col	owner format a15
col	segment_name format a30
col	segment_type format a15
col	mb format 999,999,999
select  owner
,	segment_name
,	segment_type
,	mb
from	(
	select	owner
	,	segment_name
	,	segment_type
	,	bytes / 1024 / 1024 "MB"
	from	dba_segments
	order	by bytes desc
	)
where	rownum < 11
/