EXISTS子句的SQL Server查询提示

Question

我正在尝试强制SQL服务器使用hash match for exists子句，如下所示。

Execution Plan

FROM 
    [Dbo].[360 Nrc Data] AS [nrc]
WHERE 
    [CALENDAR_DATE] BETWEEN @START_DATE AND @End_Date
    AND EXISTS (SELECT 1
                FROM [staging].[FACT_DTV_RETENTION_EVENT_STEP_1] AS [fact]
                WHERE [fact].[CD_PORTFOLIO_ID] = [nrc].[Cd_Portfolio_Id]
                  AND [fact].[Event_Date] = [nrc].[CALENDAR_DATE])
GROUP BY 
    [Calendar_Date], [Cd_Portfolio_Id])

强制查询提示的常规方法如下所示，但Left Semi Join比join

更有效

[_fact_date_and_portfolio] AS [fact]    
     inner hash join    

     [dbo].[360 TA Offer] AS [offr]

Answer 1

没有提示语法来指定特定半连接或反半连接运算符的物理连接类型。

但是由于此计划只有一个联接，您只需将OPTION (HASH JOIN)添加到查询的末尾即可。提示适用于所有连接，但没有任何其他连接。