undo自動管理下刪除回滾段比如undo出現壞塊

測試：
SQL> drop rollback segment "_SYSSMU10$";
drop rollback segment "_SYSSMU10$"
*
ERROR at line 1:
ORA-30025: DROP segment '_SYSSMU10$' (in undo tablespace) not allowed

刪除沒有成功

修改參數

SQL> alter session set "_smu_debug_mode"=4;

Session altered.

SQL> drop rollback segment "_SYSSMU10$";
drop rollback segment "_SYSSMU10$"
*
ERROR at line 1:
ORA-01545: rollback segment '_SYSSMU10$' specified not available

還是沒有刪除回滾段

查看回滾段的狀態：

SQL> select segment_name,status from dba_rollback_segs;

SEGMENT_NAME                   STATUS
------------------------------ ----------------
SYSTEM                         ONLINE
_SYSSMU1$                      ONLINE
_SYSSMU2$                      ONLINE
_SYSSMU3$                      ONLINE
_SYSSMU4$                      ONLINE
_SYSSMU5$                      ONLINE
_SYSSMU6$                      ONLINE
_SYSSMU7$                      ONLINE
_SYSSMU8$                      ONLINE
_SYSSMU9$                      ONLINE
_SYSSMU10$                     ONLINE

可以發現_SYSSMU10$ 回滾段狀態為online
將_SYSSMU10$ 改為offline

SQL> alter rollback segment "_SYSSMU10$" offline;

Rollback segment altered.

SQL> drop rollback segment  "_SYSSMU10$";

Rollback segment dropped.

成功刪除

結論總結：

刪除在綫的回滾段的步驟為：

1 修改數據庫參數_smu_debug_mode=4

2 將online回滾段狀態該為offline

3 drop offline 的回滾段。