After partition, query returns wrong result.

[yansheng lin]

Hi, I set up monthly partition on the log_hour field for one of my tables, books. When I do a select on the max(log_hour), if I only specify one condition in my where clause, everything looks fine. But if I specify two conditions in the where clause, it gave me the wrong result back. The partitioning function is very simple -- Partition By Range (year(log_hour)*100+month(log_hour). What's going on?

mysql> select max(log_hour) from books where
mysql> book_id = 266 and department_id = 1;
+---------------------+
| max(log_hour) |
+---------------------+
| 2006-04-30 23:00:00 |
+---------------------+
1 row in set (0.07 sec)

mysql> select max(log_hour) from books where
mysql> department_id = 1;
+---------------------+
| max(log_hour) |
+---------------------+
| 2006-05-19 08:00:00 |
+---------------------+
1 row in set (0.07 sec)

mysql> select max(log_hour) from books where
mysql> book_id = 266;
+---------------------+
| max(log_hour) |
+---------------------+
| 2006-05-19 08:00:00 |
+---------------------+
1 row in set (0.07 sec)

mysql> select max(log_hour) from books where
mysql> book_id = 266 and department_id = 1;
+---------------------+
| max(log_hour) |
+---------------------+
| 2006-04-30 23:00:00 |
+---------------------+
1 row in set (0.07 sec)