How many orgs do you know that need to grow beyond a single machine let alone an indie developer? This post was from an indie developer not some big corp engineering blog. I don't know what you mean by partitioning, I'm assuming sharding and not partition/splitting of tables, because this approach is not mutually exclusive to that. MySQL and PostgreSQL can scale up very vertical if designed well. 99.99% or even more never need to scale horizontally. Nevertheless, this can be scaled horizontally carefully a bit. You grow your replicas. Your main DB will be your transactional DB. All procedures that are doing inserts/updates/deletes and select will call that DB. All non transactional SELECTS will call the read only replicas and treat those as your analytical. You can easily have something like one main DB, 3-5 read only DB. Add caching, Add queues and you can have a system that can serve 1+ million users daily.
