通过以下语句直接分析出每个数据库文件可压缩量

 

select a.file#,       a.name,       a.bytes / 1024 / 1024 CurrentMB,       ceil(HWM * a.block_size) / 1024 / 1024 ResizeTo,       (a.bytes - HWM * a.block_size) / 1024 / 1024 ReleaseMB,       'alter database datafile ''' || a.name || ''' resize ' ||       ceil(HWM * a.block_size / 1024 / 1024) || 'M;'||       'alter database datafile ''' || a.name || ''' autoextend on next 100M;'               ResizeCMD  from v$datafile a,       (select file_id, max(block_id + blocks - 1) HWM          from dba_extents         group by file_id) b where a.file# = b.file_id(+)   and (a.bytes - HWM * block_size) > 0 order by 5 desc