file_high_watermark_segment.sql

select e.file_id,e.owner,e.segment_type,e.segment_name,
       (e.block_id+e.blocks-1)*d.db_block_size/1024/1024 highwater
from dba_extents e,
     (select value db_block_size          
      from v$parameter          
      where name='db_block_size') d 
where (e.file_id,e.block_id) in (select file_id,max(block_id) from dba_extents group by file_id);