architecture The Five-Minute Rule: A Heuristic for Deciding What Belongs in Cache josedacruz, October 24, 2026October 24, 2026 TL;DR: The “five-minute rule” is an old database heuristic that says: cache something if the cost of keeping it in memory is lower than the cost of re-fetching it, given how often it gets used. The actual “five minutes” number from the 1980s doesn’t matter anymore — what still matters… Continue Reading