Chapter 1. Using Dynamic Management Objects

Dynamic Management Objects (DMOs) are a set of SQL Server objects, referenced in the system (sys) schema, which provide the SQL Server DBA with a window into the activities being performed on their SQL Server instances, and the resources that these activities are consuming. In other words, these DMOs expose valuable information concerning the connections, sessions, transactions, SQL statements, and processes that are (or have been) executing against a database instance, the resultant workload generated on the server, how it is distributed, where the pressure points are, and so on. Having revealed a particular pressure point on their SQL Server, the DBA can then take appropriate steps to alleviate the problem, perhaps by tuning a query, adding an index, improving the disk subsystem, or simply "killing" a blocking session.

The term "dynamic" refers to the fact that the information reflected in these DMOs is generated dynamically from a vast range of "instrumentation" points in memory structures throughout the SQL Server engine. This data is then exposed in tabular form via these DMOs, either in views, in which case they are referred to as Dynamic Management Views (DMVs), or in table-values functions, in which case they are referred to as Dynamic Management Functions (DMFs).