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ALTER RESOURCE POOL (Transact-SQL)

 

Updated: January 19, 2016

THIS TOPIC APPLIES TO: yesSQL Server noAzure SQL Database noAzure SQL Data Warehouse noParallel Data Warehouse

Changes an existing Resource Governor resource pool configuration in SQL Server.

Topic link icon Transact-SQL Syntax Conventions.


ALTER RESOURCE POOL { pool_name | "default" }
[WITH
    ( [ MIN_CPU_PERCENT = value ]
    [ [ , ] MAX_CPU_PERCENT = value ] 
    [ [ , ] CAP_CPU_PERCENT = value ] 
    [ [ , ] AFFINITY {SCHEDULER = AUTO | ( <scheduler_range_spec> ) | NUMANODE = ( <NUMA_node_range_spec> )}] 
    [ [ , ] MIN_MEMORY_PERCENT = value ]
    [ [ , ] MAX_MEMORY_PERCENT = value ] 
    [ [ , ] MIN_IOPS_PER_VOLUME = value ]
    [ [ , ] MAX_IOPS_PER_VOLUME = value ]
)] 
[;]

<scheduler_range_spec> ::=
{SCHED_ID | SCHED_ID TO SCHED_ID}[,…n]

<NUMA_node_range_spec> ::=
{NUMA_node_ID | NUMA_node_ID TO NUMA_node_ID}[,…n]

{ pool_name | "default" }

Is the name of an existing user-defined resource pool or the default resource pool that is created when SQL Server is installed.

"default" must be enclosed by quotation marks ("") or brackets ([]) when used with ALTER RESOURCE POOL to avoid conflict with DEFAULT, which is a system reserved word. For more information, see Database Identifiers.

System_CAPS_noteNote

Predefined workload groups and resource pools all use lowercase names, such as "default". This should be taken into account for servers that use case-sensitive collation. Servers with case-insensitive collation, such as SQL_Latin1_General_CP1_CI_AS, will treat "default" and "Default" as the same.

MIN_CPU_PERCENT = value

Specifies the guaranteed average CPU bandwidth for all requests in the resource pool when there is CPU contention. value is an integer with a default setting of 0. The allowed range for value is from 0 through 100.

MAX_CPU_PERCENT = value

Specifies the maximum average CPU bandwidth that all requests in the resource pool will receive when there is CPU contention. value is an integer with a default setting of 100. The allowed range for value is from 1 through 100.

CAP_CPU_PERCENT = value

Applies to: SQL Server 2012 through SQL Server 2016.

Specifies the target maximum CPU capacity for requests in the resource pool. value is an integer with a default setting of 100. The allowed range for value is from 1 through 100.

System_CAPS_noteNote

Due to the statistical nature of CPU governance, you may notice occasional spikes exceeding the value specified in CAP_CPU_PERCENT.

AFFINITY {SCHEDULER = AUTO | (Scheduler_range_spec) | NUMANODE = (NUMA_node_range_spec)}

Applies to: SQL Server 2012 through SQL Server 2016.

Attach the resource pool to specific schedulers. The default value is AUTO.

AFFINITY SCHEDULER = (Scheduler_range_spec) maps the resource pool to the SQL Server schedules identified by the given IDs. These IDs map to the values in the scheduler_id column in sys.dm_os_schedulers (Transact-SQL).

When you use AFFINITY NAMANODE = (NUMA_node_range_spec), the resource pool is affinitized to the SQL Server schedulers that map to the physical CPUs that correspond to the given NUMA node or range of nodes. You can use the following Transact-SQL query to discover the mapping between the physical NUMA configuration and the SQL Server scheduler IDs.

SELECT osn.memory_node_id AS [numa_node_id], sc.cpu_id, sc.scheduler_id
FROM sys.dm_os_nodes AS osn
INNER JOIN sys.dm_os_schedulers AS sc ON osn.node_id = sc.parent_node_id AND sc.scheduler_id < 1048576;

MIN_MEMORY_PERCENT = value

Specifies the minimum amount of memory reserved for this resource pool that can not be shared with other resource pools. value is an integer with a default setting of 0. The allowed range for value is from 0 through 100.

