To Find Top List Segments Usage...

Total list
========
select SEGMENT_NAME "Table Name",sum(BLOCKS)  "Total blocks" ,
sum(bytes/1024/1024) "Size in MB" from dba_segments
where segment_name like 'MLOG$%'
group by segment_name
 order by 2 desc;

Top-20 list
=========
select * from (
select SEGMENT_NAME "Table Name",sum(BLOCKS)  "Total blocks" ,
sum(bytes/1024/1024) "Size in MB" from dba_segments
where segment_name like 'MLOG$%'
group by segment_name
 order by 2 desc)
where rownum < 20