Currently in the process of migrating a local app (custom sync) to MongoDb Realm. As a part of this I am doing database migrations to make the current schema better suited for sync, which makes it possible to migrate gradually.
In the old schemas, all primary keys are strings. In MongoDb Realm it is allowed to use Strings, Int or ObjectId. Is there any difference between them? Do I loose anything if I keep using strings instead of ObjectIId?