Do I need to tune the base query of my materialized view ?

Question

Hi gurus,
We implement materialized view (FAST REFRESH ON COMMIT) on base table used in OLTP system. In fact the MV itself is also queried by the OLTP system itself, interactively.
Currently user complain that after they input transaction, they see that the MV is not refresh as soon as they commit the transaction.
(it takes 5 to 10 minutes before they see the update on the MV)
The query of the MV is attached below, it consists of union all of two queries but actually the real query has 13 queries on a UNION ALL.
The question is :
Do I need to tune the query that forms the MV ?
Does it impact the refresh time of the MV ?
Thank you for your help,
xtanto
SELECT GRNH.DOC_CODE ||' '|| GRNH.GRN_NO, GRNH.GRN_DATE, GRNH.REGS_CODE,
F_Convert_Qty_K(GRND.PRODUCT, GRND.QTY, GRND.UOM) QTY_IN, 0 QTY_OUT, 0 QTY_ADJ, 'N/A'.....
FROM GRN_LOCAL_D GRND
          JOIN GRN_LOCAL_H GRNH ON GRNH.GRNH_ID = GRND.GRNH_ID
          WHERE GRND.PRODUCT IS NOT NULL AND GRNH.WH_CODE IS NOT NULL
UNION ALL
SELECT GRNH.DOC_CODE ||' '|| GRNH.GRN_NO, GRNH.GRN_DATE, GRNH.REGS_CODE,
F_Convert_Qty_K(GRND.PRODUCT_B, GRND.QTY_B, GRND.UOM_B) QTY_IN, 0 QTY_OUT, 0 QTY_ADJ, 'N/A'...
FROM GRN_LOCAL_D GRND
JOIN GRN_LOCAL_H GRNH ON GRNH.GRNH_ID = GRND.GRNH_ID
WHERE GRND.PRODUCT_B IS NOT NULL AND GRNH.WH_CODE IS NOT NULL
UNION ALL
     ......

Answer 1

Hi Justin & APC,
Are they seeing a 5-10 minute delay in being able to commit their transaction?NO, the commit itself is completed normally, but after that when they go to the page (this is webbased app) that display data from the MV, the newly committed transactionis not there yet. Only after 5-10 minutes we can see the new data.
What does the F_Convert_Qty_K() function do?It is a function that convert the quantity from whatever Unit Of Measurement (UOM) into the smallest UOM. Below is the code.
So the question remains:
why intermittently theere is delay before the new data visible in the MV ?
Thanks you,
xtanto
CREATE OR REPLACE FUNCTION F_Convert_Qty (pProduct VARCHAR2, pQty NUMBER, pUOM VARCHAR2)
RETURN NUMBER
IS
vQtyBase NUMBER(13,5);
BEGIN
SELECT CASE WHEN pUOM = ( SELECT UOM_BASE FROM PRODUCTS WHERE PRODUCT = pProduct)
          THEN pQty
     ELSE
               SELECT ROUND(pQty * Coefficient / Divisor, 5)
               FROM (
                         SELECT Coefficient, Divisor FROM CONVERT_UOM
                         WHERE PRODUCT = pProduct AND UOM_CONVERT = pUOM
                         ) tmp
          END INTO vQtyBase FROM DUAL;
--RETURN (vQtyBase) ;
RETURN ( NVL(vQtyBase,0) ) ;
END F_Convert_Qty;
/