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RED SAGSkills

Hard Backend Developer questions

32 questions · 20 points each for a correct first answer.

easymediumhard
  1. 1.Safe retries for paymentshard
  2. 2.CAP during a network partitionhard
  3. 3.Lost update on a wallet balancehard
  4. 4.Cache stampede on a hot keyhard
  5. 5.Saving to DB and publishing an eventhard
  6. 6.One slow route freezes Node.jshard
  7. 7.Connection pools and autoscalinghard
  8. 8.Why a lock alone is not enoughhard
  9. 9.NOT IN with a NULL in the listhard
  10. 10.Workers block each other on a jobs tablehard
  11. 11.Deadlocks between two transfershard
  12. 12.Two doctors go off call at oncehard
  13. 13.Account events processed out of orderhard
  14. 14.JWT verified with an attacker-chosen algorithmhard
  15. 15.Comparing secrets with ===hard
  16. 16.Retries stacked at every layerhard
  17. 17.Profile shows old data after savinghard
  18. 18.Adding a fifth cache nodehard
  19. 19.Sharding orders by creation datehard
  20. 20.Table bloat that VACUUM will not fixhard
  21. 21.Stale value returns after cache deletehard
  22. 22.Work continues after the client gives uphard
  23. 23.Trusting a Bloom filter answerhard
  24. 24.Index for the few pending rowshard
  25. 25.Inserts slow down with UUID keyshard
  26. 26.Burst at a fixed window boundaryhard
  27. 27.return versus return await in tryhard
  28. 28.Sorting by a user-chosen columnhard
  29. 29.Pool exhausted during paymentshard
  30. 30.Deep merge of untrusted JSONhard
  31. 31.Concurrent requests from throughputhard
  32. 32.Adding an index to a live big tablehard