Monitoring Index Usage

1. Enable monitoring

ALTER INDEX [index_name] MONITORING USAGE;

2. View the infomation

col owner format a10
col index_name format a20
col monitoring format a10
col used format a6
 select
    u.name "owner",
    io.name "index_name",
--    t.name "table_name",
    decode(bitand(i.flags, 65536), 0, 'no', 'yes') "monitoring",
    decode(bitand(nvl(ou.flags,0), 1), 0, 'no', 'yes') "used",
    ou.start_monitoring "start_monitoring",
    ou.end_monitoring "end_monitoring"
 from
    sys.obj$ io,
    sys.obj$ t,
    sys.ind$ i,
    sys.object_usage ou,
    sys.user$  u
 where
    t.obj# = i.bo#
 and
    io.owner# = u.user#
 and
    io.obj# = i.obj#
 and
    u.name not in ('sys','system')
 and
    i.obj# = ou.obj#(+)
 and t.name='TAB';

Note: v$object_usage has to be queried by connecting as specific schema user.
The above query can show info for indexes under different schema.

3. Check whether the index is monitorred or not

SELECT index_name,
       table_name,
       monitoring,
       used,
       start_monitoring,
       end_monitoring
FROM   v$object_usage
WHERE  index_name = [index_name]
 and   table_name= [table_name];