Add<TKey>(Expression<Func<T,TKey>>,Boolean) Method

Creates a new index and adds it to the collection of indexes.

Syntax

Visual Basic
C#

'Declaration
 
Public Overloads Function Add(Of TKey)( _
   ByVal keySelector As System.Linq.Expressions.Expression(Of Func(Of T,TKey)), _
   ByVal keyIsUnque As System.Boolean _
) As Index(Of T,TKey)

public Index<T,TKey> Add<TKey>( 
   System.Linq.Expressions.Expression<Func<T,TKey>> keySelector,
   System.bool keyIsUnque
)

Parameters

keySelector: Key selector expression of the index, see IndexDefinition<T>.KeySelector.
keyIsUnque: true if a unique index must be created.

Type Parameters

TKey: The type of the index key.

Return Value

The new index added to the collection of indexes.

Remarks

A unique index occupies less memory and performs better than a non-unique index (although the difference isn't dramatic). Therefore, for unique keys, it's recommended to specify the corresponding index as unique.

But do that only if you are sure that the key is indeed unique, as it imposes a uniqueness constraint on the indexed collection. An attempt to modify the indexed collection violating the uniqueness throws an System.InvalidOperationException.

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

IndexCollection<T> Class
IndexCollection<T> Members
Overload List