Extra SQL calls after EF6 upgrade

Question

I've recently noticed some extra sql calls when using miniprofiler.

They only seem to occur after a build, and I think they appeared after upgrading to EF6.

Are they just checking for changes in models?

And can I safely ignore them?

SELECT 
    [GroupBy1].[A1] AS [C1]
    FROM ( SELECT 
        COUNT(1) AS [A1]
        FROM [dbo].[__MigrationHistory] AS [Extent1]
    )  AS [GroupBy1]



SELECT 
    [GroupBy1].[A1] AS [C1]
    FROM ( SELECT 
        COUNT(1) AS [A1]
        FROM [dbo].[__MigrationHistory] AS [Extent1]
        WHERE ([Extent1].[ContextKey] = @p__linq__0) AND (@p__linq__0 IS NOT NULL)
    )  AS [GroupBy1]


SELECT TOP (1) 
    [Project1].[C1] AS [C1], 
    [Project1].[MigrationId] AS [MigrationId], 
    [Project1].[Model] AS [Model]
    FROM ( SELECT 
        [Extent1].[MigrationId] AS [MigrationId], 
        [Extent1].[Model] AS [Model], 
        1 AS [C1]
        FROM [dbo].[__MigrationHistory] AS [Extent1]
        WHERE ([Extent1].[ContextKey] = @p__linq__0) AND (@p__linq__0 IS NOT NULL)
    )  AS [Project1]
    ORDER BY [Project1].[MigrationId] DESC

score 1 · Accepted Answer · edited May 23 '17 at 10:26

These DB calls refer to the new Migration HIstory Table feature included in EF6 when using Code-First:

Migrations history table is a table used by Code First Migrations to store details about migrations applied to the database. By default the name of the table in the database is __MigrationHistory and it is created when applying the first migration do the database. In Entity Framework 5 this table was a system table if the application used Microsoft Sql Server database. This has changed in Entity Framework 6 however and the migrations history table is no longer marked a system table.

If you aren't using them, these calls shouldn't cause any harm. You can always disable them or have EF create DB change scripts for you instead.

Extra SQL calls after EF6 upgrade

1 Answers1