Amazon DynamoDB Interview Questions

1. What is Amazon DynamoDB and what problems does it solve?

2. What is the difference between DynamoDB and a relational database?

3. What is the difference between DynamoDB and MongoDB?

4. What is a partition key in DynamoDB and how does it distribute data?

5. What is the difference between a partition key and a sort key in DynamoDB?

6. What is a composite primary key in DynamoDB?

7. How does DynamoDB partitioning and data distribution work under the hood?

8. What are secondary indexes in DynamoDB (GSI vs LSI)?

9. When should you use a Global Secondary Index versus a Local Secondary Index?

10. What is read and write capacity in DynamoDB (provisioned vs on-demand)?

11. What are read capacity units and write capacity units in DynamoDB?

12. What is the difference between eventually consistent and strongly consistent reads in DynamoDB?

13. What is single-table design in DynamoDB and why is it recommended?

14. How do you model one-to-many and many-to-many relationships in DynamoDB?

15. What is the difference between Query and Scan operations in DynamoDB?

16. Why should you avoid Scan operations in DynamoDB?

17. What are DynamoDB Streams and what are they used for?

18. How does DynamoDB integrate with AWS Lambda for event-driven processing?

19. What is DynamoDB Time to Live (TTL) and when do you use it?

20. What is DynamoDB Accelerator (DAX) and how does it improve performance?

21. How does DynamoDB handle transactions (TransactWriteItems)?

22. What is optimistic locking in DynamoDB and how do conditional writes work?

23. What is a hot partition in DynamoDB and how do you avoid it?

24. How do you design partition keys for even data distribution in DynamoDB?

25. What are global tables in DynamoDB and how does multi-region replication work?

26. How does auto scaling work in DynamoDB?

27. How do you handle pagination in DynamoDB queries?

28. What are the item size limits and other quotas in DynamoDB?

29. When should you choose DynamoDB over other AWS databases?

30. What are common DynamoDB anti-patterns and best practices?

31. A production DynamoDB table is throttling — how do you diagnose and fix it?

32. How do you correctly handle UnprocessedItems in BatchWriteItem and UnprocessedKeys in BatchGetItem?

33. How do you configure AWS SDK retries and timeouts for a latency-sensitive DynamoDB client?

34. When would you choose Kinesis Data Streams for DynamoDB over DynamoDB Streams?

35. How can a global secondary index break writes to the base table, and how do you design around it?

36. How do you design a DynamoDB backup and restore strategy with PITR and on-demand backups?

37. Your DynamoDB bill is rising faster than traffic — how do you find and reduce the cost?

38. How do you restrict a caller to only their own DynamoDB items using IAM?

39. How do you test DynamoDB-backed code locally and in CI without weakening the tests?

40. How do you change a DynamoDB table's partition key with no downtime?

41. How do you run analytics over a DynamoDB table without hurting production traffic?

42. How do you harden a DynamoDB table for encryption, network isolation and auditability?

43. What are the real trade-offs of single-table design, and when would you not use it?

44. How does DynamoDB adaptive capacity work, and why can you still get throttled?

45. What is a sparse global secondary index and when would you reach for one?

46. What is index overloading in DynamoDB and what does it cost you?

47. How do you make DynamoDB writes idempotent using condition expressions?

48. What are the practical limits of DynamoDB transactions, and how do you handle a cancelled transaction?

49. What ordering guarantees do DynamoDB Streams give, and where do they end?

50. How do you build a DynamoDB Streams consumer that tolerates redelivery?

51. When does a DynamoDB TTL item actually disappear, and what must the application do about it?

52. How would you run a full table scan safely with parallel segments and make it resumable?

53. How do you estimate DynamoDB capacity for a new workload before it launches?

54. An item is approaching the 400 KB limit — how do you restructure it?

55. You restore a DynamoDB table from a backup — what does the restore not bring back?

56. A DynamoDB query is far more expensive than expected — how do you find out why?

57. What is the difference between a key condition and a filter expression, and why does it matter for cost?

58. How would you model high-volume time-series data in DynamoDB?

59. How do you maintain accurate counters and aggregates in DynamoDB?

60. How do you publish events reliably when writing to DynamoDB?

61. How would you keep a full version history of an item in DynamoDB?