SQL> select sum(bytes),status from dba_undo_extents group by status; SUM(BYTES) STATUS ---------- --------- 2621440 UNEXPIRED 32702464 ACTIVE 1384775680 EXPIRED SQL> select begin_time, END_TIME , MAXQUERYLEN,MAXCONCURRENCY,UNEXPIREDBLKS ,EXPIREDBLKS from v$undostat; BEGIN_TIM END_TIME MAXQUERYLEN MAXCONCURRENCY UNEXPIREDBLKS EXPIREDBLKS --------- --------- ----------- -------------- ------------- ----------- 26-FEB-01 26-FEB-01 124 3 3976 169216 26-FEB-01 26-FEB-01 725 0 0 170992 26-FEB-01 26-FEB-01 123 0 0 170992 26-FEB-01 26-FEB-01 725 0 0 170992 26-FEB-01 26-FEB-01 1326 0 0 170992 查看回滚段的使用情况,哪个用户正在使用回滚段的资源,如果有用户最好更换时间(特别是生产环境: SQL> set linesize 200 SQL> select s.sid, s.username, u.name, t.USED_UBLK from v$transaction t, v$rollstat r, v$rollname u, v$session s where s.taddr = t.addr and t.xidusn = r.usn and r.usn = u.usn order by s.username; 2 3 4 5 6 SID USERNAME NAME USED_UBLK ---------- ------------------------------ ------------------------------ ---------- 34 SCOTT _SYSSMU8_3901294357$ 4464 USED_UBLK NUMBER Number of undo blocks used NAME VARCHAR2(30) Rollback segment name