Question

我在1700万条记录表上使用了光标。它真的很慢，比方说每秒30发。我不知道从哪里开始。

它将1个表中的所有数据传输到多个表中，每个表每年都有数据。

以下是代码：

CREATE PROCEDURE [dbo].[Importer2]
AS
BEGIN
    SET NOCOUNT ON;

    DECLARE @LogId bigint;
    DECLARE @SensorID int;
    DECLARE @ValueNumeric decimal(12,4);
    DECLARE @ValueString nvarchar(20);
    DECLARE @DateAdded datetime;
    DECLARE @Status_ NVARCHAR(10)
    DECLARE @SQLString_ NVARCHAR(MAX)
    DECLARE @Year_  NVARCHAR(4)
    DECLARE @TableName_ NVARCHAR(100) --= '[ScadaData].[dbo].[2016_123456]'
    DECLARE @TableNameOnly_ NVARCHAR(100)
    DECLARE @ValueStringTMP_ NVARCHAR(20)
    DECLARE @Measure_ datetime

    DECLARE @ImporterCursor AS CURSOR;

    SET @Status_ = 'OK'

    SELECT @LogId = Value 
    FROM dbo.AppSettings  
    WHERE dbo.AppSettings.Setting = 'LastImportedId';

    SET @ImporterCursor = CURSOR FAST_FORWARD FOR
        SELECT * 
        FROM dbo.Logs l 
        WHERE l.LogID > @LogId;

    OPEN @ImporterCursor;

    FETCH NEXT FROM @ImporterCursor INTO @LogId, @SensorID, @ValueNumeric, @ValueString, @DateAdded;

    WHILE @@FETCH_STATUS = 0
    BEGIN
        IF (@DateAdded IS NOT null)
        BEGIN
            SET @TableName_ = '[ScadaData].[dbo].[Y' + CONVERT(varchar,YEAR(@DateAdded)) + 'S' + CONVERT(varchar,@SensorID) + ']'
            SET @TableNameOnly_ = 'Y' + CONVERT(varchar,YEAR(@DateAdded)) + 'S' + CONVERT(varchar,@SensorID)

            --table does not exists. Create one
            IF NOT EXISTS (SELECT 1 FROM ScadaData.dbo.sysobjects 
                           WHERE xtype = 'U' AND name = @TableNameOnly_)
            BEGIN
                SET @SQLString_ = 'CREATE TABLE ' + @TableName_ + '(
                    [LogID] [bigint] IDENTITY(1,1) NOT NULL,
                    [ValueNumeric] [decimal](12, 4) NULL,
                    [ValueString] [nvarchar](20) NULL,
                    [DateAdded] [datetime2](7) NULL DEFAULT (GETUTCDATE()),
                    CONSTRAINT [PK_Logs' + @TableNameOnly_ + '] PRIMARY KEY CLUSTERED ([LogID] ASC) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY];
                    CREATE NONCLUSTERED INDEX [DateAddedDESC_' + @TableNameOnly_ + '] ON [dbo].[' + @TableNameOnly_ + '] ([DateAdded] DESC) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON);'

            EXEC sp_executesql @SQLString_
        END

        --Insert or Update if ValueNumeric is sent
        IF @ValueNumeric IS NOT NULL
        BEGIN
            SET @SQLString_ =               'DECLARE @ValueNumericTmp_  DECIMAL(12,4);'
            SET @SQLString_ = @SQLString_ + 'DECLARE @LogID             BIGINT;'
            SET @SQLString_ = @SQLString_ + 'SELECT TOP 1 @ValueNumericTmp_ = ValueNumeric, @LogID = LogID FROM ' + @TableName_ + ' ORDER BY DateAdded DESC;'
            SET @SQLString_ = @SQLString_ + 'IF (@ValueNumericTmp_ = ' + CONVERT(varchar, @ValueNumeric) + ')'
            SET @SQLString_ = @SQLString_ + '   UPDATE ' + @TableName_ + ' SET DateAdded = ''' + CONVERT(varchar,@DateAdded,121) + ''' WHERE LogID = @LogID;'
            SET @SQLString_ = @SQLString_ + 'ELSE'
            SET @SQLString_ = @SQLString_ + '   INSERT INTO ' + @TableName_ + ' (ValueNumeric, ValueString, DateAdded) VALUES (' + CONVERT(varchar,@ValueNumeric) +', ' + ISNULL(''''  + @ValueString + '''','NULL') + ', GETUTCDATE());'

            EXEC (@SQLString_)
        END

        --Insert or Update if ValueString is sent
        IF @ValueString IS NOT NULL
        BEGIN
            SET @SQLString_ =               'DECLARE @ValueStringTMP_   NVARCHAR(20);'
            SET @SQLString_ = @SQLString_ + 'DECLARE @LogID             BIGINT;'
            SET @SQLString_ = @SQLString_ + 'SELECT TOP 1 @ValueStringTMP_ = ValueString, @LogID = LogID FROM ' + @TableName_ + ' ORDER BY DateAdded DESC;'
            SET @SQLString_ = @SQLString_ + 'IF (@ValueStringTMP_ = ''' + @ValueString + ''')'
            SET @SQLString_ = @SQLString_ + '   UPDATE ' + @TableName_ + ' SET DateAdded = ''' + CONVERT(varchar,@DateAdded,121) + ''' WHERE LogID = @LogID;'
            SET @SQLString_ = @SQLString_ + 'ELSE'
            SET @SQLString_ = @SQLString_ + '   INSERT INTO ' + @TableName_ + ' (ValueNumeric, ValueString, DateAdded) VALUES (' + CONVERT(varchar,@ValueNumeric) +', ''' + @ValueString + ''', GETUTCDATE());'

            EXEC sp_executesql @SQLString_
        END
    END

    UPDATE dbo.AppSettings 
    SET dbo.AppSettings.[Value] = CAST(@LogId AS VARCHAR (50)) 
    WHERE dbo.AppSettings.Setting = 'LastImportedId';

   FETCH NEXT FROM @ImporterCursor INTO @LogId, @SensorID, @ValueNumeric, @ValueString, @DateAdded;
    END

    CLOSE @ImporterCursor;
    DEALLOCATE @ImporterCursor;
END

Answer 1

你有很多问题如前所述，第一个红旗是光标但是，有时你不能在没有光标的情况下支持逻辑，这是你的理由。

其次，您使用动态SQL。它也有助于提高绩效。

但是，你最大的问题是应用程序设计您不得从日志中为每个传感器创建单独的表。

简单的解决方案是创建仅一个＆＃34; tbl_Sensors＆＃34;带有附加列SensorID的表，并重复使用1700次，而不是重新创建1700个表。

SQL Server存储过程非常慢

1 个答案: