Delayed Queue Reminders: Using a 7-Day Window and Worker Pool to Avoid Polling

The article explains how to schedule user reminders in an edtech app by splitting them into two horizons. Reminders due within seven days are placed on a delayed queue immediately, while later ones remain as database rows. A cron-based promoter moves rows into the queue once they enter the seven-day window, with the database serving as the source of truth. Because standard queues are at-least-once, the author stresses idempotency keys on both notification calls and database state changes. The code sample uses a vendor-neutral adapter so the reminder logic stays separate from the specific queue service.