ASP.NET 4 includes a feature called SQL cache invalidation. Before ASP.NET 2.0, cachingthe results that came from SQL Server and updating the cache based on a time interval was possible — for example, every 15 seconds or so.

This meant that the end user might see stale data if the result set changedsometime during that 15-second period.In some cases, this time interval result set is unacceptable. In an ideal situation, the result set stored in thecache is destroyed if any underlying change occurs in the source from which the result set is retrieved — inthis case, SQL Server.

With ASP.NET 4, you can make this happen with the use of SQL cache invalidation.This means that when the result set from SQL Server changes, the output cache is triggered to change, andthe end user always sees the latest result set. The data presented is never stale.