WebApi oData generates incompatible SQL

Question

I'm receiving the error:

Parameters as arguments to a TOP sub-clause and a LIMIT sub-clause in a query, or a LimitExpression in a command tree, are not supported in versions of SQL Server earlier than SQL Server 2005.

When using WebAPI + oData when doing Take() in LinqPad or via http:

http://localhost:8080/odata/sample()?$top=10

However if I run a Take() against the DbContext directly it works fine. So I presume that the oData magic is creating some linq / sql which isn't supported in my setup.

The complications I have is that the EDMX needs to be setup to run in compatibility mode 80 (sql 2000).

And that I am using Composite Key in ASP.NET Web API OData (but I understand now that's the recommended approach from another post so probably isn't the problem).

And it's coming from a view, not a table.

And I'm using WebApi 1 (not 2).

Is there a way to override the SQL that is being generated so I can avoid the incompatible SQL?

EDIT:

After stepping through the webapi (and then entity framework code) - an enlightening experience, I have found the line that is throwing the exception:

In \entityframework\src\EntityFramework.SqlServer\SqlGen\Sql8ConformanceChecker.cs

/// <summary>
/// Walks the structure
/// </summary>
/// <exception cref="NotSupportedException">expression.Limit is DbParameterReferenceExpression</exception>
public override bool Visit(DbLimitExpression expression)
{
    Check.NotNull(expression, "expression");

    if (expression.Limit is DbParameterReferenceExpression)
    {
        throw new NotSupportedException(Strings.SqlGen_ParameterForLimitNotSupportedOnSql8);
    }

    return VisitExpression(expression.Argument);
}

But I'm still not sure why I can easily do a OrderBy().Take() against the context but the oData version is failing.

I've managed to compare the DbQueryCommandTree generated by oData vs the equivalent generated when querying the dbContext.

The oData version:

{DbQueryCommandTree
|_Parameters
| |_p__linq__0 : Edm.Int32
|_Query : Collection{Record['UserID'=Edm.Int32, 'RolledupReviewPeriodID'=Edm.Int32, 'UserEmployeeNumber'=Edm.String, 'FirstName'=Edm.String, 'LastName'=Edm.String, 'JobTitle'=Edm.String, 'CostCentre'=Edm.String, 'CostCentreNo'=Edm.String, 'Department'=Edm.String, 'Division'=Edm.String, 'Directorate'=Edm.String, 'AppraiserName'=Edm.String, 'ReviewDate'=Edm.DateTime, 'Status'=Edm.String, 'InterimRating'=Edm.Int32, 'IndicativeRating'=Edm.Int32, 'PreModerated'=Edm.Int32, 'ModeratedRating'=Edm.Int32, 'FinalRating'=Edm.Int32, 'ReviewPeriodName'=Edm.String]}
  |_Project
    |_Input : 'Limit1'
    | |_Limit
    |   |_Sort
    |   | |_Input : 'Extent1'
    |   | | |_Scan : PMM_ModelStoreContainer.vwReports_ReviewRatings
    |   | |_SortOrder
    |   |   |_Asc
    |   |   | |_Var(Extent1).RolledupReviewPeriodID
    |   |   |_Asc
    |   |     |_Var(Extent1).UserID
    |   |_@p__linq__0
    |_Projection
      |_NewInstance : Record['UserID'=Edm.Int32, 'RolledupReviewPeriodID'=Edm.Int32, 'UserEmployeeNumber'=Edm.String, 'FirstName'=Edm.String, 'LastName'=Edm.String, 'JobTitle'=Edm.String, 'CostCentre'=Edm.String, 'CostCentreNo'=Edm.String, 'Department'=Edm.String, 'Division'=Edm.String, 'Directorate'=Edm.String, 'AppraiserName'=Edm.String, 'ReviewDate'=Edm.DateTime, 'Status'=Edm.String, 'InterimRating'=Edm.Int32, 'IndicativeRating'=Edm.Int32, 'PreModerated'=Edm.Int32, 'ModeratedRating'=Edm.Int32, 'FinalRating'=Edm.Int32, 'ReviewPeriodName'=Edm.String]
        |_Column : 'UserID'
        | |_Var(Limit1).UserID
        |_Column : 'RolledupReviewPeriodID'
        | |_Var(Limit1).RolledupReviewPeriodID
        |_Column : 'UserEmployeeNumber'
        | |_Var(Limit1).UserEmployeeNumber
        |_Column : 'FirstName'
        | |_Var(Limit1).FirstName
        |_Column : 'LastName'
        | |_Var(Limit1).LastName
        |_Column : 'JobTitle'
        | |_Var(Limit1).JobTitle
        |_Column : 'CostCentre'
        | |_Var(Limit1).CostCentre
        |_Column : 'CostCentreNo'
        | |_Var(Limit1).CostCentreNo
        |_Column : 'Department'
        | |_Var(Limit1).Department
        |_Column : 'Division'
        | |_Var(Limit1).Division
        |_Column : 'Directorate'
        | |_Var(Limit1).Directorate
        |_Column : 'AppraiserName'
        | |_Var(Limit1).AppraiserName
        |_Column : 'ReviewDate'
        | |_Var(Limit1).ReviewDate
        |_Column : 'Status'
        | |_Var(Limit1).Status
        |_Column : 'InterimRating'
        | |_Var(Limit1).InterimRating
        |_Column : 'IndicativeRating'
        | |_Var(Limit1).IndicativeRating
        |_Column : 'PreModerated'
        | |_Var(Limit1).PreModerated
        |_Column : 'ModeratedRating'
        | |_Var(Limit1).ModeratedRating
        |_Column : 'FinalRating'
        | |_Var(Limit1).FinalRating
        |_Column : 'ReviewPeriodName'
          |_Var(Limit1).ReviewPeriodName}

