SQL Server，带有截断的临时表与带有删除的表变量 [英] SQL Server, temporary tables with truncate vs table variable with delete

问题描述

我有一个存储过程，我在其中创建了一个通常包含 1 到 10 行的临时表.该表在存储过程中被多次截断和填充.它被截断，因为这比删除快.当我因使用删除而受到惩罚时，我是否通过用表变量替换这个临时表来获得任何性能提升(截断不适用于表变量)

I have a stored procedure inside which I create a temporary table that typically contains between 1 and 10 rows. This table is truncated and filled many times during the stored procedure. It is truncated as this is faster than delete. Do I get any performance increase by replacing this temporary table with a table variable when I suffer a penalty for using delete (truncate does not work on table variables)

虽然表变量主要在内存中并且通常比临时表快，但我是否因为必须删除而不是截断而失去任何好处?

Whilst table variables are mainly in memory and are generally faster than temp tables do I loose any benefit by having to delete rather than truncate?

推荐答案

运行以下脚本，看起来表变量是更好的选择

Running the followign to scripts, it would seem that the Table Variable is the better option

CREATE TABLE #Temp(
        ID INT
)

DECLARE @Int INT,
        @InnerInt INT
SELECT  @Int = 1,
        @InnerInt = 1

WHILE @Int < 50000
BEGIN
    WHILE @InnerInt < 10
    BEGIN
        INSERT INTO #Temp SELECT @InnerInt
        SET @InnerInt = @InnerInt + 1
    END
    SELECT @Int = @Int + 1,
            @InnerInt = 1
    TRUNCATE TABLE #Temp
END

DROP TABLE #TEMP

GO

DECLARE @Temp TABLE(
        ID INT
)

DECLARE @Int INT,
        @InnerInt INT
SELECT  @Int = 1,
        @InnerInt = 1

WHILE @Int < 50000
BEGIN
    WHILE @InnerInt < 10
    BEGIN
        INSERT INTO @Temp SELECT @InnerInt
        SET @InnerInt = @InnerInt + 1
    END
    SELECT @Int = @Int + 1,
            @InnerInt = 1
    DELETE FROM @Temp
END

来自 Sql Profiler

From Sql Profiler

CPU     Reads   Writes  Duration
36375     2799937   0       39319

vs

CPU     Reads   Writes  Duration
14750   1700031 2       17376   

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