sys.dm_os_child_instances (Transact-SQL)
Applies to: 
SQL Server (all supported versions) 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 Microsoft 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.
Remarks
For more information about dynamic management view, see Dynamic Management Views and Functions (Transact-SQL) in SQL Server Books Online.