需要減少查詢時間

Question

我的問題是下面的查詢需要38秒完成， 我需要儘可能減少這個時間。 當我查看執行計劃：Dim_Customers索引掃描的％54花費。 任何建議，將不勝感激。由於

DECLARE @SalesPersonCode NVARCHAR(4) 
DECLARE @StartDate  DATETIME 
DECLARE @EndDate   DATETIME 

SET @SalesPersonCode = 'AC'; 
SET @StartDate  = '03/01/2012'; 
SET @endDate   = '03/31/2012'; 

SELECT AA_FactSalesOrderDetails.Salesperson 
      , Dim_SalesOrganisation.[Salesperson name] 
      , AA_FactSalesOrderDetails.[Order Date] 
      , Dim_Customers.[Customer number] 
      , Dim_Customers.[Customer name] 
      , Dim_Customers.[Area/state] 
      , Dim_Customers.country 
      , Dim_Customers.[Customer stop] AS [Customer Block] 
      , AA_FactSalesOrderDetails.[Customer order stop] AS [Co Stop] 
      , AA_FactSalesOrderDetails.[First delivery date Header] 
      , AA_FactSalesOrderDetails.[Last delivery date Header] 
      , Dim_Customers.[User-defined field 6 - customer] 
      , Dim_Customers.[Customer group name] 
      , AA_FactSalesOrderDetails.[Contact Method] 
      , AA_FactSalesOrderDetails.[Customer order number] 
      , AA_FactSalesOrderDetails.[Price Level] 
      , AA_FactSalesOrderDetails.[Item number] 
      , Dim_Items.[Product group description] AS [Item name] 
      , AA_FactSalesOrderDetails.[Ordered quantity - basic U/M] AS [Quantity Ordered] 
      , AA_FactSalesOrderDetails.[Ordered quantity - basic U/M] * AA_FactSalesOrderDetails.[Net price] AS [Order Line Total ] 

FROM AA_FactSalesOrderDetails 
    LEFT JOIN 
    Dim_SalesOrganisation 
    ON 
    AA_FactSalesOrderDetails.Salesperson = Dim_SalesOrganisation.Salesperson 
    LEFT JOIN 
    Dim_Customers 
    ON 
    AA_FactSalesOrderDetails.Dim_Customers_dKey = Dim_Customers.Dim_Customers_dKey 
    LEFT JOIN 
    Dim_Items 
    ON 
    AA_FactSalesOrderDetails.[Item number] = Dim_Items.[Item number] 
    LEFT JOIN 
    Dim_CustomerOrderTypes 
    ON 
    AA_FactSalesOrderDetails.[Customer order type] = Dim_CustomerOrderTypes.[Customer order type] 



WHERE AA_FactSalesOrderDetails.[Order Date] 
     BETWEEN 
     dbo.fnc_M3_sql_datetime_to_M3_date(@StartDate) /* !!!Procedural Approach!!! */ 
     AND 
     dbo.fnc_M3_sql_datetime_to_M3_date(@EndDate)  /* !!!Procedural Approach!!! */ 
     AND 
     AA_FactSalesOrderDetails.Salesperson = @SalesPersonCode 

Answer 1

由於fnc_M3_sql_datetime_to_M3_date取一個值，在整個查詢的執行恆定的，移動這兩個電話（具有的startDate和一個與結束日期到您的查詢的頂部，將返回的值聲明的變量，然後引用這些聲明的變量下方，而不是調用where子句中的功能，這可能會有幫助。功能有時會阻礙一個很好的查詢計劃的制定。

這談論它 Why do SQL Server Scalar-valued functions get slower? 這也太有點 http://strictlysql.blogspot.com/2010/06/scalar-functions-on-where-clause.html

declare @m3StartDate Numeric(8,0) 
Set @m3StartDate = fnc_M3_sql_datetime_to_M3_date(@StartDate) 
declare @m3EndDate Numeric(8,0) 
Set @m3EndDate = fnc_M3_sql_datetime_to_M3_date(@EndDate) 
... 
WHERE AA_FactSalesOrderDetails.[Order Date] 
     BETWEEN @m3StartDate AND @m3EndDate 
     AND 
     AA_FactSalesOrderDetails.Salesperson = @SalesPersonCode 

兩個@ m3-vars的類型應該與AA_FactSalesOrderDetails完全相同。[Order Date]。

我還會檢查Dim_Customers中正在獲取掃描而不是查找的鍵的定義，並確保Dim_Customers索引的方式可以幫助您，如果它尚未。 http://blog.sqlauthority.com/2009/08/24/sql-server-index-seek-vs-index-scan-diffefence-and-usage-a-simple-note/

Answer 2

我願意賭錢這個版本運行速度超過35秒。

現在，仍然可能會有其他優化（例如創建或改進索引，如果沒有看到該計劃，我們無法知道這些索引），但我想我已經清理了查詢中應該協助性能的幾個問題。

編輯，因爲顯然用戶運行的是針對2000即使問題被標記2008年的幾個編輯...

