How can you use SQL Server Resource Governor to manage performance?

The Resource Governor is composed of three main components Resource Pools – Resource pools represents the physical resources of an instance of the Database Engine. The Internal Pool is used by SQL Server itself. All user activity takes place in the Default Pool. Workload Groups – Workload groups represent the jobs running on the system. Each workload group describes application requests that are similar. Like the Resource Governor, by default there are two workload groups: the Internal workload group and the Default workload group. To limit the resources used by one or more applications you would create Classifier Function – The Classifier Function evaluates incoming session requests and routes them to the appropriate workload group

Resource pools in SQL Server help manage workloads, providing isolation and control. They ensure fair resource distribution, prioritize critical tasks, and maintain consistent performance. Useful for multitenant environments, maintenance tasks, and resource-intensive operations, resource pools are a vital tool for achieving predictability and efficiency in SQL Server. By defining and configuring these pools, administrators can maintain a balanced, high-performing database environment.

Workload groups in SQL Server streamline resource allocation, enabling efficient management of concurrent workloads. They classify and prioritize sessions, ensuring critical tasks get the resources they need. Workload groups prove valuable in multitenant systems, preventing resource monopolization, and enhancing user experience. By properly configuring workload groups, database administrators can achieve better resource distribution, maintaining optimal performance and stability.

Classifier functions in SQL Server enable intelligent workload classification. They help route connections to the right workload groups, allowing resource prioritization. Classifier functions prove invaluable in multi-application environments, ensuring fair resource distribution. By utilizing these functions effectively, administrators maintain control, allocate resources optimally, and ensure predictable performance, resulting in a well-balanced, high-performing SQL Server ecosystem.

Classifier functions are called every time there’s a connection. As a result, they must be as efficient as possible or performance of the entire SQL Server instance will degrade. Also note a classifier function cannot be altered while it’s in use - either have an alternate to switch to or tell Resource Governor not to use any classifier while you make updates (this effectively disables Resource Governor for new connections).

Before enabling Resource Governor in production, be sure to test! Once enabled, monitor closely because a poor configuration could cause more problems than you are trying to solve. The DMVs sys.dm_resource_governor_resource_pools and sys.dm_resource_governor_workload_groups are very helpful for monitoring effectiveness.