Key/table cache size?

[Michael T. Babcock]

I've got a query that selects the count of distinct rows in a table; the 
table has 453632 rows and 24 distinct class_id's.

mysql> SELECT count(DISTINCT(sig_class_id)) FROM acid_event;
+-------------------------------+
| count(DISTINCT(sig_class_id)) |
+-------------------------------+
|                            24 |
+-------------------------------+
1 row in set (4.80 sec)

mysql> select count(*) FROM acid_event;
+----------+
| count(*) |
+----------+
|   453632 |
+----------+
1 row in set (3.12 sec)


Is there any way to speed up these queries (InnoDB tables), or just put up?

PS, at that number of distinct values, am I right in thinking that I 
should just drop the index on that column while I'm at it?

-- 
Michael T. Babcock
C.T.O., FibreSpeed Ltd.
http://www.fibrespeed.net/~mbabcock