SQL Server 2008 R2 : Managing Workloads with the Resource Governor - Modifying Your Resource Governor Configuration

Alternatively, you can modify the resource pool using the ALTER RESOURCE POOL command. With this command, you can modify the minimum and maximum CPU and memory percentages for a resource pool. The syntax is as follows:

ALTER RESOURCE POOL { pool_name | "default" }
[WITH
          ( [ MIN_CPU_PERCENT = value ]
     [ [ , ] MAX_CPU_PERCENT = value ]
     [ [ , ] MIN_MEMORY_PERCENT = value ]
     [ [ , ] MAX_MEMORY_PERCENT = value ] )
]

You can modify workload group settings using the ALTER WORKLOAD GROUP command. You can change the workload group settings as well as move the workload group to another resource pool. The syntax is as follows:

ALTER WORKLOAD GROUP { group_name | "default" }
[ WITH
    ([ IMPORTANCE = { LOW | MEDIUM | HIGH } ]
           [ [ , ] REQUEST_MAX_MEMORY_GRANT_PERCENT = value ]
           [ [ , ] REQUEST_MAX_CPU_TIME_SEC = value ]
           [ [ , ] REQUEST_MEMORY_GRANT_TIMEOUT_SEC = value ]
           [ [ , ] MAX_DOP = value ]
           [ [ , ] GROUP_MAX_REQUESTS = value ] )
]
[ USING { pool_name | "default" } ]

The following example moves the ReportWG1 workload group from the ReportPool resource pool to the default resource pool:

ALTER WORKLOAD GROUP ReportWG1
USING [default];
GO
ALTER RESOURCE GOVERNOR RECONFIGURE
GO

You can also move a workload group to another resource pool in SSMS using the Resource Governor Properties page. Click the Resource Pool name in the Resource Pools grid; then right-click on Workload Group in the Workload Groups grid and select Move To (see Figure 1). This brings up the Move Workload Group dialog, which lists the available resource pools the workload group can be moved to. Select the desired resource pool and click OK.

Figure 1. Moving a workload group in SSMS.

Why move a workload group to a different resource pool? You might decide that a workload group should be in a resource pool that has different configuration settings, or you might want to move workload groups out of a resource pool so that you can drop the resource pool.

Deleting Workload Groups

You can delete a workload group or resource pool by using SQL Server Management Studio or T-SQL. To drop a workload group in SSMS, follow these steps:

To drop a workload group using T-SQL, use the DROP WORKLOAD GROUP command:

DROP WORKLOAD GROUP OLTPWG1
ALTER RESOURCE GOVERNOR RECONFIGURE
go

You cannot drop a workload group if there are any active sessions assigned to it. If a workload group contains active sessions, deleting the workload group or moving it to a different resource pool will fail when the ALTER RESOURCE GOVERNOR RECONFIGURE statement is called to apply the change. The following options provide a way to work around this problem:

• Wait until all the sessions from the affected group have disconnected and then rerun the ALTER RESOURCE GOVERNOR RECONFIGURE statement.

• Explicitly stop sessions in the affected group by using the KILL command and then rerun the ALTER RESOURCE GOVERNOR RECONFIGURE statement.

• Restart SQL Server. When the restart process is complete, the deleted group will not be created, and a moved group will automatically use the new resource pool assignment.

Deleting Resource Pools

To drop a resource pool in SSMS, follow these steps:

To drop a workload group using T-SQL, use the DROP RESOURCE POOL command:

DROP RESOURCE POOL OLTPPOOL
ALTER RESOURCE GOVERNOR RECONFIGURE
go

You cannot drop a resource pool if any workload groups are still assigned to the resource pool. You need to drop the workload group or move it to another resource pool first.

Modifying a Classification Function

If you need to make a change to the classification function, it’s important to note that the function cannot be dropped or altered while it is marked as the classification function for the Resource Governor. Before you can modify or drop the classification function, you first need to disable Resource Governor. Alternatively, you can replace the classification function with another by running the ALTER RESOURCE GOVERNOR command and passing it a different CLASSIFIER_FUNCTION name. You can also simply disable the current classifier function by executing the following command:

ALTER RESOURCE GOVERNOR
  WITH (CLASSIFIER_FUNCTION = NULL);
ALTER RESOURCE GOVERNOR RECONFIGURE;

If you have a more complex set of rules to apply or want to be able to make changes more dynamically than having to replace the classification function each time you need to make a change, you can define your classifier function to look up the workload group names from a database table, rather than hard-coding the workload group names and matching criteria into the function. Performance should not be greatly affected when accessing the table to look up the workload group. The reason is that the table likely won’t be very large and should remain cached in the buffer pool because it’s being accessed repeatedly every time a connection is made to SQL Server.