ROWNUM & ORDER BY

Question

Dear Oracle experts,
I am not getting the expected output when i use ROWNUM & ORDER BY clause in the same query.
Here is issue. Let us say, we have a table TEST with field last_update_date.
CREATE TABLE TEST(LAST_UPDATE_DATE DATE);
INSERT INTO TEST VALUES(TO_DATE('23-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('23-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('23-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('23-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('23-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('23-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('22-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('21-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('20-MAY-05'));
INSERT INTO TEST VALUES(TO_DATE('13-JUN-04'));
INSERT INTO TEST VALUES(TO_DATE('30-APR-05'));
INSERT INTO TEST VALUES(TO_DATE('09-MAR-05'));
INSERT INTO TEST VALUES(TO_DATE('12-MAY-05'));
select * from TEST
where trunc(LAST_UPDATE_DATE) >= to_date('09-MAR-05')
and trunc(LAST_UPDATE_DATE) <= to_date('22-MAY-05')
and rownum < 3
order by LAST_UPDATE_DATE;
The above query is supposed to return
09-MAR-05
30-APR-05
But it is returning
21-MAY-05
22-MAY-05
If i remove ROWNUM, then it returns in the correct order. But i want to restrict number of records in the same query.
Anybody can help me on this?.
Regards
Govind

Answer 1

Hello all,
I need yours expertise again.
I created FBI on last_update_date. It works fine.
When i run this query without order by clause, it takes only fraction of second to complete the process. If i add order by caluse, it takes for ever to complete the query. The table has 30 million records.
Anybody can help me on this?.
SELECT *
FROM (SELECT *
FROM TEST
where trunc(LAST_UPDATE_DATE) >= to_date('09-MAR-05')
and trunc(LAST_UPDATE_DATE) <= to_date('22-MAY-05')
order by LAST_UPDATE_DATE)
where rownum < 3
Regards
Govind