Speed up query execution. Can we add an index or rewrite the query

Question

I've been working on this query handed to me by a developer who wanted to reduce the query execution time even further. Currently, it takes almost around 40 secs and outputs 262K records. Based on the actual execution the query cost is more towards the clustered index scan on "CacheClients". However, I am not sure if adding a non clustered covering index would benefit it. Also, I see a table scan at the extreme bottom right of the plan and as per the developer they were testing with an index on that table but they weren't able to figure out an appropriate one that can fit the criteria which is basically they would join on the id fields and run queries based on date period.

   USE [ABC]
    GO

    /****** Object:  View [report].[vw_MonthlyDealAllocations]    Script Date: 11/24/2017 9:54:10 PM ******/
    --SET ANSI_NULLS ON
    --GO

    --SET QUOTED_IDENTIFIER ON
    --GO

    --CREATE VIEW [report].[vw_MonthlyDealAllocations] as
    SELECT
      PeriodStartDate,
      PeriodEndDate,
      D.DealID,
      Dl.DealName,
      D.StageID,
      CONVERT(varchar(1), D.StageID) + ' - ' + DS.Stage Stage,
      DP.Platform,
      ISNULL(D.AllocatedOfficeID, Dl.OfficeID) AS AllocatedOfficeID,
      ISNULL(D.AllocatedDepartmentID, Dl.DepartmentID) AS AllocatedDepartmentID,
      CASE
        WHEN ISNULL(D.AllocatedDepartmentID, Dl.DepartmentID) = 1 THEN 'Investment Advisory'
        WHEN ISNULL(D.AllocatedDepartmentID, Dl.DepartmentID) = 2 THEN 'Debt/EP'
        WHEN ISNULL(D.AllocatedDepartmentID, Dl.DepartmentID) = 6 THEN 'HFF Securities'
        ELSE DM.Department
      END AS AllocatedDepartment,
      AO.Name AllocatedOffice,
      CASE
        WHEN DP.DisplayWithOffice = 1 THEN AO.Name + ' ' + DP.ShortName
        ELSE AO.Name
      END AllocatedOfficeDept,
      Dl.DepartmentID DealDepartmentID,
      DX.Department DealDepartment,
      Dl.OfficeID DealOfficeID,
      DO.Name DealOffice,
      CASE
        WHEN DP.DisplayWithOffice = 1 THEN DO.Name + ' ' + DP.ShortName
        ELSE DO.Name
      END DealOfficeDept,
      DT.DealType,
      D.OfficeAllocVolumePipeline,
      D.OfficeAllocVolumeCompleted,
      D.OfficeAllocFeePipeline,
      D.OfficeAllocFeeCompleted,
      D.OfficeAllocVolumePipelineGBP,
      D.OfficeAllocVolumeCompletedGBP,
      D.OfficeAllocFeePipelineGBP,
      D.OfficeAllocFeeCompletedGBP,
      PTG.GroupName,
      PT.PropertyType,
      CASE
        WHEN C.CountryID <> 1 THEN 'Foreign'
        ELSE R.Region
      END AS Region,
      AP.Address1,
      C.City,
      S.StateLong,
      AP.Zip,
      Investor.ClientName MSA,
      Cl.ClientName RollupMSA,
      ITI.InvestorType PrimaryInvestor,
      ITC.InvestorType PrimaryClient,
      P.FirstName + ' ' + P.LastName AS PrimaryProducer,
      I.FirstName + ' ' + I.LastName AS IL_Producer,
      D.CountDealCompleted,
      CASE Dl.isSecuritized
        WHEN 0 THEN 'No'
        WHEN 1 THEN 'Yes'
        ELSE ''
      END AS isSecuritized,
      CASE Dl.isServiced
        WHEN 0 THEN 'No'
        WHEN 1 THEN 'Yes'
        ELSE ''
      END AS isServiced,
      --QCount.QtCt,
      /*IIF (CASE
            WHEN D.isCompleted = 1 THEN D.VolumeCompleted 
            WHEN (D.isPipeline = 1 OR D.StageID = 0) THEN D.VolumePipeline 
            ELSE 0 
        END >= 50000000,1,NULL
      ) AS Over50M, */
      IIF(Dl.PortfolioID IS NOT NULL, 1, NULL) AS isPortfolio,
      --IIF (isMultitransactional.linktype IS NOT NULL,1,NULL) AS isMultiTransactional,
      DP.PlatformID,
      P.EmployeeID AS PrimaryProducerID,
      I.EmployeeID AS IL_ProducerID,
      --report.fnReportGetDealClients(D.DealID) Clients,
      --report.fnReportGetDealInvestors(D.DealID) Investors,
      DFM.FinancingMethod,
      IIF((Dl.isSecuritized = 1 AND ISNULL(ISNULL(ITID2C.InvestorType, ITI.InvestorType), 'Unknown') <> 'Agency'), 'Conduit/CMBS', ISNULL(ISNULL(ITID2C.InvestorType, ITI.InvestorType), 'Unknown')) AS InvestorType

