It's been standard practice at all the companies I've worked at to index all foreign key fields, no matter what they're used for, I've yet to run into a situati

It's been standard practice at all the companies I've worked at to index all foreign key fields, no matter what they're used for, I've yet to run into a situation where it's been more harmful than helpful, but these companies all had <10TB data in SQL so idk if it's good general advice.