NullReferenceException when materialing object with AsNoTracking() in EF 6.3.0 and higher

[jonnybee]

This could be a tricky one and may be located in Oracle.ManagedDataAccesss.EntityFramework

I've been digging into this issue this weekend and it surfaced by a this change in commit 2483303 "Query compilation performance" #430:

    private const int MaxNodeCountForTransformations = 100000;   // from 
    private const int MaxNodeCountForTransformations = 10000;     // to 

For my app I could workaround by adding this switch to the web.config/app.config

<configuration>  
    <system.diagnostics>  
         <switches>  
                 <add name="System.Data.Entity.Core.EntityClient.IgnoreOptimizationLimit" value="1"/>  
         </switches>  
    </system.diagnostics>  
 </configuration> 

When you have large queries that hit this threshold in the PlanOptimizer (+370 columns and a number of tables, my query has nodecount=16885) the ObjectStateManager.AddEntityToCollectionOrReference may get a NullEntityWrapper in wrappedTarget parameter and this blows up in a NullReferenceException in GetOtherEndOfRelationship:

    internal RelatedEnd GetOtherEndOfRelationship(IEntityWrapper wrappedEntity)
    {
        DebugCheck.NotNull(wrappedEntity);
        EnsureRelationshipNavigationAccessorsInitialized();
        return wrappedEntity.RelationshipManager.GetRelatedEnd(_navigation.Reverse, _relationshipFixer);
    }

where a NullEntityWrapper returns

    public RelationshipManager RelationshipManager
    {
        get
        {
            Debug.Fail("Cannot access RelationshipManager from null wrapper.");
            return null;
        }
    }

When materializing objects in Shaper.MaterializeRow() the Coordinator for one (and only one) of the child collections in the Include(...) returns a NullEntityWrapper.

We have only seen this Exception when running EF Queries with AsNoTracking() against Oracle DB in our app, running the same queries without AsNoTracking() does not throw exception. And against SqlServer both with and without AsNoTracking() is working fine.

So is this most likely a bug in the Oracle.ManagedDataAccess.EntityFramework provider or a bug in EF 6 itself?

@efeblesp for notification.

Originally posted by @jonnybee in #1408 (comment)

[jonnybee]

Sorry, closing this issue. I cannot reproduce this exception now with latest versions of EF 6 and Oracle provider.

[efeblesp]

Hi @jonnybee , what version of EF and Oracle you used that worked? Did you try with the same query that previously failed with older version of EF?

[jonnybee]

I used the same Query that previously failed with EF 6.4.4, Oracle.ManagedDataAccess v 19.10.0 and Oracle.ManagedDataAccess.EntityFramework v 19.7.0 and it was working fine now.