Have you ever accidentally deleted a production table before? If so, I doubt you’d do it again if you are able to learn from your mistakes. No hostilities required. Hire good people who are smart and capable of learning.
Even where I work now (that has almost no table constraints at all because there is no way to support them at our scale), we have tooling that prevents you from making dumb mistakes and alerting + backups if you manage to do it anyway. Having processes in place to deal with these kinds of issues, and tooling is. That's what I meant by "people problem." No constraint will keep a determined person from deleting the wrong thing (in fact, it might be worse if it cascades).
We had someone accidentally fight the "query nanny" once, thinking they were deleting a table in their dev environment... nope, they deleted a production table with hundreds of millions of rows. It took hours to complete the deletion, while all devs worked to delete the feature so we could restore from backup and revert our hacked out code. They still work there.
My point is, these are all "people problems" and no technology will save you from them. They might mitigate the issue, or slow people down to get them to realize what they are about to do ... but that is all you can really hope for. A constraint isn't necessarily required to provide that mitigation, but it helps when you can use them.
Thanks for clarifying, I had misinterpreted your statement.
I can see how at huge scales, DB constraints can be impossible to implement. But they do come (almost) for free in terms of development effort, whereas what you describe probably took a long time to implement.
I never said it did. Just that people tend to learn from their mistakes. Are there people who will make the same mistake different ways over and over again? Yep (I’m one of them). It’s not an issue, I learn and get better at spotting the mistake when I review other’s code and others point it out when reviewing my code. That’s why I said “exactly once” since once you know what it looks like, you can spot it in a review.
