Last week, we faced a basic and yet the only major problem that sql developers/admin had to deal with and yes your guess is right, It was with SQL QUERY RUNNING SLOW. I will be explaining the problem below, however I want everyone reading this to help me find answers because I still haven't found one!
One more amazing aspect of the issue was that it worked fairly quickly in Development but was running like a tortoise in Production even though the number of records were practically the same.
I'll start by throwing some light on to the execution plan, so that we narrow down to the code which was the culprit here. The code is enclosed into a stored proc. On contacting my dba to enquire about the issue, I got the following replay:-
One more amazing aspect of the issue was that it worked fairly quickly in Development but was running like a tortoise in Production even though the number of records were practically the same.
I'll start by throwing some light on to the execution plan, so that we narrow down to the code which was the culprit here. The code is enclosed into a stored proc. On contacting my dba to enquire about the issue, I got the following replay:-
I must hand it to our dba to provide such a detailed response.
So my job was now to look at the code and modify it. What I did was to shrink the calender table into a temp table consisting of few rows that would speed up the operation. Below you would see the culprit code and a rectified version of it.
Culprit Code :-
-- Customer Table and latest advertiser with complete hierarichy details
INSERT INTO reporting.Obtain_CustAM_Hier
SELECT cod.AdvertiserId ,
cod.SalesConsultantId AS end_employee_sid ,
COALESCE(st10.end_org_team_key, stmax.END_ORG_TEAM_KEY) end_org_team_key ,
COALESCE(st10.end_org_area_key, stmax.END_ORG_AREA_KEY) end_org_area_key ,
COALESCE(st10.end_org_region_key,
stmax.END_ORG_REGION_KEY) end_org_region_key ,
COALESCE(st10.end_org_channel_key,
stmax.END_ORG_CHANNEL_KEY) end_org_channel_key ,
COALESCE(st10.Cycle_Qtr, latest_cod.FIN_QTR_KEY) Cycle_Qtr ,
cod.FromDateKey ,
cod.ToDateKey
FROM #ADOWNER cod with (nolock)
INNER JOIN ( SELECT DISTINCT
DT.FIN_QTR_KEY ,
AdvertiserId ,
MAX(fromdatekey) FROMDATEKEY ,
MAX(ToDateKey) TODATEKEY
FROM ( SELECT ADV.* ,
DT.FIN_QTR_KEY END_QTR
FROM ( SELECT
AdvertiserId ,
DT.FIN_QTR_KEY STRT_QTR ,
MAX(FromDateKey) AS fromdatekey ,
MAX(ToDateKey) AS ToDateKey
FROM
#ADOWNER AO
INNER JOIN CustomerMeasurementTool.workflow.Calendar DT ON DT.DATE_KEY = AO.FromDateKey
AND FIN_QTR_KEY >= 20131
GROUP BY AdvertiserId ,
DT.FIN_QTR_KEY
) ADV
LEFT JOIN CustomerMeasurementTool.workflow.Calendar DT ON DT.DATE_KEY = ADV.ToDateKey
) AO
LEFT JOIN CustomerMeasurementTool.workflow.Calendar DT ON DT.DATE_KEY BETWEEN fromdatekey AND ToDateKey
WHERE CALENDAR_DATE <= CONVERT(DATETIME, CONVERT(VARCHAR, GETDATE()
- 1, 101))
GROUP BY FIN_QTR_KEY ,
AdvertiserId
) latest_cod ON cod.AdvertiserId = latest_cod.AdvertiserId
AND cod.FromDateKey = latest_cod.FROMDATEKEY
LEFT JOIN #ALL_CONSULATANTS_Prev st10 ON cod.SalesConsultantId = st10.end_employee_sid
AND latest_cod.FIN_QTR_KEY = st10.Cycle_Qtr
LEFT JOIN ( SELECT EHD.EMPLOYEE_SID AS END_EMPLOYEE_SID ,
EHD.ORG_TEAM_KEY AS END_ORG_TEAM_KEY ,
EHD.ORG_AREA_KEY AS END_ORG_AREA_KEY ,
EHD.ORG_REGION_KEY AS END_ORG_REGION_KEY ,
EHD.ORG_CHANNEL_KEY AS END_ORG_CHANNEL_KEY
FROM [BIStage].[dbo].[EMPLOYEE_HIST_DIM_V] EHD with (nolock)
INNER JOIN ( SELECT
EMPLOYEE_SID ,
MAX(BEGIN_DATE_KEY) AS BEGIN_DATE_KEY
FROM [BIStage].[dbo].[EMPLOYEE_HIST_DIM_V] with (nolock)
WHERE
POSITION_KEY > 0
GROUP BY EMPLOYEE_SID
) EMP ON EHD.EMPLOYEE_SID = EMP.EMPLOYEE_SID
AND EHD.BEGIN_DATE_KEY = EMP.BEGIN_DATE_KEY
) stmax ON cod.SalesConsultantId = stmax.END_EMPLOYEE_SID;
CHANGED CODE :-
I have changed the yellowed part of the code and insert new code higlighted in green as :-
-- Temp Tables to build a mini version of the Calender Table.
