用Oracle LogMiner挖不出数据报In Memory Undo is unsupported

最近在用LogMiner在Oracle 10g上进行日志挖掘，无意之中create table test as select * from v$logmnr_contents; 发现其实是有记录的，只是记录的内容无法解析，info字段报In Memory Undo is unsupported这个问题。几经周折，加上附件日志就ok了，下面是实验再现： 

C:\Documents and Settings\guogang>sqlplus test/test

SQL> create table tt as select rownum rn from dual connect by rownum <10;
表已创建。

第一次做实验：

SQL> select to_char(dbms_flashback.get_system_change_number) from dual;
TO_CHAR(DBMS_FLASHBACK.GET_SYSTEM_CHANGE
----------------------------------------
10309235923278

SQL> delete from tt where rn=1;
已删除 1 行。
SQL> commit;
提交完成。
SQL> select to_char(dbms_flashback.get_system_change_number) from dual;
TO_CHAR(DBMS_FLASHBACK.GET_SYSTEM_CHANGE
----------------------------------------
10309235923281

SQL> alter database add supplemental log data;--一定要加上附加日志

数据库已更改。

第二次做实验：
SQL> select to_char(dbms_flashback.get_system_change_number) from dual;
TO_CHAR(DBMS_FLASHBACK.GET_SYSTEM_CHANGE
----------------------------------------
10309235923453

SQL> delete from tt where rn=2;
已删除 1 行。
SQL> commit;
提交完成。

SQL> select to_char(dbms_flashback.get_system_change_number) from dual;
TO_CHAR(DBMS_FLASHBACK.GET_SYSTEM_CHANGE
----------------------------------------
10309235923456

C:\Documents and Settings\guogang>sqlplus / as sysdba;

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