[Dave3of5]

> we opted for having one DB per tenant which also makes sharding, scaling, balancing, and handling data-residency challenges easier

When you say 1 DB I suspect you mean you have a single DB Server and multiple DB's on that server. Then I don't think this really solves the data-residency problem as the clients data is just in a different DB but still on the same instance. It makes other problems for you as well for example you now have 2 DB's to run maintenance, upgrades, data migrations on. Current company uses a similar model for multiple types of systems and it makes upgrading the software very difficult.

It also makes scaling more difficult as instead of having a single DB cluster that you can tweek for everyone you'll need to tweek each cluster individually depending on the tenants that are on those clusters. You also have a practical limit to how many DB's you can have on any physical instance so your load balancing will become very tricky.

There are other problems it causes like federation which Enterprise Customers often want.