MAX_MEMORY_PERCENT = value

Specifies the total server memory that can be used by requests in this resource pool. value is an integer with a default setting of 100. The allowed range for value is from 1 through 100.

MIN_IOPS_PER_VOLUME = value

Applies to: SQL Server 2014 through SQL Server 2016.

Specifies the minimum I/O operations per second (IOPS) per disk volume to reserve for the resource pool. The allowed range for value is from 0 through 2^31-1 (2,147,483,647). Specify 0 to indicate no minimum threshold for the pool.

MAX_IOPS_PER_VOLUME = value

Applies to: SQL Server 2014 through SQL Server 2016.

Specifies the maximum I/O operations per second (IOPS) per disk volume to allow for the resource pool. The allowed range for value is from 0 through 2^31-1 (2,147,483,647). Specify 0 to set an unlimited threshold for the pool. The default is 0.

If the MAX_IOPS_PER_VOLUME for a pool is set to 0, the pool is not governed at all and can take all the IOPS in the system even if other pools have MIN_IOPS_PER_VOLUME set. For this case, we recommend that you set the MAX_IOPS_PER_VOLUME value for this pool to a high number (for example, the maximum value 2^31-1) if you want this pool to be governed for IO.

MAX_CPU_PERCENT and MAX_MEMORY_PERCENT must be greater than or equal to MIN_CPU_PERCENT and MIN_MEMORY_PERCENT, respectively.

MAX_CPU_PERCENT can use CPU capacity above the value of MAX_CPU_PERCENT if it is available. Although there may be periodic spikes above CAP_CPU_PERCENT, workloads should not exceed CAP_CPU_PERCENT for extended periods of time, even when additional CPU capacity is available.

The total CPU percentage for each affinitized component (scheduler(s) or NUMA node(s)) should not exceed 100%.

When you are executing DDL statements, we recommend that you be familiar with Resource Governor states. For more information, see Resource Governor.

When changing a plan affecting setting, the new setting will only take effect in previously cached plans after executing DBCC FREEPROCCACHE (pool_name), where pool_name is the name of a Resource Governor resource pool.

  • If you are changing AFFINITY from multiple schedulers to a single scheduler, executing DBCC FREEPROCCACHE is not required because parallel plans can run in serial mode. However, it may not be as efficient as a plan compiled as a serial plan.

  • If you are changing AFFINITY from a single scheduler to multiple schedulers, executing DBCC FREEPROCCACHE is not required. However, serial plans cannot run in parallel, so clearing the respective cache will allow new plans to potentially be compiled using parallelism.

System_CAPS_cautionCaution

Clearing cached plans from a resource pool that is associated with more than one workload group will affect all workload groups with the user-defined resource pool identified by pool_name.

Requires CONTROL SERVER permission.

The following example keeps all the default resource pool settings on the default pool except for MAX_CPU_PERCENT, which is changed to 25.

ALTER RESOURCE POOL "default"
WITH
     ( MAX_CPU_PERCENT = 25);
GO
ALTER RESOURCE GOVERNOR RECONFIGURE;
GO

In the following example, the CAP_CPU_PERCENT sets the hard cap to 80% and AFFINITY SCHEDULER is set to an individual value of 8 and a range of 12 to 16.

Applies to: SQL Server 2012 through SQL Server 2016.

ALTER RESOURCE POOL Pool25
WITH( 
     MIN_CPU_PERCENT = 5,
     MAX_CPU_PERCENT = 10,     
     CAP_CPU_PERCENT = 80,
     AFFINITY SCHEDULER = (8, 12 TO 16), 
     MIN_MEMORY_PERCENT = 5,
     MAX_MEMORY_PERCENT = 15
);

GO
ALTER RESOURCE GOVERNOR RECONFIGURE;
GO

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