Find sessions generating lot of redo in Oracle

Check the sessions generating lot of redo logs

col MODULE for a25
select s.sid,sn.SERIAL#,n.name, round(value/1024/1024,2) redo_mb, sn.username,sn.status,substr (sn.program,1,21)
"program", sn.type, sn.module,sn.sql_id
from v$sesstat s join v$statname n on n.statistic# = s.statistic#
join v$session sn on sn.sid = s.sid where n.name like 'redo size' and s.value!=0 order by
redo_mb desc;


Check the block changed by session

SELECT s.sid, s.serial#, s.username, s.program,i.block_changes
FROM v$session s, v$sess_io i
WHERE s.sid = i.sid
ORDER BY 5 desc

Note:
COLUMN BLOCK_CHANGES which indicates how much blocks have been changed by the session.
High values means session generating lots of redo.