对此表，有一个最常用的查询，如何创建良好的索引以提高速度

Question

这是我表的构造

CREATE TABLE [dbo].[InterfaceMeraAdReport_CAV](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [reportID] [nvarchar](100) NOT NULL,
    [FromTime] [nvarchar](100) NOT NULL,
    [ToTime] [nvarchar](100) NOT NULL,
    [Customer] [nvarchar](100) NOT NULL,
    [Area] [nvarchar](100) NOT NULL,
    [Vendor] [nvarchar](100) NOT NULL,
    [SuccessCalls] [nvarchar](100) NOT NULL,
    [TotalCalls] [nvarchar](100) NOT NULL,
    [TotalMins] [nvarchar](100) NOT NULL,
    [ASR] [nvarchar](100) NOT NULL,
    [ACD] [nvarchar](100) NOT NULL,
    [Fee] [nvarchar](100) NOT NULL,
    [Cost] [nvarchar](100) NOT NULL,
    [Profix] [nvarchar](100) NOT NULL,
 CONSTRAINT [PK_MeraAdvReport_CA] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

两种最常用的查询是这种形式：

select  Customer,vendor,SUM(cast(SuccessCalls as int)) as successCalls,
SUM(cast(TotalCalls as int)) as TotalCalls,
SUM(cast(TotalMins as decimal(18,2))) as TotalMins,
case when  SUM(cast(TotalCalls as decimal(18,2)))  = 0  then 0.0 else (SUM(cast(SuccessCalls as decimal(18,2))) /  SUM(cast(TotalCalls as decimal(18,2)))) end as ASR,
case when  SUM(cast(SuccessCalls as decimal(18,2)))  = 0  then 0.0 else (SUM(cast(TotalMins as decimal(18,2))) /  SUM(cast(SuccessCalls as decimal(18,2)))) end as ACD,
SUM(cast(Profix as decimal(18,2))) as profix
from InterfaceMeraAdReport_CAV
where FromTime >= '20140128020000' and ToTime <= '20140128030000' 
 and Customer= '01.2136'  and Area  in ('62817','62818','62819','62859','62877','62878','62879') 
group by Customer,Vendor

二

select Customer,SUM(cast(SuccessCalls as int)) as successCalls,
SUM(cast(TotalCalls as int)) as TotalCalls,
SUM(cast(TotalMins as decimal(18,2))) as TotalMins,
case when  SUM(cast(TotalCalls as decimal(18,2)))  = 0  then 0.0 else (SUM(cast(SuccessCalls as decimal(18,2))) /  SUM(cast(TotalCalls as decimal(18,2)))) end as ASR,
case when  SUM(cast(SuccessCalls as decimal(18,2)))  = 0  then 0.0 else (SUM(cast(TotalMins as decimal(18,2))) /  SUM(cast(SuccessCalls as decimal(18,2)))) end as ACD
from InterfaceMeraAdReport_CAV
where FromTime >= @timeFrom and ToTime <= @timeTo
 and Customer= @customer  and Area in ('62817','62818','62819','62859','62877','62878','62879') 
group by Customer

该表每天增加约30万条记录，因此现在上面的查询变得越来越慢，

我想创建索引以提高速度，但是我不知道最有效的方法，有人可以告诉我哪些列将是最佳索引列

Answer 1

根据您的数据，您可能会发现FromTime > 20140128020000 ，尤其是ToTime < 20140128030000可能没有足够的选择性来保证仅在这两个列中的任何一个上创建索引。

因此，这将使您Customer和Area -同样，您将需要了解表中这些列的数据分布。

假设对Customer具有很高的选择性，并假设Customer与Area高度相关（即，Customer通常仅来自一个区域），则尝试使索引尽可能窄，例如：

CREATE INDEX IX_MyIndex ON InterfaceMeraAdReport_CAV(Customer)

如果客户与区域不相关，或者客户本身不是选择性的：

CREATE INDEX IX_MyIndex ON InterfaceMeraAdReport_CAV(Customer, Area)

或者，如果Area具有比客户更好的选择性：

CREATE INDEX IX_MyIndex ON InterfaceMeraAdReport_CAV(Area, Customer)

或者，如果事实证明该报告仅针对最新数据运行，并且有大量旧数据，则FromTime可能是有选择的：

CREATE INDEX IX_MyIndex ON InterfaceMeraAdReport_CAV(FromTime, Customer)

等等。例如，您将需要了解您的数据才能做出有关索引的决策。

由于仅获取选择中的6列，因此包含覆盖索引也很有意义。

CREATE INDEX IX_MyIndex ON InterfaceMeraAdReport_CAV(Customer, Area) 
INCLUDE (Vendor, SuccessCalls, TotalCalls, TotalMins, Profix);

或者，如果这两个查询是针对该表的唯一重要查询，那么您还应该考虑基于这些查询选择CLUSTERED索引，例如针对最少的页面读取进行优化。 Customer ， Area以及可能的FromTime可能最适合。

（显然，如果将其设为聚集索引，则不需要覆盖索引）。