Question

I need to query the orders table to get a count of all orders for yesterdays transactions, grouped by the ship date. Then I need to have an additional column to give the total orders for the ship date for all transactions. When I added this second column, time of processing grew exponentially (which was expected) to 109s. Is there any way I could improve this SQL? I just want to know if I’m missing anything fundamental here.

SELECT t.shipping_date
       , t.net_orders
       , count(*) as total_orders
FROM (
    SELECT   s.store_num
             , s.store_cd
             , to_char(o.shipping_date, 'MM/DD/YYYY') as shipping_date
             , COUNT (*) as net_orders
    FROM order o left 
           join store s 
                on ( s.store_num = o.store_num )
    WHERE TRUNC (o.order_date) = TRUNC (SYSDATE - 1)
    AND s.store_cd = 'ZZZ'
    AND o.status in ('A', 'B')
    GROUP BY s.store_num
             , s.store_cd
             , to_char(shipping_date, 'MM/DD/YYYY')
) t
LEFT JOIN order o ON 
          ( TRUNC (o.shipping_date) = to_date(t.shipping_date, 'MM/DD/YYYY') 
            and o.store_num = t.store_num )
WHERE o.status in ('A', 'B')
GROUP BY t.shipping_date, t.net_orders;

I have indexes on all of these columns in addition to the following expressions: TRUNC(order_date) and TRUNC(shipping_date).

Answer 1

I re-wrote your query as:

   SELECT t.shipping_date, 
          t.net_orders, 
          COUNT(*) as total_orders 
     FROM (SELECT s.store_num, 
                  s.store_cd, 
                  o.status,
                  TRUNC(o.shipping_date) AS shipping_date, 
                  COUNT (*) as net_orders
             FROM STORE s
             JOIN ORDER o ON o.store_num = s.store_num
                         AND o.status IN ('A', 'B')
            WHERE s.store_cd = 'ZZZ'
              AND TRUNC(order_date) = TRUNC (SYSDATE - 1)
  GROUP BY s.store_num, s.store_cd, TRUNC(shipping_date)) t
LEFT JOIN ORDER o ON TRUNC(o.shipping_date) = t.shipping_date
                 AND o.store_num = t.store_num
                 AND o.status = t.status
 GROUP BY t.shipping_date, t.net_orders;

Some minor re-arrangement, but I did get rid of the TO_CHAR(shipping_date) which is later converted back to a DATE. TRUNC(shipping_date) is the same, and simplifies the operation.

Joining on criteria using functions won’t use an index – you’ll need to create a function based index matching the JOIN criteria.