Spark Delta Lake Basics MCQ Questions with Answers (Latest 2026)

Q1. Which option best describes Delta Lake?

A. Open lakehouse format with ACID transactions. B. A pure CSV format. C. A pure index. D. A pure cache.

Select an answer to check.

Answer: Open lakehouse format with ACID transactions.

Here, Open lakehouse format with ACID transactions. is the right choice. JSON transaction log on Parquet. It aligns directly with what the question asks about which option best describes delta lake. A quick elimination of partially true options helps confirm it.

Q2. What is the primary purpose of Delta Lake?

A. A pure CSV format. B. A pure index. C. A pure cache. D. Open lakehouse format with ACID transactions.

Select an answer to check.

Answer: Open lakehouse format with ACID transactions.

In this case, Open lakehouse format with ACID transactions. is correct. JSON transaction log on Parquet. It aligns directly with what the question asks about what is the primary purpose of delta lake. A quick elimination of partially true options helps confirm it.

Q3. Which statement about Delta Lake is most accurate?

A. A pure cache. B. A pure CSV format. C. A pure index. D. Open lakehouse format with ACID transactions.

Select an answer to check.

Answer: Open lakehouse format with ACID transactions.

The best option here is Open lakehouse format with ACID transactions.. JSON transaction log on Parquet. It aligns directly with what the question asks about which statement about delta lake is most accurate. A quick elimination of partially true options helps confirm it.

Q4. How is Delta Lake best characterized?

A. A pure CSV format. B. Open lakehouse format with ACID transactions. C. A pure index. D. A pure cache.

Select an answer to check.

Answer: Open lakehouse format with ACID transactions.

For this question, Open lakehouse format with ACID transactions. is correct. JSON transaction log on Parquet. It aligns directly with what the question asks about how is delta lake best characterized. A quick elimination of partially true options helps confirm it.

Q5. Which option best describes the _delta_log?

A. A pure index. B. A pure schema file. C. A pure cache. D. Per-table directory of JSON commit logs.

Select an answer to check.

Answer: Per-table directory of JSON commit logs.

Per-table directory of JSON commit logs. is the correct answer here. Source of truth for table state. It aligns directly with what the question asks about which option best describes the _delta_log. A quick elimination of partially true options helps confirm it.

Q6. What is the primary purpose of the _delta_log?

A. A pure schema file. B. A pure index. C. A pure cache. D. Per-table directory of JSON commit logs.

Select an answer to check.

Answer: Per-table directory of JSON commit logs.

Here, Per-table directory of JSON commit logs. is the right choice. Source of truth for table state. This matches the core idea being tested around what is the primary purpose of the _delta_log. A quick elimination of partially true options helps confirm it.

Q7. Which statement about the _delta_log is most accurate?

A. A pure schema file. B. Per-table directory of JSON commit logs. C. A pure index. D. A pure cache.

Select an answer to check.

Answer: Per-table directory of JSON commit logs.

In this case, Per-table directory of JSON commit logs. is correct. Source of truth for table state. This matches the core idea being tested around which statement about the _delta_log is most accurate. A quick elimination of partially true options helps confirm it.

Q8. How is the _delta_log best characterized?

A. A pure schema file. B. A pure index. C. Per-table directory of JSON commit logs. D. A pure cache.

Select an answer to check.

Answer: Per-table directory of JSON commit logs.

The best option here is Per-table directory of JSON commit logs.. Source of truth for table state. This matches the core idea being tested around how is the _delta_log best characterized. A quick elimination of partially true options helps confirm it.

Q9. Which option best describes ACID on Delta?

A. Pure eventually consistent. B. Pure read-only. C. Pure best-effort. D. Atomic, consistent, isolated, durable writes.

Select an answer to check.

Answer: Atomic, consistent, isolated, durable writes.

