Databases come in two forms in App Platform: dev databases, which are not intended for production use, and managed databases (referred to as “existing databases” in the user interface), which are instances of a DigitalOcean managed database that you have created outside of App Platform and would like to use in production.
Dev databases only come in one size and will not scale well to handle traffic for your app. Additionally, your dev database permissions will not allow you to create databases; instead you will need to use the default database.
Managed databases have features like standby nodes, upscaling, and read-only nodes that add extra processing and throughput capacity for your database solution. To use a managed database, create one in your DigitalOcean account in the Cloud area of the control panel (outside of the Apps area) so that when you add a database component in App Platform, it shows up under the Existing Databases heading.