Oracle SQL “complex” group by query optimization

Question

I have an Oracle Report (10g) where i created several graphs.

Now i use two statements like the following in this report. I feel like i had to use two sub-selects in order to get all information the way i want it. But the report now uses 7min to generate and i'm wondering if there's anyway to optimize this query

SELECT quantity ,
  commodity ,
  TO_CHAR(quantity,'9999999990.000') string_quantity
FROM
  (SELECT SUM(quantity) quantity ,
    commodity
  FROM
    (SELECT vtr.quant_p quantity,
      DECODE(vtr.commo_num,'CU','CU,MS,PB','MS','CU,MS,PB','PB','CU,MS,PB',vtr.commo_num) commodity
    FROM v_transactions_postp vtr
    WHERE vtr.compa_num = :P_COMPA_NUM
    AND vtr.customer    = :P_CUSTOMER
    AND vtr.POSTPERIOD BETWEEN :P_PP_START AND :P_PP_END
    )
  GROUP BY commodity
  )
ORDER BY quantity DESC

Answer 1

First, you don't need all the subqueries. And CASE is preferable to DECODE() , especially in this case where it simplifies the code:

SELECT SUM(vtr.quant_p) as quantity,  
       (CASE WHEN vtr.commo_num IN ('CU', 'MS', 'PB') THEN 'CU,MS,PB'
             ELSE vtr.commo_num
        END) as commodity
       TO_CHAR(SUM(vtr.quant_p),'9999999990.000') as string_quantity
FROM v_transactions_postp vtr
WHERE vtr.compa_num = :P_COMPA_NUM AND
      vtr.customer    = :P_CUSTOMER AND
      vtr.POSTPERIOD BETWEEN :P_PP_START AND :P_PP_END
GROUP BY (CASE WHEN vtr.commo_num IN ('CU', 'MS', 'PB') THEN 'CU,MS,PB'
               ELSE vtr.commo_num
          END)
ORDER BY SUM(vtr.quant_p) DESC

Then, for performance, you want an index on v_transactions_postp(compa_num, customer, postperiod) . However, I suspect that the "v_" means "view". That can make the query harder to optimize. You would need the appropriate index on the underlying tables -- or to expand the view in the query.

Answer 2

Try below query:

SELECT sum(vtr.quant_p) quantity,
 (CASE WHEN vtr.commo_num IN ('CU','MS','PB') THEN 'CU,MS,PB' ELSE vtr.commo_num) commodity,
 TO_CHAR(sum(vtr.quant_p), '9999999990.000') string_quantity
 FROM v_transactions_postp vtr
   WHERE vtr.compa_num = :P_COMPA_NUM
     AND vtr.customer = :P_CUSTOMER
     AND vtr.POSTPERIOD BETWEEN :P_PP_START AND :P_PP_END
     GROUP BY commodity
     ORDER BY quantity DESC;

I would suggest you avoid using TO_CHAR in query just to format it in decimal format. You can get quantity and then add formation logic in your code, say in JAVA or PHP.