select * into #Mini_Cal from CustomerMeasurementTool.workflow.Calendar where FIN_QTR_KEY >= 20131
SELECT DISTINCT
DT.FIN_QTR_KEY ,
AdvertiserId ,
MAX(fromdatekey) FROMDATEKEY ,
MAX(ToDateKey) TODATEKEY into #latest_cod
FROM ( SELECT ADV.* ,
DT.FIN_QTR_KEY END_QTR
FROM ( SELECT
AdvertiserId ,
DT.FIN_QTR_KEY STRT_QTR ,
MAX(FromDateKey) AS fromdatekey ,
MAX(ToDateKey) AS ToDateKey
FROM
#ADOWNER AO
INNER JOIN #Mini_Cal DT ON DT.DATE_KEY = AO.FromDateKey
GROUP BY AdvertiserId ,
DT.FIN_QTR_KEY
) ADV
LEFT JOIN #Mini_Cal DT ON DT.DATE_KEY = ADV.ToDateKey
) AO
LEFT JOIN #Mini_Cal DT ON DT.DATE_KEY BETWEEN fromdatekey AND ToDateKey
WHERE CALENDAR_DATE <= CONVERT(DATETIME, CONVERT(VARCHAR, GETDATE()
- 1, 101))
GROUP BY FIN_QTR_KEY ,
AdvertiserId
-- Customer Table and latest advertiser with complete hierarichy details
INSERT INTO reporting.Obtain_CustAM_Hier
SELECT cod.AdvertiserId ,
cod.SalesConsultantId AS end_employee_sid ,
COALESCE(st10.end_org_team_key, stmax.END_ORG_TEAM_KEY) end_org_team_key ,
COALESCE(st10.end_org_area_key, stmax.END_ORG_AREA_KEY) end_org_area_key ,
COALESCE(st10.end_org_region_key,
stmax.END_ORG_REGION_KEY) end_org_region_key ,
COALESCE(st10.end_org_channel_key,
stmax.END_ORG_CHANNEL_KEY) end_org_channel_key ,
COALESCE(st10.Cycle_Qtr, latest_cod.FIN_QTR_KEY) Cycle_Qtr ,
cod.FromDateKey ,
cod.ToDateKey
FROM #ADOWNER cod with (nolock)
INNER JOIN #latest_cod latest_cod ON cod.AdvertiserId = latest_cod.AdvertiserId
AND cod.FromDateKey = latest_cod.FROMDATEKEY
LEFT JOIN #ALL_CONSULATANTS_Prev st10 ON cod.SalesConsultantId = st10.end_employee_sid
AND latest_cod.FIN_QTR_KEY = st10.Cycle_Qtr
LEFT JOIN ( SELECT EHD.EMPLOYEE_SID AS END_EMPLOYEE_SID ,
EHD.ORG_TEAM_KEY AS END_ORG_TEAM_KEY ,
EHD.ORG_AREA_KEY AS END_ORG_AREA_KEY ,
EHD.ORG_REGION_KEY AS END_ORG_REGION_KEY ,
EHD.ORG_CHANNEL_KEY AS END_ORG_CHANNEL_KEY
FROM [BIStage].[dbo].[EMPLOYEE_HIST_DIM_V] EHD with (nolock)
INNER JOIN ( SELECT
EMPLOYEE_SID ,
MAX(BEGIN_DATE_KEY) AS BEGIN_DATE_KEY
FROM [BIStage].[dbo].[EMPLOYEE_HIST_DIM_V] with (nolock)
WHERE
POSITION_KEY > 0
GROUP BY EMPLOYEE_SID
) EMP ON EHD.EMPLOYEE_SID = EMP.EMPLOYEE_SID
AND EHD.BEGIN_DATE_KEY = EMP.BEGIN_DATE_KEY
) stmax ON cod.SalesConsultantId = stmax.END_EMPLOYEE_SID;
Apologies for such a messy code, however if you are able to follow or understand the code (by going through highlighted rows) you will find that I have done following things:-
1. Limited the Calendar table.
2. Taken the complicated code out and put it into a temp table.
The above changes did the trick and the stored proc ran within the SLA of 6 minutes (was taking 3 hours on that fatal day).
However the query which remained unanswered is why the stored proc ran much faster in our DEV environment than compared to PROD environment.
I know I may not have given the complete info, please ask questions to solve this conundrum!