The version when hitting the dbContext directly

{DbQueryCommandTree
|_Parameters
|_Query : Collection{Record['UserID'=Edm.Int32, 'RolledupReviewPeriodID'=Edm.Int32, 'UserEmployeeNumber'=Edm.String, 'FirstName'=Edm.String, 'LastName'=Edm.String, 'JobTitle'=Edm.String, 'CostCentre'=Edm.String, 'CostCentreNo'=Edm.String, 'Department'=Edm.String, 'Division'=Edm.String, 'Directorate'=Edm.String, 'AppraiserName'=Edm.String, 'ReviewDate'=Edm.DateTime, 'Status'=Edm.String, 'InterimRating'=Edm.Int32, 'IndicativeRating'=Edm.Int32, 'PreModerated'=Edm.Int32, 'ModeratedRating'=Edm.Int32, 'FinalRating'=Edm.Int32, 'ReviewPeriodName'=Edm.String]}
  |_Project
    |_Input : 'Limit1'
    | |_Limit
    |   |_Sort
    |   | |_Input : 'Extent1'
    |   | | |_Scan : PMM_ModelStoreContainer.vwReports_ReviewRatings
    |   | |_SortOrder
    |   |   |_Asc
    |   |   | |_Var(Extent1).RolledupReviewPeriodID
    |   |   |_Asc
    |   |     |_Var(Extent1).UserID
    |   |_10
    |_Projection
      |_NewInstance : Record['UserID'=Edm.Int32, 'RolledupReviewPeriodID'=Edm.Int32, 'UserEmployeeNumber'=Edm.String, 'FirstName'=Edm.String, 'LastName'=Edm.String, 'JobTitle'=Edm.String, 'CostCentre'=Edm.String, 'CostCentreNo'=Edm.String, 'Department'=Edm.String, 'Division'=Edm.String, 'Directorate'=Edm.String, 'AppraiserName'=Edm.String, 'ReviewDate'=Edm.DateTime, 'Status'=Edm.String, 'InterimRating'=Edm.Int32, 'IndicativeRating'=Edm.Int32, 'PreModerated'=Edm.Int32, 'ModeratedRating'=Edm.Int32, 'FinalRating'=Edm.Int32, 'ReviewPeriodName'=Edm.String]
        |_Column : 'UserID'
        | |_Var(Limit1).UserID
        |_Column : 'RolledupReviewPeriodID'
        | |_Var(Limit1).RolledupReviewPeriodID
        |_Column : 'UserEmployeeNumber'
        | |_Var(Limit1).UserEmployeeNumber
        |_Column : 'FirstName'
        | |_Var(Limit1).FirstName
        |_Column : 'LastName'
        | |_Var(Limit1).LastName
        |_Column : 'JobTitle'
        | |_Var(Limit1).JobTitle
        |_Column : 'CostCentre'
        | |_Var(Limit1).CostCentre
        |_Column : 'CostCentreNo'
        | |_Var(Limit1).CostCentreNo
        |_Column : 'Department'
        | |_Var(Limit1).Department
        |_Column : 'Division'
        | |_Var(Limit1).Division
        |_Column : 'Directorate'
        | |_Var(Limit1).Directorate
        |_Column : 'AppraiserName'
        | |_Var(Limit1).AppraiserName
        |_Column : 'ReviewDate'
        | |_Var(Limit1).ReviewDate
        |_Column : 'Status'
        | |_Var(Limit1).Status
        |_Column : 'InterimRating'
        | |_Var(Limit1).InterimRating
        |_Column : 'IndicativeRating'
        | |_Var(Limit1).IndicativeRating
        |_Column : 'PreModerated'
        | |_Var(Limit1).PreModerated
        |_Column : 'ModeratedRating'
        | |_Var(Limit1).ModeratedRating
        |_Column : 'FinalRating'
        | |_Var(Limit1).FinalRating
        |_Column : 'ReviewPeriodName'
          |_Var(Limit1).ReviewPeriodName}

