提高连接 14 个表的 SQL 查询的性能

Question

我正在尝试加入 14 个表，其中我需要使用左联接加入其中的几个表。 现有数据大约 7000 条记录，执行以下查询大约需要 10 秒。如果记录超过百万条，恐怕会怎样。请帮助我提高以下查询的性能。

CREATE proc [dbo].[GetTodaysActualInvoiceItemSoldHistory]                          
@fromdate datetime,        
@todate datetime        
as                          

Begin                    

select SDID.InvoiceDate as [Sold Date],Cust.custCompanyName as [Sold To] ,   
case SQBD.TransferNo  when '0' then IVM.VendorName else SQBD.TransferNo end as [Purchase From],  
SQBD.BatchSellQty as SoldQty,SQID.SellPrice,  
SDID.InvoiceNo as [Sales Invoice No],INV.PRInvoiceNo as [PO Invoice No],INV.PRInvoiceDate as [PO Invoice Date],   
SQID.ItemDesc as [Item Description],SQID.NetPrice,SDHM.DeliveryHeaderMasterName as   DeliveryHeaderName,    
SQID.ItemCode as [Item Code],           
SQBD.BatchNo,SQBD.ExpiryDate,SQID.Amount,   
SQID.Dept_ID as Dept_ID,              
Dept_Name as [Department],SQID.Catg_ID as Catg_ID,                                    
Category_Name as [Category],SQID.Brand_ID as Brand_ID,               
BrandName as BrandName, SQID.Manf_Id as Manf_Id,                             
Manf.ManfName as [Manufacturer],              
STM.TaxName, SQID.Tax_ID as Tax_ID,              
INV.VendorID as VendorID,              
SQBD.ItemID,SQM.Isdeleted,  
SDHM.DeliveryHeaderMasterID,Cust.CustomerMasterID        
 from  SD_QuotationMaster SQM                  
inner join  SD_InvoiceDetails SDID on SQM.QuoteID = SDID.QuoteID                
inner join  SD_QuoteItemDetails SQID on SDID.QuoteID = SQID.QuoteID               
inner join  SD_QuoteBatchDetails SQBD on SDID.QuoteID = SQBD.QuoteID and SQID.ItemID=SQBD.ItemID              
inner join  INV_ProductInvoice INV on SQBD.InvoiceID=INV.ProductInvoiceID              
inner jOIN  INV_VendorMaster IVM ON INV.VendorID = IVM.VendorID       
inner jOIN  Sys_TaxMaster STM ON SQID.Tax_ID = STM.Tax_ID                 
inner join Cust_CustomerMaster Cust on SQM.CustomerMasterID = Cust.CustomerMasterID    
left jOIN  INV_DeptartmentMaster Dept ON SQID.Dept_ID = Dept.Dept_ID                                       
left jOIN  INV_BrandMaster BRD ON SQID.Brand_ID = BRD.Brand_ID                                       
left jOIN  INV_ManufacturerMaster  Manf ON SQID.Manf_Id = Manf.Manf_Id                
left join INV_CategoryMaster CAT ON SQID.Catg_ID = CAT.Catg_ID                                                              
left join SLRB_DeliveryCustomerMaster SDCM on SQM.CustomerMasterID=SDCM.CustomerMasterID and SQM.DeliveryHeaderMasterID=SDCM.DeliveryHeaderMasterID                                       
left join SLRB_DeliveryHeaderMaster SDHM on SDCM.DeliveryHeaderMasterID=SDHM.DeliveryHeaderMasterID                               
where (SQM.IsDeleted=0)  and SQBD.BatchSellQty > 0          

and SDID.InvoiceDate between @fromdate and @todate                
order by ItemDesc                     

End 

只有下表包含更多的数据，而其他表的记录少于 20

InvoiceDetails, QuoteMaster, QuoteItemDetails, QuoteBatchDetails ProductInvoice

下面是执行计划的链接

http://jmp.sh/CSZc2x2

谢谢。

Answer 1

让我们从一个明显的错误开始：

(isnull(SQBD.BatchSellQty,0) > 0)

那个是不可索引的，所以它不应该发生。说真的，在大多数情况下，BatchSellQty 不应该是未知的（可为空的），或者您最好正确处理 null。该字段应该被索引，我不确定我是否希望使用 isNull - 可能有大量批次。另请注意，过滤索引（条件 >0）可能在这里起作用。

其次，检查您是否拥有所有正确的索引以及执行计划是否合理。

因此，您必须使用大量数据进行测试。索引统计数据可能会有所不同。检查时间花在哪里 - 它可能是 tempdb，在这种情况下，您确实需要良好的 tempdb IO 速度....并且它与输入端无关。

Answer 2

您可以尝试使用query hints 来帮助SQL Server 优化器构建最佳查询执行计划。例如，您可以使用FORCE ORDER 语句强制连接表的顺序。如果您按照在每个步骤中以最小结果大小连接的顺序对表进行排序，则查询将执行得更快（可能需要尝试）。示例：

We need to A join B join C
If A join B = 2000 records x 1000 records = ~400 records (we suspect this result)
And A join C = 2000 records x 10 records = ~3 records (and this)
And B join C = 1000 records x 10 records = 10 000 records (and this)

在这种情况下，最佳顺序将是

A join C join B = ~3 records x 1000 records = ~3000 records