oracle 收缩表空间和数据文件，压缩表

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;' 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

begin
execute immediate 'alter table table_name enable row movement';
execute immediate 'alter table table_name shrink space';
execute immediate 'alter table table_name enable row movement';
execute immediate 'alter table table_name shrink space';
execute immediate 'alter table table_name enable row movement';
execute immediate 'alter table table_name shrink space';
end;