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Shrink Undo表空间,释放过度占用的空间

环境:
OS:Red Hat Enterprise Linux AS release 4 (Nahant)
DB:Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
一台Oracle10gR2数据库报出如下错误:

 

 

 

 

 

ORA-1653: unable to extend table SYSMAN.MGMT_SYSTEM_ERROR_LOG by 8 in  tablespace SYSAUX 

ORA-1653: unable to extend table SYSMAN.MGMT_SYSTEM_ERROR_LOG by 8 in  tablespace SYSAUX 

ORA-1653: unable to extend table SYSMAN.MGMT_SYSTEM_ERROR_LOG by 8 in  tablespace SYSAUX 

ORA-1653: unable to extend table SYSMAN.MGMT_SYSTEM_ERROR_LOG by 8 in  tablespace SYSAUX 

ORA-1653: unable to extend table SYSMAN.MGMT_SYSTEM_ERROR_LOG by 8 in  tablespace SYSAUX

      

登陆检查,发现是SYSAUX表空间空间用尽,不能扩展,尝试手工扩展SYSAUX表空间:
alter database datafile '+ORADG/danaly/datafile/sysaux.266.600173881' resize 800m

Tue Nov 29 23:31:38 2005

ORA-1237 signalled during: alter database datafile 
'+ORADG/danaly/datafile/sysaux.266.600173881' resize 800m...

出现ORA-1237错误,提示空间不足。这时候我才认识到是磁盘空间可能被用完了.

是谁"偷偷的"用了那么多空间呢(本来有几十个G的Free磁盘空间的)?
检查数据库表空间占用空间情况:
SQL> select tablespace_name,sum(bytes)/1024/1024/1024 GB

  2  from dba_data_files group by tablespace_name

  3  union all

  4  select tablespace_name,sum(bytes)/1024/1024/1024 GB

  5  from dba_temp_files group by tablespace_name order by GB;

TABLESPACE_NAME                        GB

------------------------------ ----------

USERS                          .004882813

UNDOTBS2                        .09765625

SYSTEM                         .478515625

SYSAUX                         .634765625

WAPCM_TS_VISIT_DETAIL            .9765625

HY_DS_DEFAULT                           1

MINT_TS_DEFAULT                         1

MMS_TS_DATA2                        1.375

MMS_IDX_SJH                             2

MMS_TS_DEFAULT                          2

IVRCN_TS_DATA                           2

TABLESPACE_NAME                        GB

------------------------------ ----------

MMS_TS_DATA1                            2

CM_TS_DEFAULT                           5

TEMP                           20.5498047

UNDOTBS1                       27.1582031

15 rows selected.

      

不幸的发现,UNDO表空间已经扩展至27G,而TEMP表空间也扩展至20G,这2个表空间加起来占用了47G的磁盘空间,导致了空间不足。
显然曾经有大事务占用了大量的UNDO表空间和Temp表空间,Oracle的AUM(Auto Undo Management)从出生以来就经常出现只扩展,不收缩(shrink)的情况(通常我们可以设置足够的UNDO表空间大小,然后取消其自动扩展属性).
现在我们可以采用如下步骤回收UNDO空间:

1.确认文件
SQL> select file_name,bytes/1024/1024 from dba_data_files

  2  where tablespace_name like 'UNDOTBS1';

FILE_NAME

--------------------------------------------------------------------------------

BYTES/1024/1024

---------------

+ORADG/danaly/datafile/undotbs1.265.600173875

          27810

      

2.检查UNDO Segment状态
SQL> select usn,xacts,rssize/1024/1024/1024,hwmsize/1024/1024/1024,shrinks

  2  from v$rollstat order by rssize;

       USN      XACTS RSSIZE/1024/1024/1024 HWMSIZE/1024/1024/1024    SHRINKS

---------- ---------- --------------------- ---------------------- ----------

         0          0            .000358582             .000358582          0

         2          0            .071517944             .071517944          0

         3          0             .13722229              .13722229          0

         9          0            .236984253             .236984253          0

        10          0            .625144958             .625144958          0

         5          1            1.22946167             1.22946167          0

         8          0            1.27175903             1.27175903          0

         4          1            1.27895355             1.27895355          0

         7          0            1.56770325             1.56770325          0

         1          0            2.02474976             2.02474976          0

         6          0             2.9671936              2.9671936          0

11 rows selected.

      

3.创建新的UNDO表空间
SQL> create undo tablespace undotbs2;

Tablespace created.

      

4.切换UNDO表空间为新的UNDO表空间
SQL> alter system set undo_tablespace=undotbs2 scope=both;

System altered.

      

此处使用spfile需要注意,以前曾经记录过这样一个案例:Oracle诊断案例-Spfile案例一则
5.等待原UNDO表空间所有UNDO SEGMENT OFFLINE
SQL> select usn,xacts,status,rssize/1024/1024/1024,hwmsize/1024/1024/1024,shrinks

  2 from v$rollstat order by rssize;

       USN      XACTS STATUS          RSSIZE/1024/1024/1024 HWMSIZE/1024/1024/1024    SHRINKS

---------- ---------- --------------- --------------------- ---------------------- ----------

        14          0 ONLINE                     .000114441             .000114441          0

        19          0 ONLINE                     .000114441             .000114441          0

        11          0 ONLINE                     .000114441             .000114441          0

        12          0 ONLINE                     .000114441             .000114441          0

        13          0 ONLINE                     .000114441             .000114441          0

        20          0 ONLINE                     .000114441             .000114441          0

        15          1 ONLINE                     .000114441             .000114441          0

        16          0 ONLINE                     .000114441             .000114441          0

        17          0 ONLINE                     .000114441             .000114441          0

        18          0 ONLINE                     .000114441             .000114441          0

         0          0 ONLINE                     .000358582             .000358582          0

       USN      XACTS STATUS          RSSIZE/1024/1024/1024 HWMSIZE/1024/1024/1024    SHRINKS

---------- ---------- --------------- --------------------- ---------------------- ----------

         6          0 PENDING OFFLINE             2.9671936              2.9671936          0

12 rows selected.

      

再看:
11:32:11 SQL> /

       USN      XACTS STATUS          RSSIZE/1024/1024/1024 HWMSIZE/1024/1024/1024    SHRINKS

---------- ---------- --------------- --------------------- ---------------------- ----------

        15          1 ONLINE                     .000114441             .000114441          0

        11          0 ONLINE                     .000114441             .000114441          0

        12          0 ONLINE                     .000114441             .000114441          0

        13          0 ONLINE                     .000114441             .000114441          0

        14          0 ONLINE                     .000114441             .000114441          0

        20          0 ONLINE                     .000114441             .000114441          0

        16          0 ONLINE                     .000114441             .000114441          0

        17          0 ONLINE                     .000114441             .000114441          0

        18          0 ONLINE                     .000114441             .000114441          0

        19          0 ONLINE                     .000114441             .000114441          0

         0          0 ONLINE                     .000358582             .000358582          0

11 rows selected.

Elapsed: 00:00:00.00

      

6.删除原UNDO表空间
11:34:00 SQL> drop tablespace undotbs1 including contents;

Tablespace dropped.

Elapsed: 00:00:03.13

      

7.检查空间情况
由于我使用的ASM管理,可以使用10gR2提供的信工具asmcmd来察看空间占用情况.
[oracle@danaly ~]$ export ORACLE_SID=+ASM

[oracle@danaly ~]$ asmcmd

ASMCMD> du 

Used_MB      Mirror_used_MB

  21625               21625

ASMCMD> exit

      

空间已经释放。
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