Rails at Super Scale with Kyle d'Oliveira - RUBY 667

2967.682 - 2987.952 Kyle d'Oliveira

And a preload splits it off into a different query entirely, where you do something like select star from table, where ID is in this big list. But then there's eager load, which tries to smoosh it into one big query. This is something where Rails always suggests using includes because it'll handle that distinction for you. But that distinction actually makes a difference at scale.