To start monitoring the index usage:
ALTER INDEX
To stop:
ALTER INDEX
To monitor the status if you can login as owner then use
select * from v$object_usage;
If viewing the stats as other/super user then use below:
select d.username, io.name INDEX_NAME, t.name TABLE_NAME,
decode(bitand(i.flags, 65536), 0, 'NO', 'YES') MONITORING,
decode(bitand(ou.flags, 1), 0, 'NO', 'YES') INDEX_USED,
ou.start_monitoring,
ou.end_monitoring
from sys.obj$ io, sys.obj$ t, sys.ind$ i, sys.object_usage ou,
dba_users d
where io.owner# = d.user_id
AND d.username = 'CN'
and i.obj# = ou.obj#
and io.obj# = ou.obj#
and t.obj# = i.bo#;
Ex:-
