QUERY HELP

UDA
Enthusiast

QUERY HELP

I am trying to run a query with some complicated calculations at 2 levels
1. class level
2. subclass level

When i do that i see both the queries execution takes much less the same time. I am concerned as to why this is happening as the sublass level has only 1/100 of the data held when compared to class data.

I have collected stats on the key columns and the columns i use for comparison for both the process. Can someone help as to why this is happening? and how i could avoid it.
select t1.* from
(
select a.*,b1.b11,b.b12,b.b13
from a join b b1
where a.key = b.key
join b b2
on b1.b11 = b2.b11
and b1.b12 = b2.b12
and b1.b13 = b2.b13
) t1 join
(
select c.*
from c
where condt_flg = 'Y'
)t2
on t1.keyvalue = t2.kevalue
join
(
select count(d.id) from d
where
) t3
where
t3.key values = t1.keyvalues