Foreign keys are expensive is an oft repeated rarely benched claim. There are tons of ways to do it incorrectly. But in your stack you are always enforcing inte

Foreign keys are expensive is an oft repeated rarely benched claim. There are tons of ways to do it incorrectly. But in your stack you are always enforcing integrity _somewhere_ anyway. Leveraging the database instead of reimplementing it requires knowledge and experimentation, and it more often than not it will save your bacon.