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ParallelEnumerable.Join(Of TOuter, TInner, TKey, TResult) Method (ParallelQuery(Of TOuter), ParallelQuery(Of TInner), Func(Of TOuter, TKey), Func(Of TInner, TKey), Func(Of TOuter, TInner, TResult), IEqualityComparer(Of TKey))

Correlates in parallel the elements of two sequences based on matching keys. A specified IEqualityComparer(Of T) is used to compare keys.

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

<ExtensionAttribute> _
Public Shared Function Join(Of TOuter, TInner, TKey, TResult) ( _
	outer As ParallelQuery(Of TOuter), _
	inner As ParallelQuery(Of TInner), _
	outerKeySelector As Func(Of TOuter, TKey), _
	innerKeySelector As Func(Of TInner, TKey), _
	resultSelector As Func(Of TOuter, TInner, TResult), _
	comparer As IEqualityComparer(Of TKey) _
) As ParallelQuery(Of TResult)

Type Parameters


The type of the elements of the second sequence.


The type of the elements of the first sequence.


The type of the keys returned by the key selector functions.


The type of the result elements.


Type: System.Linq.ParallelQuery(Of TOuter)

The first sequence to join.

Type: System.Linq.ParallelQuery(Of TInner)

The sequence to join to the first sequence.

Type: System.Func(Of TOuter, TKey)

A function to extract the join key from each element of the first sequence.

Type: System.Func(Of TInner, TKey)

A function to extract the join key from each element of the second sequence.

Type: System.Func(Of TOuter, TInner, TResult)

A function to create a result element from two matching elements.

Type: System.Collections.Generic.IEqualityComparer(Of TKey)

An IEqualityComparer(Of T) to hash and compare keys.

Return Value

Type: System.Linq.ParallelQuery(Of TResult)
A sequence that has elements of type TResult that are obtained by performing an inner join on two sequences.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type ParallelQuery(Of TOuter). When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).


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.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1
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