DataReader ordinal-based lookups vs named lookups

Question

Microsoft (and many developers) claim that the SqlDataReader.GetOrdinal method improves the performance of retrieving values from a DataReader versus using named lookups ie.

Answer 1

I created a wrapper for SqlDataReader that stores orindals in a dictionary with the column name as the key.

It gives me ordinal performance gains while keeping the code more readable and less likely to break if someone changes the column order returned from stored procedures.

Friend Class DataReader
Implements IDisposable

Private _reader As SqlDataReader
Private _oridinals As Dictionary(Of String, Integer)
Private Shared _stringComparer As StringComparer = StringComparer.OrdinalIgnoreCase 'Case in-sensitive

Public Sub New(reader As SqlDataReader)
    Me._reader = reader
    Me.SetOrdinals()
End Sub

Private Sub SetOrdinals()
    Me._oridinals = New Dictionary(Of String, Integer)(_stringComparer)
    For i As Integer = 0 To Me._reader.FieldCount - 1
        Me._oridinals.Add(Me._reader.GetName(i), i)
    Next
End Sub

Public Function Read() As Boolean
    Return Me._reader.Read()
End Function

Public Function NextResult() As Boolean
    Dim value = Me._reader.NextResult()
    If value Then
        Me.SetOrdinals()
    End If
    Return value
End Function

Default Public ReadOnly Property Item(name As String) As Object
    Get
        Return Me._reader(Me.GetOrdinal(name))
    End Get
End Property

Public Function GetOrdinal(name As String) As Integer
    Return Me._oridinals.Item(name)
End Function

Public Function GetInteger(name As String) As Integer
    Return Me._reader.GetInt32(Me.GetOrdinal(name))
End Function

Public Function GetString(ordinal As Integer) As String
    Return Me._reader.GetString(ordinal)
End Function

Public Function GetString(name As String) As String
    Return Me._reader.GetString(Me.GetOrdinal(name))
End Function

Public Function GetDate(name As String) As Date
    Return Me._reader.GetDateTime(Me.GetOrdinal(name))
End Function

Public Function GetDateNullable(name As String) As Nullable(Of Date)
    Dim o = Me._reader.GetValue(Me.GetOrdinal(name))
    If o Is System.DBNull.Value Then
        Return Nothing
    Else
        Return CDate(o)
    End If
End Function

Public Function GetDecimal(name As String) As Decimal
    Return Me._reader.GetDecimal(Me.GetOrdinal(name))
End Function

Public Function GetBoolean(name As String) As Boolean
    Return Me._reader.GetBoolean(Me.GetOrdinal(name))
End Function

Public Function GetByteArray(name As String) As Byte()
    Return CType(Me._reader.GetValue(Me.GetOrdinal(name)), Byte())
End Function

Public Function GetBooleanFromYesNo(name As String) As Boolean
    Return Me._reader.GetString(Me.GetOrdinal(name)) = "Y"
End Function

'Disposable Code

End Class