My boss's SQL schema has no foreign keys and he said he left them out intentionally because they should be handled in the application layer and they're a large performance impact.

This is a fresh greenfield project and he's already pre-optimizing for problems we don't have yet, on things that may or not be bottlenecks using ideas (e.g. foreign keys have huge performance costs on mariadb/auora) with no hard data or facts to back them up.

Let's start a new project with some technical debt!