Windows apps
Collapse the table of content
Expand the table of content
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

ParallelEnumerable.Join<TOuter, TInner, TKey, TResult> Method (ParallelQuery<TOuter>, IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, TInner, TResult>)

.NET Framework (current version)

The .NET API Reference documentation has a new home. Visit the .NET API Browser on to see the new experience.

Note: This API is now obsolete.

This Join overload should never be called. This method is marked as obsolete and always throws NotSupportedException when invoked.

Namespace:   System.Linq
Assembly:  System.Core (in System.Core.dll)

[ObsoleteAttribute("The second data source of a binary operator must be of type System.Linq.ParallelQuery<T> rather than System.Collections.Generic.IEnumerable<T>. To fix this problem, use the AsParallel() extension method to convert the right data source to System.Linq.ParallelQuery<T>.")]
public static ParallelQuery<TResult> Join<TOuter, TInner, TKey, TResult>(
	this ParallelQuery<TOuter> outer,
	IEnumerable<TInner> inner,
	Func<TOuter, TKey> outerKeySelector,
	Func<TInner, TKey> innerKeySelector,
	Func<TOuter, TInner, TResult> resultSelector


Type: System.Linq.ParallelQuery<TOuter>

This parameter is not used.

Type: System.Collections.Generic.IEnumerable<TInner>

This parameter is not used.

Type: System.Func<TOuter, TKey>

This parameter is not used.

Type: System.Func<TInner, TKey>

This parameter is not used.

Type: System.Func<TOuter, TInner, TResult>

This parameter is not used.

Return Value

Type: System.Linq.ParallelQuery<TResult>

This overload always throws a NotSupportedException.

Type Parameters


This type parameter is not used.


This type parameter is not used.


This type parameter is not used.


This type parameter is not used.

Exception Condition

The query was canceled with the token passed in through WithCancellation.


source or action is a null reference (Nothing in Visual Basic).


One or more exceptions occurred during the evaluation of the query.

This overload exists to disallow usage Join with a left data source of type ParallelQuery<TSource> and a right data source of type IEnumerable<T>. Otherwise, the Join operator would appear to be binding to the parallel implementation, but would in reality bind to the sequential implementation.

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1
Return to top
© 2018 Microsoft