Add<TKey>(Expression<Func<T,TKey>>,Boolean,Boolean,IndexingAlgorithm,CultureInfo) 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 keyIsUnique As System.Boolean, _
   ByVal onlyOnce As System.Boolean, _
   ByVal algorithm As IndexingAlgorithm, _
   ByVal locale As System.Globalization.CultureInfo _
) As IIndexScanner(Of T,TKey)

public IIndexScanner<T,TKey> Add<TKey>( 
   System.Linq.Expressions.Expression<Func<T,TKey>> keySelector,
   System.bool keyIsUnique,
   System.bool onlyOnce,
   IndexingAlgorithm algorithm,
   System.Globalization.CultureInfo locale
)

Parameters

keySelector: Key selector expression of the index, see KeySelector.
keyIsUnique: Specifies whether the key used in this index is a unique key for the indexed collection (default: false).
onlyOnce: Specifies whether it is required that the index does not exist prior to this method call (default: false). If an index with this keySelector already exists, an exception is thrown if it is true, and this method call is ignored if it is false.
algorithm: An IndexingAlgorithm used by the index. In the current version, only one algorithm is supported, RedBlackTree. Later versions may support other algorithms, such as bitmap or hash indexes.
locale: Locale information used to compare strings in the index (default: CultureInfo.CurrentCulture).

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

ScannerCollection<T> Class
ScannerCollection<T> Members
Overload List