SQL DB腳本性能調優

Question

我需要解決prod數據庫問題以及花費了很長時間的清理腳本。 我嘗試了幾件事卻沒有任何運氣，以下是腳本：

DECLARE @ErrorMessage NVARCHAR(4000)
DECLARE @ErrorSeverity INT
DECLARE @ErrorState INT
DECLARE @ErrorProcedure NVARCHAR(50)

BEGIN TRY

    IF OBJECT_ID('tempdb..#SuspectData') IS NOT NULL
    BEGIN
        DROP TABLE #SuspectData 
    END

    CREATE TABLE #SuspectData
      (
          IID INT,
          CID INT,
          PID INT
      )

    INSERT INTO dbo.#SuspectData 
    SELECT DL.IID,DL.CID,IT.PID FROM DL
    INNER JOIN IT ON IT.CID = DL.CID AND IT.IID = DL.IID
    WHERE DL.Suspect = 1


    WHILE (1 = 1)
    BEGIN
        BEGIN TRANSACTION

        UPDATE TOP (5000) TDS
        SET TDS.DTID = 4 
        FROM 
        TDS
        INNER JOIN dbo.#SuspectData SD
        ON TDS.IID = SD.IID AND TDS.PID = SD.PID
        WHERE TDS.DTID <> 4

       IF @@ROWCOUNT = 0
       BEGIN
          COMMIT TRANSACTION
          BREAK
       END

       COMMIT TRANSACTION
    END

    WHILE (1 = 1)
    BEGIN
        BEGIN TRANSACTION

        UPDATE TOP (5000) TDA
        SET TDA.DTID = 4 
        FROM 
        TDA
        INNER JOIN dbo.#SuspectData SD
        ON TDA.IID = SD.IID AND TDA.PID = SD.PID
        WHERE TDA.DTID <> 4

        IF @@ROWCOUNT = 0
        BEGIN
          COMMIT TRANSACTION
          BREAK
        END

       COMMIT TRANSACTION
    END

    DROP TABLE #SuspectData

END TRY

BEGIN CATCH

    SELECT  @ErrorMessage = ERROR_MESSAGE(),
            @ErrorSeverity = ERROR_SEVERITY(),
            @ErrorState = ERROR_STATE(),
            @ErrorProcedure = ERROR_PROCEDURE()

    RAISERROR (@ErrorMessage,@ErrorSeverity,@ErrorState,@ErrorProcedure) ;

END CATCH

我還具有以下腳本來同時更新所有內容，但是這也要花費很長時間，例如24小時左右。

DECLARE @ErrorMessage NVARCHAR(4000)
DECLARE @ErrorSeverity INT
DECLARE @ErrorState INT
DECLARE @ErrorProcedure NVARCHAR(50)

BEGIN TRY

    IF OBJECT_ID('tempdb..#SuspectData') IS NOT NULL
    BEGIN
        DROP TABLE #SuspectData 
    END

    CREATE TABLE #SuspectData
      (
          IID INT,
          CID INT,
          PID INT
      )

    INSERT INTO dbo.#SuspectData 
    SELECT DL.IID,DL.CID,IT.PID FROM DL
    INNER JOIN IT ON IT.CID = DL.CID AND IT.IID = DL.IID
    WHERE DL.Suspect = 1

    BEGIN TRANSACTION

        --Update about 1.5M records
        UPDATE TDS
        SET TDS.DTID = 4 
        FROM 
        TDS
        INNER JOIN dbo.#SuspectData SD
        ON TDS.IID = SD.IID AND TDS.PID = SD.PID
        WHERE TDS.DTID <> 4

    COMMIT TRANSACTION

    BEGIN TRANSACTION

        --Update about 4.5M records
        UPDATE TDA
        SET TDA.DTID = 4 
        FROM 
        TDA
        INNER JOIN dbo.#SuspectData SD
        ON TDA.IID = SD.IID AND TDA.PID = SD.PID
        WHERE TDA.DTID <> 4

    COMMIT TRANSACTION

    DROP TABLE #SuspectData

END TRY

BEGIN CATCH

    SELECT  @ErrorMessage = ERROR_MESSAGE(),
            @ErrorSeverity = ERROR_SEVERITY(),
            @ErrorState = ERROR_STATE(),
            @ErrorProcedure = ERROR_PROCEDURE()

    RAISERROR (@ErrorMessage,@ErrorSeverity,@ErrorState,@ErrorProcedure) ;

END CATCH

Answer 1

我猜TDS表很大。 在這種情況下，可以通過在臨時表上創建索引來加快臨時表和TDS之間的聯接操作（在TDS.IID = SD.IID和TDS.PID = SD.PID上）：

任一主要群集：

CREATE TABLE #SuspectData
      (
          IID INT,
          CID INT,
          PID INT,
          CONSTRAINT pk_temp PRIMARY KEY(IID, PID)
      )

或非群集（如果IID-PID對不是唯一的）：

CREATE INDEX IDX_Temp_SuspectData ON #SuspectData(IID,PID)

您還可以做的是檢查那些查詢的執行計划-這將幫助您找到需要花費很長時間的操作。 側面：如果可以避免的話，我通常不建議使用游標。

Answer 2

首先，是否有什么可以將DL.Suspect = 1更改為其他內容？ 還是您的數據集越來越大？

我也同意肖恩·蘭格（Sean Lange）的觀點，是全部更新還是全部刪除？

我建議使用游標 。 游標是拆分大型事務以加快使用速度並減少表鎖定的好方法。

DECLARE db_cursor CURSOR FOR SELECT DL.IID,DL.CID,IT.PID FROM DL
                            INNER JOIN IT ON IT.CID = DL.CID AND IT.IID = DL.IID
                            WHERE DL.Suspect = 1; 
DECLARE @first INT;
DECLARE @second INT;
DECLARE @third INT;
OPEN db_cursor;
FETCH NEXT FROM db_cursor INTO @first , @second , @third ;
WHILE @@FETCH_STATUS = 0  
BEGIN  
      -- Do your updates one row at a time here
      UPDATE TDS
    SET TDS.DTID = 4 
    FROM TDS
    WHERE TDS.IID = @first AND TDS.PID = @third
    WHERE TDS.DTID <> 4
END;
CLOSE db_cursor;
DEALLOCATE db_cursor;