This is because Rails otherwise has no way of knowing which one is a replicaĪnd which one is the writer. When using a replica database, you need to add a replica: true entry to the replica in theĭatabase.yml. Replica user's database permissions should be set to only read and not write. Second, the username for the writers and replicas should be different, and the This is also the case for animals and animals_replica. When using multiple databases, there are a few important settings.įirst, the database name for the primary and primary_replica should be the same because they contain Production : primary : database : my_primary_database username : root password : adapter : mysql2 primary_replica : database : my_primary_database username : root_readonly password : adapter : mysql2 replica : true animals : database : my_animals_database username : animals_root password : adapter : mysql2 migrations_paths : db/animals_migrate animals_replica : database : my_animals_database username : animals_readonly password : adapter : mysql2 replica : true Copy

New database for some new tables we're adding. Let's say we have an application with a single writer database and we need to add a Need to do to get your application ready for multiple databases. While Rails tries to do most of the work for you there are still some steps you'll The following features are not (yet) supported:

Rails tasks for creating, dropping, migrating, and interacting with the multiple.

Automatic swapping between the writer and replica depending on the HTTP verb.

Automatic connection switching for the model you're working with.

Multiple writer databases and a replica for each.

So you don't have to store your data all in one place.Īt this time the following features are supported:

Rails now has support for multiple databases One way in which your application may need To support your new users and their data. As an application grows in popularity and usage you'll need to scale the application

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