解決Oracle下的undo空間過大的問題

　　 如果undo表空間undotbs不能釋放空間重建之
    創建備用undo表空間
    create undo tablespace newundotbs datafile $ORA_DATA/newundotbsdbf size m
    /    
    切換undo表空間
    alter system set undo_tablespace=newundotbs scope=spfile
    /
    shutdown immediate
    /
    startup
    /
    drop原表空間
    drop tablespace undotbs including contents and datafiles
    /
    創建原undo表空間
    create undo tablespace undotbs datafile $ORA_DATA/undotbsdbf size m
    /
    切換undo表空間
    alter system set undo_tablespace=undotbs scope=spfile
    /
    關閉重起並把備用undo表空間drop
    shutdown immediate
    /
    startup
    /
    drop tablespace newundotbs including contents and datafiles
    /

From:http://tw.wingwit.com/Article/program/Oracle/201311/17532.html