UNDO表空间使用率过高的处理方式

文档课题：UNDO表空间使用率过高的处理方式.

应用场景：UNDO表空间使用率过高，想必很多数据库管理员都遇到过此问题，接下来了解undo表空间的相关知识.

1、undo块使用情况

SQL>select status,sum(bytes/1024/1024) from dba_undo_extents group by status;

STATUS SUM(BYTES/1024/1024)

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

EXPIRED 21.25

UNEXPIRED 10

2、当前undo空闲

SQL> selecttablespace_name,sum(bytes/1024/1024) from dba_free_space wheretablespace_name='UNDOTBS1' group by tablespace_name

TABLESPACE_NAME SUM(BYTES/1024/1024)

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

UNDOTBS1 157.75

3、表空间情况

SQL>set line 200

SQL>col GRAPH for a50

SQL>col tablespace for a20

SQL> select total.ts tablespace,

total.mb total_mb,

to_char(trunc(total.mb -nvl(free.mb,0),2),'fm999990.0999') used_MB,

NVL(free.mb,0) f