SqlDependency vs SqlCacheDependency

Question

What are the key differences between these and when should they be used? My initial understanding was that SqlCacheDependency used polling but I\'ve read it doesn\'t have too fo

Answer 1

Query Notification is the underlying technology. SqlNotificationRequest is the ADO.Net client support. SqlDependency is the ADO.Net infrastructure to automate the deployment of temporary objects needed by SqlNotificationRequest. SqlCacheDependency uses SqlDependency to integrate it with the ASP caching infrastructure. See more at The Mysterious Notification.

Note on them work with LINQ. See LinqToCache for a project that leverages Query Notifications with LINQ queries, and also explains why the vast majority of LINQ queries cannot use Query Notifications.