For this question, Atomic, consistent, isolated, durable writes. is correct. Provided by transaction log. This matches the core idea being tested around which option best describes acid on delta. A quick elimination of partially true options helps confirm it.

Q10. What is the primary purpose of ACID on Delta?

A. Pure best-effort. B. Pure read-only. C. Atomic, consistent, isolated, durable writes. D. Pure eventually consistent.

Select an answer to check.

Answer: Atomic, consistent, isolated, durable writes.

Atomic, consistent, isolated, durable writes. is the correct answer here. Provided by transaction log. This matches the core idea being tested around what is the primary purpose of acid on. A quick elimination of partially true options helps confirm it.

Q11. Which statement about ACID on Delta is most accurate?

A. Pure best-effort. B. Atomic, consistent, isolated, durable writes. C. Pure eventually consistent. D. Pure read-only.

Select an answer to check.

Answer: Atomic, consistent, isolated, durable writes.

Here, Atomic, consistent, isolated, durable writes. is the right choice. Provided by transaction log. That is exactly the concept behind which statement about acid on delta is most in this context. A quick elimination of partially true options helps confirm it.

Q12. How is ACID on Delta best characterized?

A. Pure best-effort. B. Pure eventually consistent. C. Pure read-only. D. Atomic, consistent, isolated, durable writes.

Select an answer to check.

Answer: Atomic, consistent, isolated, durable writes.

In this case, Atomic, consistent, isolated, durable writes. is correct. Provided by transaction log. That is exactly the concept behind how is acid on delta best characterized in this context. A quick elimination of partially true options helps confirm it.

Q13. Which option best describes optimistic concurrency?

A. Pure single-writer. B. Pure pessimistic locking. C. Writers commit only if no conflicts. D. No concurrency.

Select an answer to check.

Answer: Writers commit only if no conflicts.

The best option here is Writers commit only if no conflicts.. Conflict detection on commit. That is exactly the concept behind which option best describes optimistic concurrency in this context. A quick elimination of partially true options helps confirm it.

Q14. What is the primary purpose of optimistic concurrency?

A. Pure single-writer. B. No concurrency. C. Writers commit only if no conflicts. D. Pure pessimistic locking.

Select an answer to check.

Answer: Writers commit only if no conflicts.

For this question, Writers commit only if no conflicts. is correct. Conflict detection on commit. That is exactly the concept behind what is the primary purpose of optimistic concurrency in this context. A quick elimination of partially true options helps confirm it.

Q15. Which statement about optimistic concurrency is most accurate?

A. Pure pessimistic locking. B. No concurrency. C. Pure single-writer. D. Writers commit only if no conflicts.

Select an answer to check.

Answer: Writers commit only if no conflicts.

Writers commit only if no conflicts. is the correct answer here. Conflict detection on commit. That is exactly the concept behind which statement about optimistic concurrency is most accurate in this context. A quick elimination of partially true options helps confirm it.

Q16. How is optimistic concurrency best characterized?

A. Pure pessimistic locking. B. No concurrency. C. Pure single-writer. D. Writers commit only if no conflicts.

Select an answer to check.

Answer: Writers commit only if no conflicts.

Here, Writers commit only if no conflicts. is the right choice. Conflict detection on commit. It fits the requirement in the prompt about how is optimistic concurrency best characterized. A quick elimination of partially true options helps confirm it.

Q17. Which option best describes snapshot isolation?

A. Read uncommitted. B. Read committed only. C. Readers see consistent table version. D. No isolation.

Select an answer to check.

Answer: Readers see consistent table version.

In this case, Readers see consistent table version. is correct. Default Delta semantics. It fits the requirement in the prompt about which option best describes snapshot isolation. A quick elimination of partially true options helps confirm it.

Q18. What is the primary purpose of snapshot isolation?

A. Read committed only. B. Readers see consistent table version. C. Read uncommitted. D. No isolation.

Select an answer to check.

Answer: Readers see consistent table version.

