This script can be used to identify a particular Oracle schema size:
select owner, round(sum(bytes)/1024/1024,0) MBytes
from dba_segments
where owner like upper('%&owner%')
and (segment_type like upper('%TABLE%')
or segment_type ='LOBSEGMENT'
or segment_type ='LOB PARTITION')
and segment_name not like 'BIN$%'
group by owner
order by owne
