CREATE WORKLOAD GROUP (Transact-SQL)

  • Article

Creates a Resource Governor workload group and associates the workload group with a Resource Governor resource pool. Resource Governor is not available in every edition of Microsoft SQL Server. For a list of features that are supported by the editions of SQL Server, see Features Supported by the Editions of SQL Server 2012.

Topic link icon Transact-SQL Syntax Conventions.

Syntax

CREATE WORKLOAD GROUP group_name
[ 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" } ]
[ ; ]

Arguments

  • group_name
    Is the user-defined name for the workload group. group_name is alphanumeric, can be up to 128 characters, must be unique within an instance of SQL Server, and must comply with the rules for identifiers.

  • IMPORTANCE = { LOW | MEDIUM | HIGH }
    Specifies the relative importance of a request in the workload group. Importance is one of the following, with MEDIUM being the default:

    • LOW

    • MEDIUM

    • HIGH

    Note

    Internally each importance setting is stored as a number that is used for calculations.

    IMPORTANCE is local to the resource pool; workload groups of different importance inside the same resource pool affect each other, but do not affect workload groups in another resource pool.

  • REQUEST_MAX_MEMORY_GRANT_PERCENT =value
    Specifies the maximum amount of memory that a single request can take from the pool. This percentage is relative to the resource pool size specified by MAX_MEMORY_PERCENT.

    Note

    The amount specified only refers to query execution grant memory.

    value must be 0 or a positive integer. The allowed range for value is from 0 through 100. The default setting for value is 25.

    Note the following:

    • Setting value to 0 prevents queries with SORT and HASH JOIN operations in user-defined workload groups from running.

    • We do not recommend setting value greater than 70 because the server may be unable to set aside enough free memory if other concurrent queries are running. This may eventually lead to query time-out error 8645.

    Note

    If the query memory requirements exceed the limit that is specified by this parameter, the server does the following:

    For user-defined workload groups, the server tries to reduce the query degree of parallelism until the memory requirement falls under the limit, or until the degree of parallelism equals 1. If the query memory requirement is still greater than the limit, error 8657 occurs.

    For internal and default workload groups, the server permits the query to obtain the required memory.

    Be aware that both cases are subject to time-out error 8645 if the server has insufficient physical memory.

  • REQUEST_MAX_CPU_TIME_SEC =value
    Specifies the maximum amount of CPU time, in seconds, that a request can use. value must be 0 or a positive integer. The default setting for value is 0, which means unlimited.

    Note

    Resource Governor will not prevent a request from continuing if the maximum time is exceeded. However, an event will be generated. For more information, see CPU Threshold Exceeded Event Class.

  • REQUEST_MEMORY_GRANT_TIMEOUT_SEC =value
    Specifies the maximum time, in seconds, that a query can wait for a memory grant (work buffer memory) to become available.

    Note

    A query does not always fail when memory grant time-out is reached. A query will only fail if there are too many concurrent queries running. Otherwise, the query may only get the minimum memory grant, resulting in reduced query performance.

    value must be 0 or a positive integer. The default setting for value, 0, uses an internal calculation based on query cost to determine the maximum time.

  • MAX_DOP =value
    Specifies the maximum degree of parallelism (DOP) for parallel requests. value must be 0 or a positive integer. The allowed range for value is from 0 through 64. The default setting for value, 0, uses the global setting. MAX_DOP is handled as follows:

    • MAX_DOP as a query hint is effective as long as it does not exceed workload group MAX_DOP. Beginning with SQL Server 2008, if the MAXDOP query hint value exceeds the value that is configured by using the Resource Governor, the Database Engine uses the Resource Governor MAXDOP value.

    • MAX_DOP as a query hint always overrides sp_configure 'max degree of parallelism'.

    • Workload group MAX_DOP overrides sp_configure 'max degree of parallelism'.

    • If the query is marked as serial at compile time, it cannot be changed back to parallel at run time regardless of the workload group or sp_configure setting.

    • After DOP is configured, it can only be lowered on grant memory pressure. Workload group reconfiguration is not visible while waiting in the grant memory queue.

  • GROUP_MAX_REQUESTS =value
    Specifies the maximum number of simultaneous requests that are allowed to execute in the workload group. value must be a 0 or a positive integer. The default setting for value, 0, allows unlimited requests. When the maximum concurrent requests are reached, a user in that group can log in, but is placed in a wait state until concurrent requests are dropped below the value specified.

  • USING { pool_name | "default" }
    Associates the workload group with the user-defined resource pool identified by pool_name. This in effect puts the workload group in the resource pool. If pool_name is not provided, or if the USING argument is not used, the workload group is put in the predefined Resource Governor default pool.

    "default" is a reserved word and when used with USING, must be enclosed by quotation marks ("") or brackets ([]).

    Note

    Predefined workload groups and resource pools all use lower case 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.

Remarks

REQUEST_MEMORY_GRANT_PERCENT: Index creation is allowed to use more workspace memory than what is initially granted for improved performance. This special handling is supported by Resource Governor in SQL Server 2012. However, the initial grant and any additional memory grant are limited by resource pool and workload group settings.

Index Creation on a Partitioned Table

The memory consumed by index creation on non-aligned partitioned table is proportional to the number of partitions involved. If the total required memory exceeds the per-query limit (REQUEST_MAX_MEMORY_GRANT_PERCENT) imposed by the Resource Governor workload group setting, this index creation may fail to execute. Because the "default" workload group allows a query to exceed the per-query limit with the minimum required memory, the user may be able to run the same index creation in "default" workload group, if the "default" resource pool has enough total memory configured to run such query.

Permissions

Requires CONTROL SERVER permission.

Examples

The following example shows how to create a workload group named newReports. It uses the Resource Governor default settings and is in the Resource Governor default pool. The example specifies the default pool, but this is not required.

CREATE WORKLOAD GROUP newReports
    USING "default" ;
GO

See Also

Reference

ALTER WORKLOAD GROUP (Transact-SQL)

DROP WORKLOAD GROUP (Transact-SQL)

CREATE RESOURCE POOL (Transact-SQL)

ALTER RESOURCE POOL (Transact-SQL)

DROP RESOURCE POOL (Transact-SQL)

ALTER RESOURCE GOVERNOR (Transact-SQL)