The best option here is Readers see consistent table version.. Default Delta semantics. It fits the requirement in the prompt about what is the primary purpose of snapshot isolation. A quick elimination of partially true options helps confirm it.

Q19. Which statement about snapshot isolation is most accurate?

A. Read committed only. B. Readers see consistent table version. C. Read uncommitted. D. No isolation.

Select an answer to check.

Answer: Readers see consistent table version.

For this question, Readers see consistent table version. is correct. Default Delta semantics. It fits the requirement in the prompt about which statement about snapshot isolation is most accurate. A quick elimination of partially true options helps confirm it.

Q20. How is snapshot isolation best characterized?

A. Read uncommitted. B. Read committed only. C. No isolation. D. Readers see consistent table version.

Select an answer to check.

Answer: Readers see consistent table version.

Readers see consistent table version. is the correct answer here. Default Delta semantics. It fits the requirement in the prompt about how is snapshot isolation best characterized. A quick elimination of partially true options helps confirm it.

Q21. Which option best describes time travel?

A. Query past versions/timestamps. B. A pure log. C. A pure backup. D. Pure rollback only.

Select an answer to check.

Answer: Query past versions/timestamps.

Here, Query past versions/timestamps. is the right choice. VERSION AS OF / TIMESTAMP AS OF. This is the most accurate statement for which option best describes time travel. A quick elimination of partially true options helps confirm it.

Q22. What is the primary purpose of time travel?

A. Pure rollback only. B. A pure log. C. Query past versions/timestamps. D. A pure backup.

Select an answer to check.

Answer: Query past versions/timestamps.

In this case, Query past versions/timestamps. is correct. VERSION AS OF / TIMESTAMP AS OF. This is the most accurate statement for what is the primary purpose of time travel. A quick elimination of partially true options helps confirm it.

Q23. Which statement about time travel is most accurate?

A. A pure log. B. A pure backup. C. Pure rollback only. D. Query past versions/timestamps.

Select an answer to check.

Answer: Query past versions/timestamps.

The best option here is Query past versions/timestamps.. VERSION AS OF / TIMESTAMP AS OF. This is the most accurate statement for which statement about time travel is most accurate. A quick elimination of partially true options helps confirm it.

Q24. How is time travel best characterized?

A. A pure backup. B. A pure log. C. Query past versions/timestamps. D. Pure rollback only.

Select an answer to check.

Answer: Query past versions/timestamps.

For this question, Query past versions/timestamps. is correct. VERSION AS OF / TIMESTAMP AS OF. This is the most accurate statement for how is time travel best characterized. A quick elimination of partially true options helps confirm it.

Q25. Which option best describes schema enforcement?

A. Pure log only. B. Pure inference. C. Always allow. D. Reject writes that don't match schema.

Select an answer to check.

Answer: Reject writes that don't match schema.

Reject writes that don't match schema. is the correct answer here. Prevents silent drift. This is the most accurate statement for which option best describes schema enforcement. A quick elimination of partially true options helps confirm it.

Q26. What is the primary purpose of schema enforcement?

A. Pure inference. B. Reject writes that don't match schema. C. Pure log only. D. Always allow.

Select an answer to check.

Answer: Reject writes that don't match schema.

Here, Reject writes that don't match schema. is the right choice. Prevents silent drift. It aligns directly with what the question asks about what is the primary purpose of schema enforcement. The other options are either incomplete or contextually incorrect.

Q27. Which statement about schema enforcement is most accurate?

A. Pure inference. B. Reject writes that don't match schema. C. Always allow. D. Pure log only.

Select an answer to check.

Answer: Reject writes that don't match schema.

In this case, Reject writes that don't match schema. is correct. Prevents silent drift. It aligns directly with what the question asks about which statement about schema enforcement is most accurate. The other options are either incomplete or contextually incorrect.

Q28. How is schema enforcement best characterized?

