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Issue with virtual scrolling for large number of records

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M. R.
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M. R. asked on 18 Jul 2012, 04:56 PM
Hello,

I have a large SQL Server table with over 600,000 records. I am testing based on your "Grid / Virtual Scrolling and Paging" example found at: http://demos.telerik.com/aspnet-ajax/grid/examples/client/virtualscrollpaging/defaultvb.aspx

I set VirtualItemCount to the total number of records in the table, i.e. VirtualItemCount="622840". See all code below.
Once I did this change, the scrolling behavior was completely messed-up. Please see attached screen shots, showing step by step what is happening.

Using Rad Controls for ASP.Net Ajax, version 2011.3.1305 for .Net framework 4.0 and Visual Studio 2010.
<%@ Page Title="Home Page" Language="vb" MasterPageFile="~/Site.Master" AutoEventWireup="false"
  CodeBehind="Default.aspx.vb" Inherits="DB2_Data._Default" %>
 
<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
  <h2>
 
    <telerik:RadScriptManager ID="RadScriptManager1" Runat="server">
    </telerik:RadScriptManager>
 
  </h2>
  <telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
        <AjaxSettings>
            <telerik:AjaxSetting AjaxControlID="RadGrid1">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="RadGrid1" LoadingPanelID="RadAjaxLoadingPanel1" />
                </UpdatedControls>
            </telerik:AjaxSetting>
        </AjaxSettings>
    </telerik:RadAjaxManager>
    <telerik:RadAjaxLoadingPanel ID="RadAjaxLoadingPanel1" runat="server" />

   <telerik:RadGrid ID="RadGrid1" Width="97%" AllowPaging="True" PageSize="14" AllowSorting="True"
      runat="server" AllowCustomPaging="true" VirtualItemCount="622840">
      <PagerStyle Mode="NumericPages" />
      <MasterTableView TableLayout="Fixed" />
      <ClientSettings>
          <Scrolling AllowScroll="True" EnableVirtualScrollPaging="True" UseStaticHeaders="True"
              SaveScrollPosition="True"></Scrolling>
      </ClientSettings>
    </telerik:RadGrid>
 
 <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ASWConnectionString %>"
        SelectCommand="SELECT * FROM [DB2_Customers]" ProviderName="System.Data.SqlClient"></asp:SqlDataSource>
 
</asp:Content>

Imports System.Data
Imports System.Data.SqlClient
Imports System.Collections.Generic
Imports Telerik.Web.UI
 
Public Class _Default
  Inherits System.Web.UI.Page
  Private Function GetDataTable(ByVal queryString As String) As DataTable
    Dim ConnString As String = ConfigurationManager.ConnectionStrings("ASWConnectionString").ConnectionString
    Dim MySqlConnection As New SqlConnection(ConnString)
    Dim MySqlDataAdapter As New SqlDataAdapter
    MySqlDataAdapter.SelectCommand = New SqlCommand(queryString, MySqlConnection)
 
    Dim myDataTable As New DataTable
    MySqlConnection.Open()
    Try
      MySqlDataAdapter.Fill(myDataTable)
    Finally
      MySqlConnection.Close()
    End Try
 
    Return myDataTable
  End Function
 
  Protected Sub RadGrid1_NeedDataSource(ByVal source As Object, ByVal e As GridNeedDataSourceEventArgs) Handles RadGrid1.NeedDataSource
    RadGrid1.DataSource = GetDataTable("SELECT * FROM db2_customers WHERE ID BETWEEN " & ((RadGrid1.CurrentPageIndex * RadGrid1.PageSize) + 1) & " AND " & ((RadGrid1.CurrentPageIndex + 1) * RadGrid1.PageSize))
  End Sub
End Class

Regards,
M.R.

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Milena
Telerik team
answered on 23 Jul 2012, 12:24 PM
Hello,

We are aware of this issue and our developers will have the care to it. However, this fix requires a detailed investigation and for now we cannot specify an exact date when it will be available.

All the best,
Milena
the Telerik team
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M. R.
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Milena
Telerik team
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