Microsoft® SQL Server 2012 Unleashed

Using Application Locks

The SQL Server Lock Manager knows nothing about the object or the structure of the object it is locking. The Lock Manager simply checks whether two processes are trying to obtain incompatible locks on the same resource. If so, blocking occurs.

SQL Server allows you to extend the resources that can be locked beyond the ones automatically provided. You can define your own custom locking resources and let the Lock Manager control the access to those resources as it would for any resource in a database. This essentially allows you to choose to lock anything you want. These user-defined lock resources are called application locks. To define an application lock, you use the sp_getapplock stored procedure and specify a name for ...