> I'm pretty sure cache invalidation is the harder of the two, because of some underlying OCD most of us have about picking two arbitrary constants that dictate

> I'm pretty sure cache invalidation is the harder of the two, because of some underlying OCD most of us have about picking two arbitrary constants that dictate sweep frequency and TTL. I'd even go as far as to speculate most of the evolution of programming has been a weird spiritual exercise around trying not to pick those two arbitrary numbers. Functional programming as a whole can even be understood as a set of taboos around this, because what good is shared OCD if it doesn't lead to religion. Can someone explain this? What numbers?