2024年6月15日发(作者：)

如何释放过度占用的Shrink Undo表空间

环境:

OS:Red Hat Enterprise Linux AS release 4 (Nahant)

DB:Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production

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

from v$rollstat order by rssize;

USN XACTS STATUS RSSIZE/1024/1024/1024 HWMSIZE/1024/1024/1024 SHRINK

S

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

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 SHRIN

KS

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

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 SHRIN