重建UNDO表空间

$ sqlplus /nolog
SQL>connect /as sysdba
SQL>create undo tablespace UNDOTBS2 datafile '/ora_data/UNDOTBS02.DBF'size 1M extent management local;
SQL>alter system set undo_tablespace=UNDOTBS2;
SQL>drop tablespace UNDOTBS1 including contents;
SQL>shutdown immediate

$rm -f /ora_data/UNDOTBS01.DBF

SQL>startup
SQL>create undo tablespace UNDOTBS1 datafile '/ora_data/UNDOTBS01.DBF' size 2048M extent management local;
SQL>alter system set undo_tablespace=UNDOTBS1;
SQL>drop tablespace UNDOTBS2 including contents;

$rm -f /ora_data/UNDOTBS02.DBF

SQL>shutdown immediate
SQL>startup