Linq To Entities - Any VS First VS Exists

Question

I am using Entity Framework and I need to check if a product with name = \"xyz\" exists ...

I think I can use Any(), Exists() or First().

Which one is the b

Answer 1

One would think Any() gives better results, because it translates to an EXISTS query... but EF is awfully broken, generating this (edited):

SELECT 
CASE WHEN ( EXISTS (SELECT 
    1 AS [C1]
    FROM [MyTable] AS [Extent1]
    WHERE Condition
)) THEN cast(1 as bit) WHEN ( NOT EXISTS (SELECT 
    1 AS [C1]
    FROM [MyTable] AS [Extent2]
    WHERE Condition
)) THEN cast(0 as bit) END AS [C1]
FROM  ( SELECT 1 AS X ) AS [SingleRowTable1]

Instead of:

SELECT 
CASE WHEN ( EXISTS (SELECT 
    1 AS [C1]
    FROM [MyTable] AS [Extent1]
    WHERE Condition
)) THEN cast(1 as bit)
   ELSE cast(0 as bit) END AS [C1]
FROM  ( SELECT 1 AS X ) AS [SingleRowTable1]

...basically doubling the query cost (for simple queries; it's even worse for complex ones)

I've found using .Count(condition) > 0 is faster pretty much always (the cost is exactly the same as a properly-written EXISTS query)