Introducing DMVs

SQL Server 2005 introduced a new concept in the Database Engine – the SQL Operating System (SQLOS). The SQLOS is an abstraction layer that encapsulates all the low-level resource management and monitoring tasks that the SQL Database Engine must perform while providing an application programming interface (API) for other components of the Database Engine to leverage these services. Not only does this centralization of resource management code make the SQL Database Engine more efficient, but it also provides a central location for monitoring various aspects of Database Engine performance. DMVs take advantage of this centralized architecture by providing the user with a mechanism to view this information in a way that is lightweight and accurate.

DMVs allow the user to query memory structures in SQLOS. Some DMVs show information that is only relevant for the specific point in time at which they are queried, while other DMVs show cumulative information that goes...