ORA-01552 做实验时，修改了undo段的管理模式

undo 段为手动管理模式，是因为做实验时，修改了undo段的管理模式。

 

1.查看undo段状态SQL> col segment_name for a20SQL> col owner for a10SQL> col tablespace_name for a20SQL> col status for a10SQL> select SEGMENT_NAME,OWNER,TABLESPACE_NAME,STATUS from dba_rollback_segs;SEGMENT_NAME     OWNERTABLESPACE_NAME      STATUS-------------------- ---------- -------------------- ----------SYSTEM         SYSSYSTEM     ONLINE_SYSSMU1_592353410$  PUBLICUNDOTBS1     OFFLINE_SYSSMU2_967517682$  PUBLICUNDOTBS1     OFFLINE_SYSSMU3_1204390606$ PUBLICUNDOTBS1     OFFLINE_SYSSMU4_1003442803$ PUBLICUNDOTBS1     OFFLINE_SYSSMU5_538557934$  PUBLICUNDOTBS1     OFFLINE_SYSSMU6_2897970769$ PUBLICUNDOTBS1     OFFLINE_SYSSMU7_3517345427$ PUBLICUNDOTBS1     OFFLINE_SYSSMU8_3901294357$ PUBLICUNDOTBS1     OFFLINE_SYSSMU9_1735643689$ PUBLICUNDOTBS1     OFFLINE_SYSSMU10_4131489474 PUBLICUNDOTBS1     OFFLINESEGMENT_NAME     OWNERTABLESPACE_NAME      STATUS-------------------- ---------- -------------------- ----------$2.查看当前的undo段是哪一个？SQL> select * from v$rollname;       USN NAME---------- ------------------------------     0 SYSTEM发现undo段为系统表空间 3.查看undo段的管理模式SQL> show parameter undoNAME                     TYPE VALUE------------------------------------ ----------- ------------------------------undo_management                 string MANUALundo_retention                integer 900undo_tablespace                 string UNDOTBS1SQL> SQL> 为手动管理模式，是因为做实验时，修改了undo段的管理模式。4.切换管理模式为自动SQL> alter system set undo_management=auto scope=spfile;System altered.SQL> show parameter undoNAME     TYPE VALUE------------------------------------ ----------- ------------------------------undo_management      string MANUALundo_retention     integer 900undo_tablespace      string UNDOTBS15.重新启动数据库后，查看状态，已改为AUTO模式。问题解决。SQL> help shutdown SHUTDOWN -------- Shuts down a currently running Oracle Database instance, optionally closing and dismounting a database. SHUTDOWN [ABORT|IMMEDIATE|NORMAL|TRANSACTIONAL [LOCAL]]SQL> shutdown immediateDatabase closed.Database dismounted.ORACLE instance shut down.SQL> SQL> startupORACLE instance started.Total System Global Area  422670336 bytesFixed Size    1336960 bytesVariable Size  314575232 bytesDatabase Buffers  100663296 bytesRedo Buffers    6094848 bytesDatabase mounted.Database opened.SQL> SQL> show parameter undoNAME         TYPE     VALUE------------------------------------ ----------- ------------------------------undo_management      string     AUTOundo_retention     integer 900undo_tablespace      string     UNDOTBS1SQL> SQL> SQL> col owner for a10SQL> col tablespace_name for a20SQL> col status for a10SQL> select SEGMENT_NAME,OWNER,TABLESPACE_NAME,STATUS from dba_rollback_segs;SEGMENT_NAME     OWNERTABLESPACE_NAME      STATUS-------------------- ---------- -------------------- ----------SYSTEM         SYSSYSTEM     ONLINE_SYSSMU1_592353410$  PUBLICUNDOTBS1     ONLINE_SYSSMU2_967517682$  PUBLICUNDOTBS1     ONLINE_SYSSMU3_1204390606$ PUBLICUNDOTBS1     ONLINE_SYSSMU4_1003442803$ PUBLICUNDOTBS1     ONLINE_SYSSMU5_538557934$  PUBLICUNDOTBS1     ONLINE_SYSSMU6_2897970769$ PUBLICUNDOTBS1     ONLINE_SYSSMU7_3517345427$ PUBLICUNDOTBS1     ONLINE_SYSSMU8_3901294357$ PUBLICUNDOTBS1     ONLINE_SYSSMU9_1735643689$ PUBLICUNDOTBS1     ONLINE_SYSSMU10_4131489474 PUBLICUNDOTBS1     ONLINESEGMENT_NAME     OWNERTABLESPACE_NAME      STATUS-------------------- ---------- -------------------- ----------$11 rows selected.SQL> conn scott/tigerConnected.SQL> create table t1 as select * from emp;Table created.SQL>