Subscription Commerce Analytics Path · Mission 11 of 25Hard

First event per subscription

First window function. Practice ROW_NUMBER() OVER (PARTITION BY subscription_id ORDER BY event_ts) — the foundational pattern for picking one row per entity from an event stream. Confirms a sanity invariant: every subscription's first event should be 'created'.

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The Brief

You'll practice

ROW_NUMBERPARTITION BYWindow
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All 25 missions in Subscription Commerce Analytics Path ↓
  1. 1. Snapshot inventory by plan
  2. 2. Active subscribers by country
  3. 3. MRR by plan family
  4. 4. Q3 2024 acquisition by channel
  5. 5. Q1 2026 cancelled subscriptions
  6. 6. Monthly active subscriber trend
  7. 7. 90-day cohort retention
  8. 8. Blended revenue: subs MRR plus one-time orders
  9. 9. ARPU by plan
  10. 10. Skip rate by plan family
  11. 11. First event per subscription
  12. 12. Event-derived current state
  13. 13. Find late-arriving events
  14. 14. Subscriptions with multiple skips
  15. 15. Plan migrations Q1 2026
  16. 16. MRR walk components — Q1 2026
  17. 17. Subscriber-vs-one-time blended LTV (matched cohort)
  18. 18. NRR by signup cohort
  19. 19. Churn forensics by reason_code (Q1 2026)
  20. 20. Pause-shaped cancellations cleanup
  21. 21. 12-month cohort decay curve
  22. 22. Resurrection identification
  23. 23. Snapshot-vs-event drift report
  24. 24. Subscriber LTV with one-time spillover
  25. 25. THE MRR WALK — opening + new + expansion − contraction − churn + resurrection = closing