    FROM report.MonthlyDealAllocations D
    INNER JOIN dbo.Deals Dl
      ON Dl.DealID = D.DealID
    INNER JOIN DealTypes DT
      ON DT.DealTypeID = Dl.DealTypeID
    INNER JOIN DealPlatforms DP
      ON DP.PlatformID = DT.PlatformID
    INNER JOIN DealStages DS
      ON DS.StageID = D.StageID
    LEFT JOIN Departments DM
      ON DM.DepartmentID = ISNULL(D.AllocatedDepartmentID, Dl.DepartmentID)
    LEFT JOIN Departments DX
      ON DX.DepartmentID = Dl.DepartmentID
    LEFT JOIN Offices AO
      ON AO.OfficeID = ISNULL(D.AllocatedOfficeID, Dl.OfficeID)
    LEFT JOIN Offices DO
      ON DO.OfficeID = Dl.OfficeID
    LEFT JOIN dbo.DealProperties DPP
      ON D.DealID = DPP.DealID
      AND DPP.IsMainProperty = 1
    LEFT JOIN PropertyTypes PT
      ON PT.PropertyTypeID = DPP.PropertyTypeID
    LEFT JOIN PropertyTypeGroups PTG
      ON PTG.GroupID = PT.GroupID
    LEFT JOIN DealProperties AS DPZ
      ON D.DealID = DPZ.DealID
      AND DPZ.isMainProperty = 1
    LEFT JOIN Assets AP
      ON DPZ.AssetID = AP.AssetID
    LEFT JOIN Cities C
      ON C.CityID = AP.CityID
    LEFT JOIN States S
      ON S.StateID = C.StateID
    LEFT JOIN Regions R
      ON ISNULL(C.RCARegionID, ISNULL(S.RCARegionID, S.RegionID)) = R.RegionID
    LEFT JOIN DealsToClients DTCC
      ON D.DealID = DTCC.DealID
      AND DTCC.isPrimary = 1
      AND DTCC.MemberType IN (1, 3)
    LEFT JOIN DealsToClients DTCI
      ON D.DealID = DTCI.DealID
      AND DTCI.isPrimary = 1
      AND DTCI.MemberType IN (2, 4)
    LEFT JOIN CacheClients Cl
      ON DTCC.ClientID = Cl.ClientID
    LEFT JOIN CacheClients Investor
      ON DTCI.ClientID = Investor.ClientID
    LEFT JOIN InvestorTypes ITI
      ON Investor.InvestorTypeID = ITI.InvestorTypeID
    LEFT JOIN InvestorTypes ITC
      ON Cl.InvestorTypeID = ITC.InvestorTypeID
    --LEFT JOIN (SELECT DISTINCT D2D.DealID, D2D.LinkType FROM DealsToDeals D2D WHERE LinkType = 2) isMultitransactional ON D.DealID = isMultitransactional.DealID 
    LEFT JOIN DealsToEmployees EP
      ON D.DealID = EP.DealID
      AND EP.MemberType = 1
      AND EP.isPrimary = 1
    LEFT JOIN DealsToEmployees EI
      ON D.DealID = EI.DealID
      AND EI.MemberType = 2
      AND EI.isPrimary = 1
    LEFT JOIN Employees P
      ON EP.EmployeeID = P.EmployeeID
    LEFT JOIN Employees I
      ON EI.EmployeeID = I.EmployeeID
    LEFT JOIN DealFinancingMethods DFM
      ON Dl.DealFinancingMethodID = DFM.DealFinancingMethodsID
    LEFT JOIN InvestorTypes AS ITID2C
      ON DTCI.InvestorTypeID = ITID2C.InvestorTypeID
    --LEFT JOIN (SELECT DealID, COUNT(QuoteID) AS QtCt FROM Quotes WHERE DateRemoved IS NULL GROUP BY DealID) QCount ON D.dealid = Qcount.DealID 
 go

Below is the index they created.

USE [ABC]
GO

/****** Object:  Index [IX_MonthlyDealAllocations_DealID_AllocDeptID_AllocOfficeID]    Script Date: 11/24/2017 11:43:00 PM ******/
CREATE NONCLUSTERED INDEX [IX_MonthlyDealAllocations_DealID_AllocDeptID_AllocOfficeID] ON [report].[MonthlyDealAllocations]
(
    [DealID] ASC,
    [AllocatedDepartmentID] ASC,
    [AllocatedOfficeID] ASC
)
INCLUDE (   [PeriodStartDate],
    [PeriodEndDate],
    [CountDealCompleted],
    [StageID]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

Execution plan link https://www.brentozar.com/pastetheplan/?id=SJu_XK8lM

SQL Script file (Includes schema and index DDL) https://pastebin.com/BB8p9hqa

Answer 1

If you run your query with SET STATISTICS IO ON; that'll give you information about IO required for all of your joined tables. Based on estimated plan costs you'll get the most benefit from adding a covering index on the CacheClients table. That table has around 50 columns but you only use three columns in your query. Creating an index on ClientID, ClientName, and InvestorTypeID will reduce IO requirements for that table because SQL Server will be able to scan the index that contains only those three columns instead of the full table. You will see benefits even if the join type doesn't change.

Other than that there's not a lot going here. Your cardinality estimate starting at MonthlyDealAllocations never changes, so it's not like you should be joining to a specific table first to improve performance. If possible, changing some of the joins expected to change cardinality to LEFT OUTER JOINS or defining unique indexes on some of the tables could improve your estimates to keep them at a constant 262336 throughout the plan. This could have a minor benefit in avoiding the tempdb spill at node id 61.

If you're really desperate you could try a MAXDOP 1 hint or disabling MERGE JOINS via OPTION (LOOP JOIN, HASH JOIN) just to see what happens to the query's runtime. As is you're asking for data from a bunch of different tables and SQL Server is going to take time to do all of those joins. There's no magic query rewrite that's going to change that. I recommend approaching this problem by defining a minimum acceptable query performance time target instead of just wanting to make it faster without a concrete goal in mind.

Answer 2

Your Query is simple and lengthy.

i) you need minor correction in your query.Hope your query is giving correct output.Also hope all other left join are justified.

LEFT JOIN Departments DM
      ON DM.DepartmentID = ISNULL(D.AllocatedDepartmentID, Dl.DepartmentID)
    LEFT JOIN Departments DX
      ON DX.DepartmentID = Dl.DepartmentID

This can be written as,

LEFT JOIN Departments DM
      ON DM.DepartmentID = D.AllocatedDepartmentID
    LEFT JOIN Departments DX
      ON DX.DepartmentID = Dl.DepartmentID

LEFT JOIN Offices AO
      ON AO.OfficeID = ISNULL(D.AllocatedOfficeID, Dl.OfficeID)
    LEFT JOIN Offices DO
      ON DO.OfficeID = Dl.OfficeID

Rewrite it as,

LEFT JOIN Offices AO
      ON AO.OfficeID = D.AllocatedOfficeID
    LEFT JOIN Offices DO
      ON DO.OfficeID = Dl.OfficeID

Replace this line with,

LEFT JOIN Cities C
      ON C.CityID = AP.CityID
    LEFT JOIN States S
      ON S.StateID = C.StateID
    LEFT JOIN Regions R
      ON ISNULL(C.RCARegionID, ISNULL(S.RCARegionID, S.RegionID)) = R.RegionID


LEFT JOIN Cities C
      ON C.CityID = AP.CityID
    LEFT JOIN States S
      ON S.StateID = C.StateID
    LEFT JOIN Regions R
      ON R.RegionID=C.RCARegionID
      LEFT JOIN Regions R1
      R1.RegionID=(S.RCARegionID and S.RCARegionID is not NULL) or (S.RegionID and S.RCARegionID is  NULL)) 

MAXDOP : I do not have much knowledge on MAXDOP.your current MAXDOP is 4.if it is reduce to MAXDOP=2 through query HINT then there might be boost in speed.I am not sure at the same time.

Index : IMHO,you should drop your existing composite NON CI on MonthlyDealAllocations,becasue composite index do not work in this manner.Create seperate NON CI for each and keep one covering index.Why there is no CI in MonthlyDealAllocations .if there is any CI and it us being use then no need of covering index.

Also there should be index on each table which has more than 400 rows.I am not sure about number.