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 (Datastore) is optimized for server use cases and for App Engine, we recommend using 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:
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.
In your app, declare Datastore as a dependency by adding the library to your app's dependencies file.
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 for Java includes a local development server for testing your application on your computer. The local development server emulates the App Engine Java runtime environment and all of its services, including Datastore mode.
The development server generates configuration for Datastore mode indexes needed by your application, determined from the queries it performs while you are testing it.
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.