DataFile大小调整Script
昨天学习了Oracle中的datafile大小的增长方式，当然一定会想到如果datafile被“撑”大之后，如何缩小datafile的大小呢？怎么知道这个datafile的真正被使用的实际大小是多少呢？以下就摘录tom用来计算datafile可缩减大小的脚本。这个脚本在我第一次看到的时候，对我有很大的启发，甚至很大程度上改变了我的编码习惯。看上去真的是相当赏心悦目，多年的程序员下来，一定会追求形式上的美感。
----------- maxshrink.sql ----------------------------------
set verify off
column file_name format a50 word_wrapped
column smallest format 999,990 heading "Smallest|Size|Poss."
column currsize format 999,990 heading "Current|Size"
column savings format 999,990 heading "Poss.|Savings"
break on report
compute sum of savings on report
column value new_val blksize
select value from v$parameter where name = 'db_block_size'
/
select file_name,
ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) smallest,
ceil( blocks*&&blksize/1024/1024) currsize,
ceil( blocks*&&blksize/1024/1024) -
ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) savings
from dba_data_files a,
( select file_id, max(block_id+blocks-1) hwm
from dba_extents
group by file_id ) b
where a.file_id = b.file_id(+)
/
column cmd format a75 word_wrapped
select 'alter database datafile '''||file_name||''' resize ' ||
ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) || 'm;' cmd
from dba_data_files a,
( select file_id, max(block_id+blocks-1) hwm
from dba_extents
group by file_id ) b
where a.file_id = b.file_id(+)
and ceil( blocks*&&blksize/1024/1024) -
ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) > 0
/
-------------------------------------------------------------------------------
执行结果：
SQL> set verify off
SQL> column file_name format a50 word_wrapped
SQL> column smallest format 999,990 heading "Smallest|Size|Poss."
SQL> column currsize format 999,990 heading "Current|Size"
SQL> column savings format 999,990 heading "Poss.|Savings"
SQL> break on report
SQL> compute sum of savings on report
SQL> column value new_val blksize
SQL> select value from v$parameter where name = 'db_block_size'
2 /
VALUE
-----------
8192
SQL> select file_name,
2 ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) smallest,
3 ceil( blocks*&&blksize/1024/1024) currsize,
4 ceil( blocks*&&blksize/1024/1024) -
5 ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) savings
6 from dba_data_files a,
7 (select file_id, max(block_id+blocks-1) hwm
8 from dba_extents
9 group by file_id ) b
10 where re a.file_id = b.file_id(+)
11 /
Smallest
Size Current Poss.
FILE_NAME Poss. Size Savings
--------------------------------------------------- ------- -------- --------
E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\SYSTEM01.DBF 478 480 2
E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\UNDOTBS01.DBF 15 25 10
E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\USERS01.DBF 2 5 3
E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\PERFSTAT.DBF 144 500 356
E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\SYSAUX01.DBF 251 260 9
--------
sum 380
SQL>
column cmd format a75 word_wrapped
SQL> select 'alter database datafile '''||file_name||''' resize ' ||
2 ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) || 'm;' cmd
3 from dba_data_files a,
4 ( select file_id, max(block_id+blocks-1) hwm
5 from dba_extents
6 group by file_id ) b
7 where a.file_id = b.file_id(+)
8 and ceil( blocks*&&blksize/1024/1024) -
9 ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) > 0
10 /
CMD
------------------------------------------------------------------------------------------
alter database datafile 'E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\SYSTEM01.DBF' resize 478m;
alter database datafile 'E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\UNDOTBS01.DBF' resize 15m;
alter database datafile 'E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\USERS01.DBF' resize 2m;
alter database datafile 'E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\PERFSTAT.DBF' resize 144m;
alter database datafile 'E:\ORACLE\PRODUCT\10.2.0\ORADATA\DODO\SYSAUX01.DBF' resize 251m;
-------------------------------------------------------------------------------------------
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