select owner, object_name, subobject_name, nb_writes
from ( select owner, object_name, subobject_name, 
              sum(value) nb_writes,
              rank() over (order by sum(value) desc) rk
       from v$segment_statistics
       where statistic_name like 'physical writes%'
         and owner != 'SYS'
       group by owner, object_name, subobject_name 
       having sum(value) > 0 )
where rk <= 50
order by rk
/