我們來看一下如何收縮表空間，其實方法很簡單。首先我們先計算datafile可以resize收縮的空間.
col name for a40
col resizecmd for a80
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$datafile a,
(select file_id,max(block_id+blocks-1) HWM
from dba_extents
group by file_id) b
where a.file# = b.file_id(+)
and (a.bytes - HWM *block_size)>0
order by 5
如果只是想對某個表個間的datafile resize,可采用:
select a.file#,a.name,a.bytes/1024/1024 CurrentMB,
ceil(HWM * a.block_size)/1024/1024 ResizeTo,
(a.bytes - HWM * a.block_size)/1024/1024 ReleaseMB,
'alter database datafile '''||a.name||''' resize '||
ceil(HWM * a.block_size/1024/1024) || 'M;' ResizeCMD
from v$datafile a,
(select file_id,max(block_id+blocks-1) HWM
from dba_extents where file_id in
(select b.file# From v$tablespace a ,v$datafile b
where a.ts#=b.ts# and a.name='MP2000')
group by file_id) b
where a.file# = b.file_id(+)
and (a.bytes - HWM *block_size)>0
order by 5
計劃tempfile可以resize的空間.on apply that have only one tempfile
select 'alter database tempfile '''||a.name ||''' reize '||b.siz||'M;' from v$tempfile a,
(select tmsize.maxblk*bk.value/1024/1024 siz from
(select nvl(max(segblk#),128) maxblk from v$sort_usage) tmsize,
(select value From v$parameter where name = 'db_block_size') bk) b
