From 8 GB to 24 MB: Scaling Real‑Time DAU to 200 M Users with Redis HyperLogLog
This article walks through the redesign of a high‑traffic, multi‑dimensional DAU counting system that grew from 8 GB of Redis Set memory to a 24 MB HyperLogLog‑based solution supporting 200 million daily active users, 40 k QPS, and flexible time‑window queries while keeping latency under 20 ms.