-- make sure you don't have an implicit conversion between varchar and nvarchar 
DECLARE 
    @SalesPersonCode NVARCHAR(4), 
    @StartDate DATETIME, 
    @EndDate DATETIME; 

SELECT 
    @SalesPersonCode = N'AC', -- nvarchar needs N prefix! 
-- get rid of the function call, I am guessing it just removes time 
-- in which case, use the DATE data type instead. 
    @StartDate  = '20120301', 
    @EndDate   = '20120331'; 

-- since a salesperson can only have one code, and you are only pulling the name into the 
-- SELECT list (it will be the same for every row), use a constant and eliminate the join. 

DECLARE @SalesPersonName NVARCHAR(255); 

SELECT @SalesPersonName = SalesPerson_Name 
    FROM dbo.Dim_SalesOrganisation 
    WHERE SalesPerson = @SalesPersonCode; 

-- I've added table aliases which make the query MUCH, MUCH easier to read 

SELECT f.Salesperson 
    , Salesperson_name = @SalesPersonName 
    , f.[Order Date] 
    , c.[Customer number] 
    , c.[Customer name] 
    , c.[Area/state] 
    , c.country 
    , c.[Customer stop] AS [Customer Block] 
    , f.[Customer order stop] AS [Co Stop] 
    , f.[First delivery date Header] 
    , f.[Last delivery date Header] 
    , c.[User-defined field 6 - customer] 
    , c.[Customer group name] 
    , f.[Contact Method] 
    , f.[Customer order number] 
    , f.[Price Level] 
    , f.[Item number] 
    , i.[Product group description] AS [Item name] 
    , f.[Ordered quantity - basic U/M] AS [Quantity Ordered] 
    , f.[Ordered quantity - basic U/M] * f.[Net price] AS [Order Line Total ] 

    -- I've also added schema prefix. See below * 
FROM 
    dbo.AA_FactSalesOrderDetails AS f 
-- I've removed the join to Dim_SalesOrganisation as per above 
    LEFT OUTER JOIN dbo.Dim_Customers AS c 
     ON f.c_dKey = c.Dim_Customers_dKey 
    LEFT OUTER JOIN dbo.Dim_Items AS i 
     ON f.[Item number] = i.[Item number] 
    -- I've removed the join to Dim_CustomerOrderTypes since it is never used 
WHERE 
    -- in case [Order Date] is DATETIME and includes time information. See below ** 
    f.[Order Date] >= @StartDate 
    AND f.[Order Date] < DATEADD(DAY, 1, @EndDate) 
    -- still need to restrict it to the stated salesperson 
    AND f.SalesPerson = @SalesPersonCode; 

*http://sqlblog.com/blogs/aaron_bertrand/archive/2009/10/11/bad-habits-to-kick-avoiding-the-schema-prefix.aspx

**http://sqlblog.com/blogs/aaron_bertrand/archive/2009/10/16/bad-habits-to-kick-mishandling-date-range-queries.aspx

Answer 3

雖然@hatchet是正確的在避免使用WHERE條款的功能，我想這不是在這種情況下的問題，因爲它用於標量值（只能確定實際的查詢計劃）。

當然，您可以刪除對錶Dim_CustomerOrderTypes的引用，即不過濾或返回任何數據。我相信這個查詢應該提高性能使用以下索引：

-- to seek on [Salesperson] and scan on [Order Date] 
CREATE CLUSTERED INDEX IDXC ON AA_FactSalesOrderDetails([Salesperson], [Order Date]); 

-- to seek on key 
CREATE CLUSTERED INDEX IDXC ON Dim_Customers([Dim_Customers_dKey]); 

-- to seek only this index instead of reading from table 
CREATE INDEX IDX0 ON Dim_SalesOrganisation([Salesperson], [Salesperson name]); 

-- to seek only this index instead of reading from table 
CREATE INDEX IDX0 ON Dim_Items ([Item number], [Product group description]) 

我希望這些建議可以幫助你。