Peformance fine tunning of query

Question

Am using co related subquery, please help because it's taking more time when dealing with more number of rows
below is my sample query.
SELECT EM.ENTITY_ID,
EM.ENTITY_DESC,
EM.UNIT_ID,
EM.UNIT_DESC,
EM.OC_ID,
EM.OC_DESC,
EM.SBU_ID,
EM.SBU_DESC,
EM.COST_CENTRE_ID,
EM.COST_CENTRE_DESC,
EM.LOCATION_ID,
EM.LOCATION_DESC,
EM.BAND_ID,
EM.BAND_DESC,
EM.GRADE_ID,
EM.GRADE_DESC,
EM.PSNO,
EM.EMPLOYEE_ID,
EM.EMPLOYEE_NAME,
H.MEDH_CLAIM_TYPE_ID AS CLAIM_TYPE_ID,
H.MEDH_CLAIM_NO AS CLAIM_NO,
H.MEDH_CLAIM_DATE AS CLAIM_DATE,
vCurrencyCode CURRENCY_ID,
EBC_Fn_Currency_Desc (vCurrencyCode) CURRENCY_DESC,
Nvl(
Select
SUM(NVL (D1.MEDD_CLAIMED_AMOUNT,0))
From ebcuser.EBC_D_MEDICAL_CLAIM D1 Where H.MEDH_CLAIM_NO = D1.MEDD_CLAIM_NO AND D1.MEDD_DELETED_BY IS NULL
,0) AS CLAIM_AMOUNT,
Nvl(
Select
NVL (
SUM(CASE
WHEN (D2.MEDD_R_APPROVED_AMOUNT) IS NULL
THEN
(D2.MEDD_APPROVED_AMOUNT)
ELSE
(D2.MEDD_R_APPROVED_AMOUNT)
END),
0.00)
From ebcuser.EBC_D_MEDICAL_CLAIM D2 Where H.MEDH_CLAIM_NO = D2.MEDD_CLAIM_NO AND D2.MEDD_DELETED_BY IS NULL
,0) AS PAYABLE_AMOUNT,
H.MEDH_CREATED_BY AS CREATED_BY,
H.MEDH_CREATED_ON AS CREATED_ON,
H.MEDH_PROCESSED_BY AS PROCESSED_BY,
H.MEDH_PROCESSED_ON AS PROCESSED_ON,
H.MEDH_ERA_BATCH_NO AS ERA_BATCH_NO,
MEDH_QUEUE_STATUS AS ERA_BATCH_STATUS, --Q - Queued for BPV, B - BVP generated, J - JV generated
EM.EMP_BANK_IFSC_CODE,
EM.EMP_BANK_ACNO,
EM.EMP_PAY_MODE,
EM.EMP_ACTIVE_STATUS,
H.MEDH_RECEIVED_ON,
H.MEDH_SCRUTINIZED_ON
FROM GEN_V_EMPLOYEE_DATA EM,
EBC_H_MEDICAL_CLAIM H
WHERE H.MEDH_EMPLOYEE_ID = EM.EMPLOYEE_ID
AND H.MEDH_PROCESSED_BY IS NOT NULL
and ( (H.MEDH_ERA_BATCH_NO is not null
AND (EBCUSER.EBC_FN_PAYMENT_DATE(H.MEDH_ERA_BATCH_NO) BETWEEN vPeriod_From AND vPeriod_Upto) and vType_Tag='P' )
or
( vType_Tag='C' and ( H.MEDH_CLAIM_DATE BETWEEN vPeriod_From AND vPeriod_Upto ) )
);

Answer 1

Is there any chance you can move the logic from your function call into the SQL query?
AND
   EBCUSER.EBC_FN_PAYMENT_DATE(H.MEDH_ERA_BATCH_NO) BETWEEN vPeriod_From AND vPeriod_Upto) and vType_Tag='P'
)If not, do you high a high degree of repeatably in the data you are passing to the function?
If so, you may greatly benefit from using scalar subquery caching
AND
   (select EBCUSER.EBC_FN_PAYMENT_DATE(H.MEDH_ERA_BATCH_NO) from dual)
   BETWEEN vPeriod_From AND vPeriod_Upto) and vType_Tag='P'
)which you can read about here.
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:8491662046178
and in many other threads on AskTom.
Also
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1547006324238
may be of some benefit.
This all assumes that the function call is what is actually causing you problems (perhaps a bad assumption). You should be running a trace (TKPROF or AWR or something) to get an idea of why this query is actually causing you problems.
Also, as you are new to the forum, please read the FAQ so you learn things like using the tags to preserve the formatting of your code like i did above.