dbaplus Community

May 6, 2026 · Backend Development

Why Scheduled Tasks Fail for Million‑Scale Order Cancellation and How Redis Solves It

The article dissects a common interview question about automatically canceling unpaid orders after 30 minutes, explains why naïve cron‑based scans are unsuitable for tens of millions of rows, and presents three progressively robust solutions using Redis expiration, Redis ZSet polling, and message‑queue or time‑wheel architectures.