SQL> col scn for 9999999999999
SQL> 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 number
ORA-06512: at "SYS.SCN_TO_TIMESTAMP", line 1
ORA-06512: at line 1
SQL> select scn_to_timestamp(8908393582271) scn from dual;SCN
---------------------------------------------------------------------------
05-JAN-07 11.45.50.000000000 AM