Spotlight on 2010: Large List Resource Throttling

By Ryan Keller, SharePoint911

On the performance front in SharePoint 2010, several new features have been introduced to keep your server farm running at its optimal level. One of these features is Large List Resource Throttling. But what exactly is it, what does it do, and why would you need it?

List size capacity has grown dramatically in SharePoint 2010, with projections that they will be able to accommodate up to 50 million items—well over the limits present in SharePoint 2007. A downside to the ability to handle this many items is the fact that it takes a lot of processing power and time to render a huge number of items at once.

In order to avoid taxing the servers too heavily, administrators have the ability to configure Large List Resource Throttling on a per-Web application basis throughout the farm. The throttling settings apply to all lists in all site collections contained in that Web application.

To set the throttling properties in Central Administration, click on Application Management and select Manage Web Applications. Select the Web application you want to configure, and in the Ribbon, click the dropdown under General Settings and select Resource Throttling to open the Resource Throttling window.

List throttling sets a limit to the number of items that can be displayed at a time in a list, preventing the server from becoming overloaded while rendering a particularly large number of items. Any user trying to access a view of a list that exceeds the threshold will be presented with a message explaining that the request could not be processed. The user has the option to create a new view of the list that meets the threshold requirements.

By default, the item threshold per view is 5,000 items for users and 20,000 items for administrators. These limits can easily be adjusted in Central Administration based on the requirements of the organization. Server hardware and network performance can also be a factor in determining the limits on list items.

In addition, administrators can provide a window of time during which the list-throttling feature is disabled, allowing users full access to large views of the lists on a site. Because rendering large lists can heavily tax the server's resources, it is best to enable the window for large queries during off-peak hours.

As a final note, one thing administrators should be aware of is the behavior of large lists after an upgrade. When upgrading from SharePoint 2007 to SharePoint 2010, any list with a default view that exceeds the threshold set in SharePoint 2010 will not be immediately available until a new default view is created.

Large List throttling is just one of the many useful performance features to be found in SharePoint 2010. Try out the SharePoint 2010 Beta 2 and start looking at the new performance management features to determine what will work for your organization. When it's time to upgrade, you will have a better idea of what performance management features you will want to employ in your environment.