module,se.inst_id,se.sid
/
from gv$session se, gV$transaction tr
where tr.ses_addr = se.saddr and se.inst_id=tr.inst_id
group by se.saddr,se.module,se.inst_id,se.sid
/
The Sample Output of the script be like:
