Query optimizaton - Suggestions

  • I Need help in optimizing the query ,

    Could you please throw some techniques or any valid query for replacement of this query . Help is highly appreciated as i am in dead lock to finish this .

    SELECT Distinct Systems.SiteNumber AS 'SiteNumber',

    PolicyAudit.PolicyID AS 'PolicyID',

    PolicyAudit.ERNExemptFlag AS 'ERNExemptFlag',

    CONVERT(VARCHAR(8), PolicyAudit.LastModifiedDate, 112) AS 'DateSent'

    FROM PolicyAudit

    LEFT JOIN Systems ON Systems.ID = PolicyAudit.SourceSystemID

    OUTER APPLY (SELECT Top(1) pa.HasERN,

    st.SiteNumber,

    pa.PolicyID,

    CONVERT(VARCHAR(8), pa.LastModifiedDate, 112) as 'DateSent1' ,

    ERNExemptFlag

    FROM PolicyAudit pa

    LEFT JOIN Systems st ON st.ID = pa.SourceSystemID

    WHERE rtrim(ltrim(pa.PolicyID)) =PolicyAudit.PolicyID

    And pa.Status=1

    Order By pa.ID desc ) Derived_Policy_Audit_Latest

    WHERE PolicyAudit.Status =1

    AND PolicyAudit.HasERN = 0

    AND Systems.FileTypeIndicator in ('C','V')

    and PolicyAudit.policyid=Derived_Policy_Audit_Latest.policyid

    and CONVERT(VARCHAR(8), PolicyAudit.LastModifiedDate, 112)=Derived_Policy_Audit_Latest.DateSent1

    and Systems.SiteNumber=Derived_Policy_Audit_Latest.SiteNumber

    and Derived_Policy_Audit_Latest.HasERN=0

  • mbavabohrude (4/22/2016)


    I Need help in optimizing the query ,

    Could you please throw some techniques or any valid query for replacement of this query . Help is highly appreciated as i am in dead lock to finish this .

    SELECT Distinct Systems.SiteNumber AS 'SiteNumber',

    PolicyAudit.PolicyID AS 'PolicyID',

    PolicyAudit.ERNExemptFlag AS 'ERNExemptFlag',

    CONVERT(VARCHAR(8), PolicyAudit.LastModifiedDate, 112) AS 'DateSent'

    FROM PolicyAudit

    LEFT JOIN Systems ON Systems.ID = PolicyAudit.SourceSystemID

    OUTER APPLY (SELECT Top(1) pa.HasERN,

    st.SiteNumber,

    pa.PolicyID,

    CONVERT(VARCHAR(8), pa.LastModifiedDate, 112) as 'DateSent1' ,

    ERNExemptFlag

    FROM PolicyAudit pa

    LEFT JOIN Systems st ON st.ID = pa.SourceSystemID

    WHERE rtrim(ltrim(pa.PolicyID)) =PolicyAudit.PolicyID

    And pa.Status=1

    Order By pa.ID desc ) Derived_Policy_Audit_Latest

    WHERE PolicyAudit.Status =1

    AND PolicyAudit.HasERN = 0

    AND Systems.FileTypeIndicator in ('C','V')

    and PolicyAudit.policyid=Derived_Policy_Audit_Latest.policyid

    and CONVERT(VARCHAR(8), PolicyAudit.LastModifiedDate, 112)=Derived_Policy_Audit_Latest.DateSent1

    and Systems.SiteNumber=Derived_Policy_Audit_Latest.SiteNumber

    and Derived_Policy_Audit_Latest.HasERN=0

    Technique #1: please include the actual execution plan and DDL for the tables from are selecting from in your performance-related posts 🙂

    The absence of evidence is not evidence of absence
    - Martin Rees
    The absence of consumable DDL, sample data and desired results is, however, evidence of the absence of my response
    - Phil Parkin

  • Technique #2: Make your query readable by using indentation and code="sql" tags:

    SELECT DISTINCT

    Systems.SiteNumber AS 'SiteNumber'

    , PolicyAudit.PolicyID AS 'PolicyID'

    , PolicyAudit.ERNExemptFlag AS 'ERNExemptFlag'

    , CONVERT(VARCHAR(8), PolicyAudit.LastModifiedDate, 112) AS 'DateSent'

    FROM PolicyAudit

    LEFT JOIN Systems ON Systems.ID = PolicyAudit.SourceSystemID

    OUTER APPLY (SELECT TOP (1)

    pa.HasERN

    , st.SiteNumber

    , pa.PolicyID

    , CONVERT(VARCHAR(8), pa.LastModifiedDate, 112) AS 'DateSent1'

    , ERNExemptFlag

    FROM PolicyAudit pa

    LEFT JOIN Systems st ON st.ID = pa.SourceSystemID

    WHERE RTRIM(LTRIM(pa.PolicyID)) = PolicyAudit.PolicyID

    AND pa.Status = 1

    ORDER BY pa.ID DESC

    ) Derived_Policy_Audit_Latest

    WHERE PolicyAudit.Status = 1

    AND PolicyAudit.HasERN = 0

    AND Systems.FileTypeIndicator IN ('C', 'V')

    AND PolicyAudit.policyid = Derived_Policy_Audit_Latest.policyid

    AND CONVERT(VARCHAR(8), PolicyAudit.LastModifiedDate, 112) = Derived_Policy_Audit_Latest.DateSent1

    AND Systems.SiteNumber = Derived_Policy_Audit_Latest.SiteNumber

    AND Derived_Policy_Audit_Latest.HasERN = 0;

    The absence of evidence is not evidence of absence
    - Martin Rees
    The absence of consumable DDL, sample data and desired results is, however, evidence of the absence of my response
    - Phil Parkin

  • 1) Have you done a file IO stall analysis or wait stats analysis while the code is running to see why it is slow? sp_whoisactive has a differential parameter

    2) You have two functions around columns in WHERE clauses. Those have to go.

    3) Have you checked for mismatched column data types you are joining?

    4) Check the query plan for huge mismatches between estimated and actual rows.

    5) How up to date are the statistics in the tables involved?

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

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