Depends on your definition of large-scale, but I managed a 120K QPS MySQL 8.x cluster that heavily used FKs. After heavy optimization and parameter tuning, I wa

Depends on your definition of large-scale, but I managed a 120K QPS MySQL 8.x cluster that heavily used FKs. After heavy optimization and parameter tuning, I was also able to halve the instance size while improving query performance. I’m a big fan of FKs. They stop you from doing stupid shit, and if the time ever truly comes that you have to drop them, you can do so.