I assume you mean "performance overhead"? For insert-heavy workloads the difference very much is not "very minimal". In a quick test it's ~100ms vs. ~20ms with

I assume you mean "performance overhead"? For insert-heavy workloads the difference very much is not "very minimal". In a quick test it's ~100ms vs. ~20ms with two foreign keys which check against a "countries" table (250 rows) – one column for nationality and one for residence. ±a lot because this is a very quick test I ran just twice, but it fits what I measured before when I very much ran in to this performance penalty a few years back. And look, 20ms vs. 100ms is very much fine for a lot of use cases. But it's also not for a lot of others. And it's certainly not very minimal, and with many inserts it does amplify a lot.