为什么实体框架不在日期范围查询中使用日期索引？

Question

I have a table called BPIrequests with 28M rows, that I am using Entity Framework to query on a date range. This is the query it produces that times out:

SELECT 
    [Extent1].[Id] AS [Id], 
    [Extent1].[Request ID] AS [Request ID], 
    [Extent1].[Date] AS [Date], 
    [Extent1].[Lumen URL] AS [Lumen URL], 
    [Extent1].[Copyright owner ID] AS [Copyright owner ID], 
    [Extent1].[Copyright owner name] AS [Copyright owner name], 
    [Extent1].[Reporting organization ID] AS [Reporting organization ID], 
    [Extent1].[Reporting organization name] AS [Reporting organization name], 
    [Extent1].[URLs removed] AS [URLs removed], 
    [Extent1].[URLs that were not in Google's search index] AS [URLs that were not in Google's search index], 
    [Extent1].[URLs for which we took no action] AS [URLs for which we took no action], 
    [Extent1].[URLs pending review] AS [URLs pending review], 
    [Extent1].[From Abuser] AS [From Abuser]
FROM 
    [dbo].[BPIrequests] AS [Extent1]
WHERE 
    ((convert (datetime2, convert(varchar(255), [Extent1].[Date], 102) ,  102)) >= (convert (datetime2, convert(varchar(255), convert(datetime2, '2019-01-11 19:44:10.0000000', 121), 102) ,  102))) 
    AND ((convert (datetime2, convert(varchar(255), [Extent1].[Date], 102) ,  102)) <= (convert (datetime2, convert(varchar(255), convert(datetime2, '2019-01-26 19:44:10.8392197', 121), 102) ,  102)))

If I edit the query in SSMS to look like this it runs instantly:

SELECT 
    [Extent1].[Id] AS [Id], 
    [Extent1].[Request ID] AS [Request ID], 
    [Extent1].[Date] AS [Date], 
    [Extent1].[Lumen URL] AS [Lumen URL], 
    [Extent1].[Copyright owner ID] AS [Copyright owner ID], 
    [Extent1].[Copyright owner name] AS [Copyright owner name], 
    [Extent1].[Reporting organization ID] AS [Reporting organization ID], 
    [Extent1].[Reporting organization name] AS [Reporting organization name], 
    [Extent1].[URLs removed] AS [URLs removed], 
    [Extent1].[URLs that were not in Google's search index] AS [URLs that were not in Google's search index], 
    [Extent1].[URLs for which we took no action] AS [URLs for which we took no action], 
    [Extent1].[URLs pending review] AS [URLs pending review], 
    [Extent1].[From Abuser] AS [From Abuser]
FROM 
    [dbo].[BPIrequests] AS [Extent1]
WHERE 
    [Extent1].[Date] >= '2019-01-11'
    AND [Extent1].[Date] <= '2019-01-26'

here are the query plans for comparison:

How can I get Entity Framework to use the date index?

Answer 1

It look s like the date in the EF query comes from a string filed, and the sql query is converting the string to a date, this confuses the query optimizer, and the index never gets utilized.

The query you wrote in the management studio already treats the value as a date, so the index is used.

You should change your EF model class to use DateTime as the type for the 'Date' field