Error in Flashback Query

Question

while trying to execute flashback query i am getting an error
CREATE TABLE flashback_query_test (
id NUMBER(10)
desc flashback_query_test
SELECT current_scn, TO_CHAR(SYSTIMESTAMP, 'YYYY-MM-DD HH24:MI:SS') FROM v$database;
INSERT INTO flashback_query_test (id) VALUES (1)
COMMIT;
SELECT COUNT(*) FROM flashback_query_test
SQL> SELECT COUNT(*)
2 FROM
3 flashback_query_test
4 AS OF
5 TIMESTAMP TO_TIMESTAMP('2010-02-01 16:58:43', 'YYYY-MM-DD HH24:MI:SS');
flashback_query_test
ERROR at line 3:
ORA-01466: unable to read data - table definition has changed
pls help me out!................

Answer 1

The SCN to TIMESTAMP conversion only has a granularity of approximately 3 seconds if I remember correctly. So my guess is that you are getting this error because you are trying to flashback to the same time that the table was created putting you in that 3 second window of SCN to TIMESTAMP ambiguity.
You can see this ambiguity by using the SCN_TO_TIMESTAMP or TIMESTAMP_TO_SCN functions as shown below:
SQL> COLUMN TSTAMP NEW_VALUE T;
SQL> SELECT CURRENT_SCN, TO_CHAR(SYSTIMESTAMP,'YYYY-MM-DD HH24:MI:SS') AS TSTAMP FROM V$DATABASE;
         CURRENT_SCN TSTAMP
       9080346377361 2010-02-01 07:13:12
SQL> SELECT TIMESTAMP_TO_SCN(TO_TIMESTAMP('&T','YYYY-MM-DD HH24:MI:SS')) FROM DUAL;
old   1: SELECT TIMESTAMP_TO_SCN(TO_TIMESTAMP('&T','YYYY-MM-DD HH24:MI:SS')) FROM DUAL
new   1: SELECT TIMESTAMP_TO_SCN(TO_TIMESTAMP('2010-02-01 07:13:12','YYYY-MM-DD HH24:MI:SS')) FROM DUAL
TIMESTAMP_TO_SCN(TO_TIMESTAMP('2010-02-0107:13:12','YYYY-MM-DDHH24:MI:SS'))
                                                              9080346377360See how the SCNs are different?
Now if you allow some time to pass between table creation and INSERT, you should be able to get the results as shown:
SQL> CREATE TABLE FLASHBACK_QUERY_TEST(id NUMBER(10));
Table created.
SQL> EXEC DBMS_LOCK.SLEEP(3);
PL/SQL procedure successfully completed.
SQL> COLUMN TSTAMP NEW_VALUE T;
SQL> SELECT CURRENT_SCN, TO_CHAR(SYSTIMESTAMP,'YYYY-MM-DD HH24:MI:SS') AS TSTAMP FROM V$DATABASE;
         CURRENT_SCN TSTAMP
       9080346377430 2010-02-01 07:15:30
SQL> INSERT INTO FLASHBACK_QUERY_TEST(ID) VALUES(1);
1 row created.
SQL> COMMIT;
Commit complete.
SQL> SELECT COUNT(*) FROM FLASHBACK_QUERY_TEST;
            COUNT(*)
                   1
SQL> SELECT COUNT(*) FROM FLASHBACK_QUERY_TEST AS OF TIMESTAMP TO_TIMESTAMP('&T','YYYY-MM-DD HH24:MI:SS');
old   1: SELECT COUNT(*) FROM FLASHBACK_QUERY_TEST AS OF TIMESTAMP TO_TIMESTAMP('&T','YYYY-MM-DD HH24:MI:SS')
new   1: SELECT COUNT(*) FROM FLASHBACK_QUERY_TEST AS OF TIMESTAMP TO_TIMESTAMP('2010-02-01 07:15:30','YYYY-MM-DD HH24:MI:SS')
            COUNT(*)
                   0HTH!