From 32KB SQL Joins to 46 Bytes: Architecting an O(1) Habit Streak Engine with Valkey/Redis Bitmaps & POPCNT

How Duong Phuc Khanh (Kido) replaced bloated relational habit logs with 46-byte Redis/Valkey Bitmaps and CPU hardware POPCNT instructions, dropping p99 streak latency from 140ms to 0.08ms.