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sys.dm_exec_query_parallel_workers (Transact-SQL)

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Applies to: SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed Instance

Returns worker availability information per node.

Name Data type Description
node_id int NUMA node ID.
scheduler_count int Number of schedulers on this node.
max_worker_count int Maximum number of workers for parallel queries.
reserved_worker_count int Number of workers reserved by parallel queries, plus number of main workers used by all requests.
free_worker_count int Number of workers available for tasks.

Note: every incoming request consumes at least 1 worker, which is subtracted from the free worker count. It is possible that the free worker count can be a negative number on a heavily loaded server.
used_worker_count int Number of workers used by parallel queries.

Permissions

On SQL Server and SQL Managed Instance, requires VIEW SERVER STATE permission.

On SQL Database Basic, S0, and S1 service objectives, and for databases in elastic pools, the server admin account, the Microsoft Entra admin account, or membership in the ##MS_ServerStateReader## server role is required. On all other SQL Database service objectives, either the VIEW DATABASE STATE permission on the database, or membership in the ##MS_ServerStateReader## server role is required.

Permissions for SQL Server 2022 and later

Requires VIEW SERVER PERFORMANCE STATE permission on the server.

Examples

A. Viewing current parallel worker availability

SELECT * FROM sys.dm_exec_query_parallel_workers;

See Also

Dynamic Management Views and Functions (Transact-SQL)
Execution Related Dynamic Management Views and Functions (Transact-SQL)
sys.dm_os_workers (Transact-SQL)