[Oracle]在没有备份的情况下undo损坏怎么办(二)
ystem reset "_offline_rollback_segments" scope=spfile;
重启使其生效：
SQL> shutdown immediate;
SQL> startup
SQL> show parameter undo
NAME TYPE VALUE
------------------------------------ ----------- -------------------
undo_management string AUTO
undo_retention integer 900
undo_tablespace string undo2
最终检查一下：
SQL> select segment_name,status from dba_rollback_segs;
SEGMENT_NAME STATUS
------------------------------ ----------------
SYSTEM ONLINE
_SYSSMU40_1968985325$ ONLINE
_SYSSMU39_4040503138$ ONLINE
_SYSSMU38_4059847715$ ONLINE
_SYSSMU37_2692202156$ ONLINE
_SYSSMU36_2617425201$ ONLINE
_SYSSMU35_1133967719$ ONLINE
_SYSSMU34_1916939664$ ONLINE
_SYSSMU33_99444166$ ONLINE
_SYSSMU32_162619813$ ONLINE
_SYSSMU31_830375278$ ONLINE