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ALTER RESOURCE POOL (Transact-SQL)

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Applies to: SQL Server Azure SQL Managed Instance

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

Transact-SQL syntax conventions

Syntax

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]

Arguments

{ 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.

Note

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 (11.x) and later.

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.

Note

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 (11.x) and later.

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 (12.x) and later.

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 (12.x) and later.

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.

Remarks

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.

Caution

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.

Permissions

Requires CONTROL SERVER permission.

Examples

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 (11.x) and later.

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

See Also

Resource Governor
CREATE RESOURCE POOL (Transact-SQL)
DROP RESOURCE POOL (Transact-SQL)
CREATE WORKLOAD GROUP (Transact-SQL)
ALTER WORKLOAD GROUP (Transact-SQL)
DROP WORKLOAD GROUP (Transact-SQL)
ALTER RESOURCE GOVERNOR (Transact-SQL)