Question

如何重写此查询以便更快地执行它？

DECLARE @CityID BIGINT = 89263

-- [ Execution  takes 10 sec]
SELECT distinct MHD.[CaxHotelId],[Name],[SupportedAPIS],[Longitude],[Latitude],[CityName],[CountryName]
                ,[CountryCode],[Star],[HotelChain],[Address],[Telephone],[Fax],[Email],[Website],MHD.[Description],[DisplayName]      
INTO #tbl
FROM [MasterHotelData] as MHD     
WHERE FK_MasterHotelCityId = @CityID  ;

-- OutPut Table 1  [ Execution  takes 3 sec, outputs 300 rows ]
SELECT CaxHotelId,Name,SupportedAPIS,Longitude,Latitude,CityName,CountryName,CountryCode,Star
    ,HotelChain,Address,Telephone,Fax,Email,Website,Description,DisplayName
FROM #tbl; 

-- OutPut Table 2 [ Execution  takes 30 sec, outputs 3000 rows ]
SELECT [Id]    
    ,MHI.[CaxHotelId]    
    ,CAST ([Url] AS VARCHAR(1000))   -- Original Size VARCHAR(MAX)
    ,CAST ([ThumbUrl] AS VARCHAR(1000))   -- Original Size VARCHAR(MAX)
    ,MHI.[UpdatedDate]    
FROM [MasterHotelImage] as MHI
INNER JOIN #tbl ON #tbl.CaxHotelId = MHI.CaxHotelId;

-- OutPut Table 3 [ Execution  takes 5 sec, outputs 5000 rows ]
SELECT [Id]    
    ,MHA.[CaxHotelId]    
    ,[AmenityName]    
    ,MHA.[Description]    
    ,MHA.[UpdatedDate]    
FROM [MasterHotelAmenity]  as MHA
INNER JOIN #tbl ON #tbl.CaxHotelId = MHA.CaxHotelId

DROP  TABLE #tbl

我已将非群集索引添加到CaxHotelId和MasterHotelAmenity的{{1}}。这个查询的总执行时间将近50秒，而我的雇主希望我在10秒内完成执行。

Answer 1

您是否需要在第一次查询中使用distinct？感觉就像你没有，所以我放弃它。如果确实需要，请尝试使用组。根据我的经验，它们通常要快得多，但这可能取决于数据。

我还要先定义临时表，在CaxHotelId列上放一个索引，然后插入其中。这可能有助于加快你的联接

如何在具有批量数据的表上优化此查询？

1 个答案: