My short-link stats API learned that 'is it dead?' is a different question than 'is it alive?'

Описание и применение

API коротких ссылок теперь различает три состояния: живые и кликнутые, живые и без клик, и удалённые, улучшая точность мониторинга и производительность.

Задача

The API returned 404 for both deleted links and links with zero clicks, making it impossible for callers to distinguish between a dead link and an alive but unused link.

Результат

The API now clearly distinguishes between alive‑and‑silent, alive‑and‑clicked, and gone links, preventing downstream retry loops, alerts, and dead‑letter queues from misinterpreting 404s as successful responses. Performance improved from O(n) to O(1) for click window calculations.

Рабочий процесс

• 1. Detect link existence and return 404 for deleted or expired links.
• 2. Return stats with last_click_at null for alive links that have never been clicked.
• 3. Return stats with last_click_at timestamp for links that have been clicked.
• 4. Use per‑link counters to compute 30‑day click windows in O(1).

Доказательства

A link with zero clicks and a link that was deleted look identical if you only check existence.

Источник

So I split the contract. last_click_at: null now means "alive, never clicked." A 404 means "gone or expired."

Источник

With per-link counters incremented on write, the stats call went from O(n) to O(1) and stopped timing out under burst traffic.

Источник