Virtualization loads all items for each group

[Markus]

I bound a RadGridView to a VirtualQueryableCollectionView backed by SQL using System.Data.Linq.ITable.

At first Virtualization works nicely as I see that the LoadSize is submitted to the SQL provider (tracing SQL queries).
Once I add grouping (dragging a column into the grouping panel) all rows for each group are loaded. 

        <telerik:RadGridView x:Name="Table" ItemsSource="{Binding Data}" AutoGenerateColumns="False" IsReadOnly="True" 
                             Height="500" Width="500"
                             GroupRenderMode="Flat"
                             CanUserInsertRows="False" CanUserDeleteRows="False"
                             EnableRowVirtualization="True" EnableColumnVirtualization="True"
                             ScrollMode="Deferred"/>

Is UI virtualization supported in a group scenario? Am I missing some settings?

[Dimitrina]

Hello,

The default grouping is the one that occurs as the user drags a column header and drops it into the GroupPanel. Then, we internally generate and execute a LINQ query appending a GroupBy clause to the source collection.

WCF RIA Services do not support true server-side grouping. They translate it to sorting instead. The grouping is done solely on the client by RadGridView and that why all the items need to be downloaded.

Regards,
Didie
Telerik