Comment by maherbeg

A few of us built nearly the exact same thing for a Hackathon which was fun. This definitely can work. There are a couple of other approaches too that are interesting like

  - xata - https://xata.io/blog/xatastor-zfs-nvme-of-for-millions-of-postgres-databases
  - neon - which has a more sophisticated architecture that builds abstractions at the Postgres layer

But separating compute and storage sucks and the performance you get out of EBS and friends is mediocre. The elasticity is nice, but if you have High Availability and can move instances around, you can still expand your cluster relatively easily, just not easily in an emergency scenario.