I've been wondering what the backing store model is for Gmail, specifically its snooze functionality. More specifically, when you snooze multiple items to the same time they do not preserve any meaningful listing order, i.e., they do not preserve the sequence in which they were snoozed (if done individually) or their relative position in the inbox.
Arbitrary ordering suggests it might be a hash, which seems overkill for something that would be as efficient and more usable as a sequence.