Using Cloud Firestore in Datastore Mode

Firestore is a NoSQL document database built for automatic scaling, high performance, and ease of application development. It is the newest version of Datastore and introduces several improvements over Datastore.

Because Firestore in Datastore mode is optimized for server use cases and for App Engine, we recommend using Firestore in Datastore mode for databases that will be used primarily by App Engine apps. Firestore in Native mode is most useful for mobile and real-time notification use cases. For more information about Firestore modes, see Choosing between Native Mode and Datastore mode.

Using Datastore mode with App Engine

To use Datastore mode with App Engine:

1. If you haven't already done so, create a database and choose Firestore in Datastore mode.

   You can use existing Datastore databases with App Engine apps. These existing databases will be automatically upgraded to Firestore in Datastore mode.

   1. In your app, declare Datastore as a dependency by using the go get cloud.google.com/go/datastore command. Alternatively, you can declare dependencies in your app's go.mod file. Learn more about specifying dependencies.

   2. Use the Google Cloud Client Library to read and write entities and to query data.

   Configuring indexes

   Datastore mode uses indexes for every query your application makes. The indexes are updated whenever an entity changes, so the results can be returned quickly when the app makes a query.

   Datastore mode automatically creates single-property indexes for use with simple types of queries. For complex queries that include multiple properties, you'll need to configure composite indexes in your app's index.yaml file.

   The App Engine development server will update your index.yaml file with the composite indexes needed to run your tests. Similarly, the Datastore mode emulator can generate indexes when you run tests.

   You can also add the indexes to your app's index.yaml file manually if you do not run local tests or your tests do not include complex queries.

   Setting database permissions

   By default, your app has all the permissions required to read and write to Datastore mode and Firestore databases in your Google Cloud project.

   To manage these permissions, each App Engine app uses a default service account that gives full read and write access to Datastore mode and Firestore databases in the same project as the app. You can change the permissions of the default service account, but your app may lose access unless you assign an IAM role with the required permissions.

   For information about allowing other users, apps, or projects to access a database, see Accessing your database.

   Using the Datastore mode emulator for local testing

   The Google Cloud CLI includes a local emulator of the production Datastore mode mode environment. You can use the emulator to develop and test your application locally. In addition, the emulator can help you generate indexes for your production Datastore mode mode instance and delete unneeded indexes.

   If you use the App Engine local development server to test your app, you can ensure that the server will use the Datastore mode emulator by setting the --support_datastore_emulator=true flag when starting the server.

   If you are using the Datastore mode emulator, dev_appserver will display:

   ... Using Cloud Datastore Emulator.
   

   Pricing, quotas, and limits

   Datastore mode offers a free quota with daily limits. Paid accounts offer unlimited storage, read, and write operations. More information is available on the Datastore Quotas page.