incase you cannot do imp/export due to a 24/7 OLTP database . column file_name format
a50; column tablespace_name format a15; column highwater format 9999999999; set pagesize 9999 select a.tablespace_name ,a.file_name ,(b.maximum+c.blocks-1)*d.db_block_size highwater from dba_data_files a ,(select file_id,max(block_id) maximum from dba_extents group by file_id) b ,dba_extents c ...