Faster Querying

  • Hi Everyone,

    Total records : 2,50,0000.

    select A.C1,

    Max(DateDiff(D, Coalesce (Date1,Date2,Date3),Getdate())),

    from T1 as A

    Join T2 B on A.rnum = B.rnum and A.lnum = B.lnum AND A.type = 'L'

    GROUP BY A.C1

    I have got non clustered index on C1

    I want to query data as fast as i can, Please have a look and let me..Thanks in advance.

  • suggest you read this and then post back again.

    http://www.sqlservercentral.com/articles/SQLServerCentral/66909/

    ________________________________________________________________
    you can lead a user to data....but you cannot make them think
    and remember....every day is a school day

  • Yes, please review that article...and then upload your current execution plan. Just guessing, but you'll most like have a clustered index scan on T1 and T2 (unless it's a heap).

    Maybe you might want to try creating a non clustered index on T1 using RootNum, LineNum, and Type as key columns, and C1, Date_Physician_Reviewed, Date_Nurse_Reviewed, CODER_RVWD_DT as included columns.

    And consider something similar to T2 as the JOIN hits the same columns in T2 (for RootNum, LineNum)

    ______________________________________________________________________________Never argue with an idiot; Theyll drag you down to their level and beat you with experience

  • Reformatted your code to read it easier:

    select

    A.C1,

    Max(DateDiff(D, Coalesce (Date_Physician_Reviewed,Date_Nurse_Reviewed,CODER_RVWD_DT),Getdate())),

    'MN QA REPORT - PASSED RECONSIDERATION REPAYMENT'

    from

    T1 as A

    Join T2 B

    on A.Rootnum = B.rootnum

    and A.linenum = B.linenum

    AND A.type = 'L'

    GROUP BY

    A.C1

    The only columns that I know belong to a specific table are the columns that you prefixed with table aliases. The tables in the COALESCE function I have no idea which table they come from so hard to tell you much regarding them.

    I could see an index on RootNum, LineNum, Type on table T1 and RootNum, LineNum on table T2. With as few columns being returned I would add the columns C1 from T1 to that index and the columns Date_Physician_Reviewed, Date_Nurse_Reviewed, CODER_RVWD_DT to the aapropriate indexes on which ever table they reside.

    Want or need more? You need to post more information. In this case you should read the second article I reference below in my signature block.

  • Thank you everyone for your valuable reply.i have created indexes and its working fine.Thanks

  • Awesome, glad it worked.

    ______________________________________________________________________________Never argue with an idiot; Theyll drag you down to their level and beat you with experience

  • What you really need to do first is add the best clustered index to both tables. Then and only then do you add other, non-clustered, covering indexes if they are still required.

    SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".

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