SQL> col scn for 9999999999999SQL> select dbms_flashback.get_system_change_number scn from dual;SCN--------------8908390522972

SQL> select scn_to_timestamp(8908390522972) scn from dual;SCN-----------------------------------------------------------05-JAN-07 10.56.30.000000000 AM

SQL> select timestamp_to_scn(scn_to_timestamp(8908390522972)) scn from dual; SCN--------------8908390522972

SQL> select min(FIRST_CHANGE#) scn,max(FIRST_CHANGE#) scn from v$archived_log;SCN SCN------------------ ------------------8907349093953 8908393582271SQL> select scn_to_timestamp(8907349093953) scn from dual;select scn_to_timestamp(8907349093953) scn from dual*ERROR at line 1:ORA-08181: specified number is not a valid system change numberORA-06512: at "SYS.SCN_TO_TIMESTAMP", line 1ORA-06512: at line 1SQL> select scn_to_timestamp(8908393582271) scn from dual;SCN--------------------------------------------------------05-JAN-07 11.45.50.000000000 AM