Total System Global Area 524288000 bytes
Fixed Size 1220384 bytes
Variable Size 327155936 bytes
Database Buffers 192937984 bytes
Redo Buffers 2973696 bytes
Database mounted.
SYS@ora10g> select * from v$rollname;
select * from V$rollname
*
ERROR at line 1:
ORA-01219: database not open: queries allowed on fixed tables/views only
SYS@ora10g> select segment_name from dba_rollback_segs;
select segment_name from dba_rollback_segs
*
ERROR at line 1:
ORA-01219: database not open: queries allowed on fixed tables/views only
此时通过修改pfile参数文件，然后将undo_management='AUTO'改为undo_management='MANUAL';
并添加隐含参数"_corrupted_rollback_segments"，即添加以下内容到pfile文件中：
_corrupted_rollback_segments='_SYSSMU1$','_SYSSMU2$','_SYSSMU3$','_SYSSMU4$','_SYSSMU5$','_SYSSMU6$','_SYSSMU7$','_SYSSMU8$','_SYSSMU9$','_SYSSMU10$'
目的是将undo管理方式改为手动，并标记这10个默认的回滚段为损坏，然后再用该pfile启动数据库
SYS@ora10g> shutdown abort
ORACLE instance shut down.
SYS@ora10g> startup pfile=/u01/app/oracle/product/10.2.0/db_1/dbs/initora10g.ora
ORACLE instance started.
Total System Global Area 524288000 bytes
Fixed Size 1220384 bytes
Variable Size 327155936 bytes
Database Buffers 192937984 bytes
Redo Buffers 2973696 bytes
Database mounted.
Database opened.
SYS@ora10g>
SYS@ora10g> conn zlm/zlm
Connected.
ZLM@ora10g> select count(*) from t1;
COUNT(*)
----------
20
此时数据库已经能够打开，连接到非系统用户zlm，确认新增的10条数据已经丢失
ZLM@ora10g> select * from v$rollname;
USN NAME
---------- ------------------------------
0 SYSTEM
ZLM@ora10g> select segment_name from dba_rollback_segs;
SEGMENT_NAME
------------------------------
SYSTEM
_SYSSMU1$
_SYSSMU2$
_SYSSMU3$
_SYSSMU4$
_SYSSMU5$
_SYSSMU6$
_SYSSMU7$
_SYSSMU8$
_SYSSMU9$
_SYSSMU10$
11 rows selected.
由于数据库已经正常open,现在回滚段现在已经可以查询到了
还需要将原undo表空间删除并重建，否则还是会有问题，如:非系统用户无法使用系统回滚段
ZLM@ora10g> insert into t1 select * from dba_objects where rownum<11;
insert into t1 select * from dba_objects where rownum<11
*
ERROR at line 1:
ORA-01552: cannot use system rollback segment for non-system tablespace 'ZLM'
ZLM@ora10g> conn / as sysdba
Connected.
SYS@ora10g> insert into zlm.t1 select * from dba_objects where rownum<11;
insert into zlm.t1 select * from dba_objects where rownum<11
*
ERROR at line 1:
ORA-01552: cannot use system rollback segment for non-system tablespace 'ZLM'
--重建UNDO表空间（先删除，后创建）
SYS@ora10g> show parameter undo