> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

# Modify Collections in Your Compass Entity-Relationship Diagram

MongoDB Compass Readonly Edition will be deprecated in a future release. To replicate the read-only behavior in a standard Compass edition, assign users [`read`](https://www.mongodb.com/docs/manual/reference/built-in-roles.md#mongodb-authrole-read) access at the database level and enable the [readOnly](https://www.mongodb.com/docs/compass/settings/read-only.md#std-label-compass-read-only) option in Compass.

You can modify your existing entity-relationship diagram in Compass to plan changes to your data model *without* affecting your actual data.

## About this Task

In the Data Modeling tab, you can:

- Add or remove collections

- Rename collections

**Note:**

Any changes you make to your entity-relationship diagram won't affect your actual database.

## Before You Begin

You must have an existing entity-relationship diagram in Compass to modify the fields. To create a new diagram, see [Generate an Entity-Relationship Diagram in Compass.](https://www.mongodb.com/docs/compass/data-modeling/generate-diagram.md#std-label-compass-create-data-model-diagram)

## Steps

### Add a New Collection

To add a new collection to your entity-relationship diagram:

1. Open the Data Modeling tab

   In the left sidebar, click  Data Modeling.

2. Open your entity-relationship diagram

   From the  Data Modeling tab, open your diagram.

3. Add a new collection

   To add a new collection, click the  icon in the upper-left corner of the diagram canvas. Clicking this icon opens a drop-down menu with two options:

   - Add a new collection

   - Select from database

   ![Add collection icon in the Data Modeling tab](/images/compass/dm-add-collection.png)

   If you click Select from database, a dialog box opens that allows you to select existing collections from your database that aren't included in your diagram.

   **Note:**

   If you imported your diagram or you aren't connected to the database used to generate your diagram, Compass prompts you to select a database connection.

### Rename a Collection

To rename a collection in your entity-relationship diagram:

1. Open the Data Modeling tab

   In the left sidebar, click  Data Modeling.

2. Open your entity-relationship diagram

   From the  Data Modeling tab, open your diagram.

3. Open the Collection Properties side panel

   Click one of your collections in the diagram. The collection side panel opens on the right side of the screen.

### Remove a Collection

To delete a collection from your diagram:

1. Open the Data Modeling tab

   In the left sidebar, click  Data Modeling.

2. Open your entity-relationship diagram

   From the  Data Modeling tab, open your diagram.

3. Open the Collection Properties side panel

   Click one of your collections in the diagram. The collection side panel opens on the right side of the screen.

4. Delete the collection

   In the side panel, click the  icon.

## Next Steps

- [Modify Fields in Your Compass Entity-Relationship Diagram](https://www.mongodb.com/docs/compass/data-modeling/modify-fields.md#std-label-compass-modify-data-model-fields)

- [Manage Relationships in Your Compass Entity-Relationship Diagram](https://www.mongodb.com/docs/compass/data-modeling/relationships.md#std-label-compass-data-modeling-relationships)

- [Export Your Entity-Relationship Diagram from Compass](https://www.mongodb.com/docs/compass/data-modeling/export-diagram.md#std-label-compass-data-modeling-export)

- [Import an Entity-Relationship Diagram in Compass](https://www.mongodb.com/docs/compass/data-modeling/import-diagram.md#std-label-compass-data-modeling-import)

## Learn More

- [Data Modeling in MongoDB](https://www.mongodb.com/docs/manual/data-modeling.md#std-label-manual-data-modeling-intro)

- [Data Modeling in MongoDB Compass](https://www.mongodb.com/docs/compass/data-modeling.md#std-label-compass-data-modeling)