关于索引视图的困惑

Question

我有以下索引视图：

ALTER View [CIC].[vwCoaterC473Heat] WITH SCHEMABINDING
AS

Select
    id as ID,
    DATEADD(ms, -DATEPART(ms, read_time), read_time) as ReadTime,
    equipment_id as EquipmentID,
    ...
    ...
From dbo.td_coater_c473_heat
Where read_time >= Convert(dateTime,'1/1/2012',120)

CREATE UNIQUE CLUSTERED INDEX [IX_vwCoaterC473Heat_ReadTime_EquipmentID_ID] 
ON [CIC].[vwCoaterC473Heat] 
(
    [ReadTime] ASC,
    [EquipmentID] ASC,
    [ID] ASC
)
GO

我有以下查询引用索引视图：

Select
   r.Coater,
   r.ReadTime,
   C473_left_A_actual_Temp,
   C473_right_A_actual_Temp,
   C473_left_B_actual_Temp,
   C473_right_B_actual_Temp,
   HD02A_Actual_Voltage,
   HD02A_Actual_Current,
   HD02B_Actual_Voltage,    
   HD02B_Actual_Current
From Cic.RandyTemp r
   Inner Join Cic.vwCoaterC473Heat a 
   On a.EquipmentId = r.Coater And a.ReadTime = r.ReadTime  

从中生成的查询计划如下所示：

我很好奇为什么SQL Server绕过索引视图中的持久数据，并查询视图所依据的基础表。

Answer 1

您使用的是SQL Server标准版吗？如果是这样，您需要使用WITH (NOEXPAND)提示。请尝试此版本，看看是否使用了索引视图。可能只是优化器决定访问基表中的索引更有效。

SELECT
   r.Coater,
   r.ReadTime,
   C473_left_A_actual_Temp, -- why no alias prefixes from here down?
   C473_right_A_actual_Temp,
   C473_left_B_actual_Temp,
   C473_right_B_actual_Temp,
   HD02A_Actual_Voltage,
   HD02A_Actual_Current,
   HD02B_Actual_Voltage,    
   HD02B_Actual_Current
FROM Cic.RandyTemp AS r
   INNER JOIN Cic.vwCoaterC473Heat AS a WITH (NOEXPAND)
   ON a.EquipmentId = r.Coater 
   AND a.ReadTime = r.ReadTime;