The big different is in the oData version it's passing in the paramaters:

|_Parameters | |_p__linq__0 : Edm.Int32

Whereas the dbcontext version the parameters are just passed in directtly i.e. "10"

Answer 1

After digging as deep as a mole in a hole (gone slightly mad).

I came across this gem:

 public static IQueryable Take(IQueryable query, int count, Type type, bool parameterize)
 {
     MethodInfo takeMethod = ExpressionHelperMethods.QueryableTakeGeneric.MakeGenericMethod(type);
     Expression takeValueExpression = parameterize ? LinqParameterContainer.Parameterize(typeof(int), count) : Expression.Constant(count);

     Expression takeQuery = Expression.Call(null, takeMethod, new[] { query.Expression, takeValueExpression });
     return query.Provider.CreateQuery(takeQuery);
 }

Inside ExpressionHelpers.cs

I wanted to know what the effect of changing paramterize was on:

Expression takeValueExpression = parameterize ? LinqParameterContainer.Parameterize(typeof(int), count) : Expression.Constant(count);

Crawling back up the stack I could see it was passed in by mixing the request and context to create ODataQuerySettings.EnableConstantParameterization

Which reading Invoking Query Options Directly I can override in the controller (excellent!)

So the fix is simply the following in the controller:

 public IQueryable<T> Get(ODataQueryOptions<T> options)
 {
     ODataQuerySettings settings = new ODataQuerySettings()
     {
         EnableConstantParameterization = false
     };

     IQueryable results = options.ApplyTo(db.T.AsQueryable(), settings);

     return results as IQueryable<T>;
 }

Answer 2

Alex, great that you already found the fix for this issue. We added this configuration setting, EnableConstantParameterization`, for improving EF and SQL query cache performance. We turn it on by default as we have seen really goodperformance improvements with this enabled. Unfortunately, as you have already noticed, it might not work with older versions of SQL server.

You can disable this setting using ODataQuerySettings.EnableConstantParameterization if you are using ODataQueryOptions. If you are using QueryableAttribute, you can disable this by setting [QueryableAttribute(EnableConstantParameterization = false)].