> ## Documentation Index
> Fetch the complete documentation index at: https://hub-docs.wundergraph.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Create a New Subgraph
> Create a new service boundary from an unassigned field and let Hub generate the federation schema automatically.
When a new field needs its own dedicated service, you do not need to write the federation SDL by hand. Hub's fission algorithm inspects the field's parent type and generates the new subgraph with the correct entity imports, key fields, and federation directives automatically.
## Walkthrough
### Find Your Unassigned Fields
Click **Unassigned** in the toolbar. The button shows a red badge with the count of unassigned fields on the current branch. The **Unassigned Fields** panel lists every unassigned field by name and type. Click the arrow next to a field to navigate to it on the canvas.
The Unassigned button only appears when the current branch has unassigned fields.
### Assign to a New Subgraph
Click the unassigned indicator on the field row to open the **Assign to subgraph** popover. Instead of selecting an existing subgraph, click **Create new subgraph** at the bottom of the list. The **Create New Subgraph** modal opens. Enter a name that reflects the domain of the new service and click **Create**.
### Review the Generated Schema
Hub creates the new subgraph immediately and places it on the canvas as a color-coded container with a connection line from the supergraph. To inspect the generated SDL, click **Schemas** in the top nav. The left sidebar lists every subgraph. Newly created subgraphs appear with a green badge. Select the new subgraph to view its SDL in the main panel. Confirm that the entity, key field, and assigned field are all present and correct.
### Evaluate the Service Boundary (Optional)
Click Optimizer in the toolbar to see how your operations execute against the updated schema. The Optimizer shows which services get called for each operation, in what order, and how complex each query is. Use it to check whether the new subgraph boundary introduces unnecessary service calls or affects the complexity of existing operations. See [Optimizer](/api-design/optimizer) for a full walkthrough.
A new subgraph with valid federation schema, generated from a single field assignment. Entity keys and dependencies are resolved and the subgraph composes with the rest of the graph. The Unassigned badge clears when every field is placed.