I have an index on (col1, col2). The following query uses this index and EXPLAIN SELECT says "Using Where", great!
Code:
SELECT * FROM table WHERE col1=2 ORDER BY col2 DESC
But the follwing slightly modified query says "Using where; Using filesort":
Code:
SELECT * FROM table WHERE col1 IN (2,3) ORDER BY col2 DESC
Why doesn´t it use the index to sort the rows in this case?

I´m using MySQL 4.0.23, might this be a bug?