group by

Hi,

I notices a weird thing here.

version 7.2.1
on Solaris

table "test", has a field "state".
There are 4 "state" values, 1, 2, 3, 4.

select count(*) from test group by state;
took 11500 msec

but

select count(*) from test where state = 1;
select count(*) from test where state = 2;
select count(*) from test where state = 3;
select count(*) from test where state = 4;
total took 626 msec

Why ??

thanks,
kathy