A. Always allow. B. Reject writes that don't match schema. C. Pure inference. D. Pure log only.

Select an answer to check.

Answer: Reject writes that don't match schema.

The best option here is Reject writes that don't match schema.. Prevents silent drift. It aligns directly with what the question asks about how is schema enforcement best characterized. The other options are either incomplete or contextually incorrect.

Q29. Which option best describes schema evolution?

A. Always blocked. B. Add columns with mergeSchema=true. C. Pure CSV only. D. Pure manual ALTER only.

Select an answer to check.

Answer: Add columns with mergeSchema=true.

For this question, Add columns with mergeSchema=true. is correct. Controlled evolution. It aligns directly with what the question asks about which option best describes schema evolution. The other options are either incomplete or contextually incorrect.

Q30. What is the primary purpose of schema evolution?

A. Pure CSV only. B. Add columns with mergeSchema=true. C. Pure manual ALTER only. D. Always blocked.

Select an answer to check.

Answer: Add columns with mergeSchema=true.

Add columns with mergeSchema=true. is the correct answer here. Controlled evolution. It aligns directly with what the question asks about what is the primary purpose of schema evolution. The other options are either incomplete or contextually incorrect.

Q31. Which statement about schema evolution is most accurate?

A. Always blocked. B. Pure manual ALTER only. C. Pure CSV only. D. Add columns with mergeSchema=true.

Select an answer to check.

Answer: Add columns with mergeSchema=true.

Here, Add columns with mergeSchema=true. is the right choice. Controlled evolution. This matches the core idea being tested around which statement about schema evolution is most accurate. The other options are either incomplete or contextually incorrect.

Q32. How is schema evolution best characterized?

A. Add columns with mergeSchema=true. B. Always blocked. C. Pure CSV only. D. Pure manual ALTER only.

Select an answer to check.

Answer: Add columns with mergeSchema=true.

In this case, Add columns with mergeSchema=true. is correct. Controlled evolution. This matches the core idea being tested around how is schema evolution best characterized. The other options are either incomplete or contextually incorrect.

Q33. Which option best describes MERGE INTO (Delta)?

A. UPDATE only. B. Atomic upsert/delete by condition. C. DELETE only. D. INSERT only.

Select an answer to check.

Answer: Atomic upsert/delete by condition.

The best option here is Atomic upsert/delete by condition.. Foundational for CDC. This matches the core idea being tested around which option best describes merge into (delta). The other options are either incomplete or contextually incorrect.

Q34. What is the primary purpose of MERGE INTO (Delta)?

A. UPDATE only. B. DELETE only. C. INSERT only. D. Atomic upsert/delete by condition.

Select an answer to check.

Answer: Atomic upsert/delete by condition.

For this question, Atomic upsert/delete by condition. is correct. Foundational for CDC. This matches the core idea being tested around what is the primary purpose of merge into. The other options are either incomplete or contextually incorrect.

Q35. Which statement about MERGE INTO (Delta) is most accurate?

A. DELETE only. B. INSERT only. C. UPDATE only. D. Atomic upsert/delete by condition.

Select an answer to check.

Answer: Atomic upsert/delete by condition.

Atomic upsert/delete by condition. is the correct answer here. Foundational for CDC. This matches the core idea being tested around which statement about merge into (delta) is most. The other options are either incomplete or contextually incorrect.

Q36. How is MERGE INTO (Delta) best characterized?

A. INSERT only. B. DELETE only. C. UPDATE only. D. Atomic upsert/delete by condition.

Select an answer to check.

Answer: Atomic upsert/delete by condition.

Here, Atomic upsert/delete by condition. is the right choice. Foundational for CDC. That is exactly the concept behind how is merge into (delta) best characterized in this context. The other options are either incomplete or contextually incorrect.

Q37. Which option best describes UPDATE/DELETE?

A. Append-only only. B. Row-level mutations on Delta tables. C. Pure log. D. Pure SELECT.

Select an answer to check.

