It's unrealistic to remove all joins (usually), and most joins aren't very expensive. In normal cases a join is strictly faster than running an extra query to

It's unrealistic to remove all joins (usually), and most joins aren't very expensive. In normal cases a join is strictly faster than running an extra query to get that extra data. Joins start getting particularly tricky when you do expensive stuff like filter over the correlated results of many tables. But in those cases, there's also no easy alternative: you'll need to redesign the way you store your data, if possible.