Long Running Queries Using Group By & Order By

Question

I have his query and it takes forever to run. The TABLE 'term' has over a million rows and I think that the 'group by' and the 'Order By' together is killing the execution...
Or is it due to the compute clauses.. I am at loss to understand the whole issue..
Any ideas or thougts on how to solve this issue. Oracle Version is 8.1.6 ...
Please help !!!!
Thanx
Rama
====================
set pages 10000;
set heading on;
compute sum of total on area
compute sum of total on report
break on area skip 2 on report
SELECT c.area area
, b.modelcode model
, count(1) total
FROM leadterm a
,lead e
,term b
,temp_veh b
,leaddealer d
,dealer c
WHERE
a.leadid not in (select leadid from leadno_tmp)
and a.leadid = e.leadid
and a.termid = b.termid
and e.leaddealerid = d.leaddealerid
and ltrim(rtrim(d.vwdealercode)) = ltrim(rtrim(c.dealercode))
group by c.area
, b.modelcode
order by to_number(c.area)
, b.modelcode
exit;

Answer 1

Did you run this query through the explain plan yet?
A few thoughts:
- Order by is not needed, since group by automatically sorts the records.
- Assuming that dealercode is a primary key, ltrim and rtrim functions will cause Oracle NOT to use indexes, but a full table scan. If a foreign key is defined, then ltrim and rtrim should not be necessary at all.
- Instead of "not in" use "where not exists"