sys.dm_os_hosts (Transact-SQL)

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)

Returns all the hosts currently registered in an instance of SQL Server. This view also returns the resources that are used by these hosts.

Note

To call this from Azure Synapse Analytics or Analytics Platform System (PDW), use the name sys.dm_pdw_nodes_os_hosts. This syntax is not supported by serverless SQL pool in Azure Synapse Analytics.

Column name	Data type	Description
host_address	varbinary(8)	Internal memory address of the host object.
type	nvarchar(60)	Type of hosted component. For example, SOSHOST_CLIENTID_SERVERSNI= SQL Server Native Interface SOSHOST_CLIENTID_SQLOLEDB = SQL Server Native Client OLE DB Provider SOSHOST_CLIENTID_MSDART = Microsoft Data Access Run Time
name	nvarchar(32)	Name of the host.
enqueued_tasks_count	int	Total number of tasks that this host has placed onto queues in SQL Server.
active_tasks_count	int	Number of currently running tasks that this host has placed onto queues.
completed_ios_count	int	Total number of I/Os issued and completed through this host.
completed_ios_in_bytes	bigint	Total byte count of the I/Os completed through this host.
active_ios_count	int	Total number of I/O requests related to this host that are currently waiting to complete.
default_memory_clerk_address	varbinary(8)	Memory address of the memory clerk object associated with this host. For more information, see sys.dm_os_memory_clerks (Transact-SQL).
pdw_node_id	int	Applies to: Azure Synapse Analytics, Analytics Platform System (PDW) The identifier for the node that this distribution is on.

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.

Remarks

SQL Server allows components, such as an OLE DB provider, that are not part of the SQL Server executable to allocate memory and participate in non-preemptive scheduling. These components are hosted by SQL Server, and all resources allocated by these components are tracked. Hosting allows SQL Server to better account for resources used by components external to the SQL Server executable.

Relationship Cardinalities

From	To	Relationship
sys.dm_os_hosts. default_memory_clerk_address	sys.dm_os_memory_clerks. memory_clerk_address	one to one
sys.dm_os_hosts. host_address	sys.dm_os_memory_clerks. host_address	one to one

Examples

The following example determines the total amount of memory committed by a hosted component.

Applies to: SQL Server 2012 (11.x) and later.

SELECT h.type, SUM(mc.pages_kb) AS commited_memory  
FROM sys.dm_os_memory_clerks AS mc   
INNER JOIN sys.dm_os_hosts AS h   
    ON mc.memory_clerk_address = h.default_memory_clerk_address  
GROUP BY h.type;  

See also

sys.dm_os_memory_clerks (Transact-SQL)
SQL Server Operating System Related Dynamic Management Views (Transact-SQL)