easy Drill: daily & peak QPS for a social feed
Drill
A social app has 20M daily active users, each opening their feed 10 times/day. Estimate the average and peak read QPS. Try it before opening the solution.
Anchors: 86,400 ≈ 10⁵ s/day; peak factor ~2–3×.
✅ Worked solution & bounds check
Worked solution
- Requests/day = 20M × 10 = 2 × 10⁸.
- Average QPS = 2 × 10⁸ ÷ 10⁵ = ~2,000 QPS.
- Peak ×3 ≈ ~6,000 QPS.
Bounds: low (peak ×2) ≈ 4K; high (×5, bursty) ≈ 10K. Ratio 2.5× — tight, trustworthy.
Gate: ~6K read QPS is comfortably served by a few cached app servers; no exotic architecture needed yet.
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