> A database doesn't know which data is most likely to be used again, but if does know which pages are guaranteed to not be used again because they're not reach

> A database doesn't know which data is most likely to be used again, but if does know which pages are guaranteed to not be used again because they're not reachable in the b+tree. This is true, but it may not be as helpful as it initially seems. Because it is very likely the the next mutation then writes to this unused page. So the window where that page is wasting cache capacity is quite small.