sys.dm_os_child_instances (Transact-SQL)
Applies to: 
SQL Server
Azure Synapse Analytics
Analytics Platform System (PDW)
Returns a row for each user instance that has been created from the parent server instance.
Important
This feature will be removed in a future version of SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature.
The information returned from sys.dm_os_child_instances can be used to determine the state of each User Instance (heart_beat) and to obtain the pipe name (instance_pipe_name) that can be used to create a connection to the User Instance using SQL Server Management Studio or SQLCmd. You can only connect to a User Instance after it has been started by an external process, such as a client application. SQL management tools cannot start a User Instance.
Note
User Instances are a feature of SQL Server 2012 Express only.
Note
To call this from Azure Synapse Analytics or Analytics Platform System (PDW), use the name sys.dm_pdw_nodes_os_child_instances. This syntax is not supported by serverless SQL pool in Azure Synapse Analytics.
| Column | Data type | Description |
|---|---|---|
| owning_principal_name | nvarchar(256) | The name of the user that this user instance was created for. |
| owning_principal_sid | nvarchar(256) | SID (Security-Identifier) of the principal who owns this user instance. This matches Windows SID. |
| owning_principal_sid_binary | varbinary(85) | Binary version of the SID for the user who owns the user Instance |
| instance_name | nvarchar(128) | The name of this user instance. |
| instance_pipe_name | nvarchar(260) | When a user instance is created, a named pipe is created for applications to connect to. This name can be used in a connect string to connect to this user instance. |
| os_process_id | Int | The process number of the Windows process for this user instance. |
| os_process_creation_date | Datetime | The date and time when this user instance process was last started. |
| heart_beat | nvarchar(5) | Current state of this user instance; either ALIVE or DEAD. |
| pdw_node_id | int | Applies to: Azure Synapse Analytics, Analytics Platform System (PDW) The identifier for the node that this distribution is on. |
Permissions
Requires VIEW SERVER STATE permission on the server.
Permissions for SQL Server 2022 and later
Requires VIEW SERVER PERFORMANCE STATE permission on the server.
Remarks
For more information about dynamic management view, see Dynamic Management Views and Functions (Transact-SQL) in SQL Server Books Online.