Telerik's RadGridView + WCF Data Services + Entity Framework = Terrible performance - entity-framework

Question

We have a simple LOB application that:
pulls data from EF
serves data across the wire with WCF Data Services
renders that data on Telerik's RadGridView
This works really well in the default scenario as users are able to filter data by using the built-in Telerik filter control which presents all the options they want.
The problem happens when re-constructing the query sent from WCF Data Services when the 'Contains' operator is used:
WCF Data Services adds a bunch of "IIF" lambda expressions which,
EF then expands into T-SQL CASE statements
This takes a query that should look like:
SELECT TOP (25)
[Project1].[TaskID] AS [TaskID],
[Project1].[ProductSubmissionID] AS [ProductSubmissionID],
...
FROM ( SELECT
[Extent1].[TaskID] AS [TaskID],
[Extent1].[ProductSubmissionID] AS [ProductSubmissionID],
...
FROM [dbo].[Task] AS [Extent1]
LEFT OUTER JOIN [dbo].[OperationDataProduct] AS [Extent2] ON [Extent1].[ProductID] = [Extent2].[ProductID]
LEFT OUTER JOIN [dbo].[vProductOwnership] AS [Extent3] ON [Extent1].[ProductID] = [Extent3].[ProductID]
LEFT OUTER JOIN [dbo].[User] AS [Extent4] ON [Extent2].[ChannelManagerID] = [Extent4].[UserID]
LEFT OUTER JOIN [dbo].[User] AS [Extent5] ON [Extent2].[ProductOwnerID] = [Extent5].[UserID]
WHERE [Extent1].Type IN ('Content','Concept','Financial') AND [Extent1].MarketplaceName LIKE '%prod%'
Into one that looks like this:
SELECT TOP (25)
[Project1].[TaskID] AS [TaskID],
[Project1].[ProductSubmissionID] AS [ProductSubmissionID],
...
FROM ( SELECT
[Extent1].[TaskID] AS [TaskID],
[Extent1].[ProductSubmissionID] AS [ProductSubmissionID],
...
FROM [dbo].[Task] AS [Extent1]
LEFT OUTER JOIN [dbo].[OperationDataProduct] AS [Extent2] ON [Extent1].[ProductID] = [Extent2].[ProductID]
LEFT OUTER JOIN [dbo].[vProductOwnership] AS [Extent3] ON [Extent1].[ProductID] = [Extent3].[ProductID]
LEFT OUTER JOIN [dbo].[User] AS [Extent4] ON [Extent2].[ChannelManagerID] = [Extent4].[UserID]
LEFT OUTER JOIN [dbo].[User] AS [Extent5] ON [Extent2].[ProductOwnerID] = [Extent5].[UserID]
WHERE (CASE WHEN (CASE WHEN (((CASE WHEN (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END IS NULL) THEN CAST(NULL AS bit) WHEN (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END LIKE N'%prod%') THEN cast(1 as bit) WHEN ( NOT (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END LIKE N'%prod%')) THEN cast(0 as bit) END) = 1) AND ([Extent1].[SubmissionOrTaskType] IN (N'Content',N'Concept',N'Financial'))) THEN cast(1 as bit) WHEN ( NOT (((CASE WHEN (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END IS NULL) THEN CAST(NULL AS bit) WHEN (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END LIKE N'%prod%') THEN cast(1 as bit) WHEN ( NOT (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END LIKE N'%prod%')) THEN cast(0 as bit) END) = 1) AND ([Extent1].[SubmissionOrTaskType] IN (N'Content',N'Concept',N'Financial')))) THEN cast(0 as bit) END IS NULL) THEN cast(0 as bit) WHEN (((CASE WHEN (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END IS NULL) THEN CAST(NULL AS bit) WHEN (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END LIKE N'%prod%') THEN cast(1 as bit) WHEN ( NOT (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END LIKE N'%prod%')) THEN cast(0 as bit) END) = 1) AND ([Extent1].[SubmissionOrTaskType] IN (N'Content',N'Concept',N'Financial'))) THEN cast(1 as bit) WHEN ( NOT (((CASE WHEN (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END IS NULL) THEN CAST(NULL AS bit) WHEN (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END LIKE N'%prod%') THEN cast(1 as bit) WHEN ( NOT (CASE WHEN ([Extent1].[MarketplaceName] IS NULL) THEN CAST(NULL AS varchar(1)) ELSE LOWER([Extent1].[MarketplaceName]) END LIKE N'%prod%')) THEN cast(0 as bit) END) = 1) AND ([Extent1].[SubmissionOrTaskType] IN (N'Content',N'Concept',N'Financial')))) THEN cast(0 as bit) END) = 1
) AS [Project1]
ORDER BY [Project1].[TaskID] ASC
My question is: has anyone bumped into this problem before and is there a low cost solution?
I can see re-writing the EF QueryProvider to be a solution, but it's not exactly low cost.
TIA

Answer 1

We wound up writing a QueryProvider to fix this issue. It wound up being lower cost than originally expected, but still adds quiet a bit of unnecessary complexity. The IQToolkit has some decent examples of how to begin this.