The tenants concept is really cool and something I'm fighting with right now. I actually went single-tenant from day 1 (not exactly on purpose) and it's a been a pain to find a DB solution that will work well for me.

I absolutely love PlanetScale but having 1 database per client means paying for 1 plan per client. I'm B2B so I have way fewer "clients" but my load is incredibly spiky for each client (75% of the time they have near-0 usage, 20% of the time they have a tiny amount of usage, and the 5% they use a bunch). As it stands right now their heavy load never overlaps so I've been mulling over a move to an RDS cluster where I can run multiple databases on the same hardware.

I'm not super interested in migrating to Postgres (though I think my app would move relatively easily, I don't use anything super MySQL-specific, it's just what I know) but I'll be watching this project as it moves forward. I'd really like to not manage my own DB, it's not where I'm strong and I'd rather focus on other things.