Answer: Row-level mutations on Delta tables.

In this case, Row-level mutations on Delta tables. is correct. Lakehouse SQL. That is exactly the concept behind which option best describes update/delete in this context. The other options are either incomplete or contextually incorrect.

Q38. What is the primary purpose of UPDATE/DELETE?

A. Pure log. B. Append-only only. C. Pure SELECT. D. Row-level mutations on Delta tables.

Select an answer to check.

Answer: Row-level mutations on Delta tables.

The best option here is Row-level mutations on Delta tables.. Lakehouse SQL. That is exactly the concept behind what is the primary purpose of update/delete in this context. The other options are either incomplete or contextually incorrect.

Q39. Which statement about UPDATE/DELETE is most accurate?

A. Row-level mutations on Delta tables. B. Append-only only. C. Pure SELECT. D. Pure log.

Select an answer to check.

Answer: Row-level mutations on Delta tables.

For this question, Row-level mutations on Delta tables. is correct. Lakehouse SQL. That is exactly the concept behind which statement about update/delete is most accurate in this context. The other options are either incomplete or contextually incorrect.

Q40. How is UPDATE/DELETE best characterized?

A. Row-level mutations on Delta tables. B. Pure log. C. Append-only only. D. Pure SELECT.

Select an answer to check.

Answer: Row-level mutations on Delta tables.

Row-level mutations on Delta tables. is the correct answer here. Lakehouse SQL. That is exactly the concept behind how is update/delete best characterized in this context. The other options are either incomplete or contextually incorrect.

Q41. Which option best describes OPTIMIZE?

A. A pure index rebuild. B. Compact small files into larger ones. C. A pure schema change. D. A pure backup.

Select an answer to check.

Answer: Compact small files into larger ones.

Here, Compact small files into larger ones. is the right choice. Improves scan performance. It fits the requirement in the prompt about which option best describes optimize. The other options are either incomplete or contextually incorrect.

Q42. What is the primary purpose of OPTIMIZE?

A. A pure index rebuild. B. A pure backup. C. Compact small files into larger ones. D. A pure schema change.

Select an answer to check.

Answer: Compact small files into larger ones.

In this case, Compact small files into larger ones. is correct. Improves scan performance. It fits the requirement in the prompt about what is the primary purpose of optimize. The other options are either incomplete or contextually incorrect.

Q43. Which statement about OPTIMIZE is most accurate?

A. A pure schema change. B. A pure index rebuild. C. A pure backup. D. Compact small files into larger ones.

Select an answer to check.

Answer: Compact small files into larger ones.

The best option here is Compact small files into larger ones.. Improves scan performance. It fits the requirement in the prompt about which statement about optimize is most accurate. The other options are either incomplete or contextually incorrect.

Q44. How is OPTIMIZE best characterized?

A. A pure schema change. B. Compact small files into larger ones. C. A pure index rebuild. D. A pure backup.

Select an answer to check.

Answer: Compact small files into larger ones.

For this question, Compact small files into larger ones. is correct. Improves scan performance. It fits the requirement in the prompt about how is optimize best characterized. The other options are either incomplete or contextually incorrect.

Q45. Which option best describes Z-ORDER BY?

A. Random clustering. B. Pure partitioning only. C. Cluster files on columns. D. Pure indexing only.

Select an answer to check.

Answer: Cluster files on columns.

Cluster files on columns. is the correct answer here. Speeds selective queries. It fits the requirement in the prompt about which option best describes z-order by. The other options are either incomplete or contextually incorrect.

Q46. What is the primary purpose of Z-ORDER BY?

A. Pure indexing only. B. Cluster files on columns. C. Pure partitioning only. D. Random clustering.

Select an answer to check.

Answer: Cluster files on columns.

Here, Cluster files on columns. is the right choice. Speeds selective queries. This is the most accurate statement for what is the primary purpose of z-order by. The other options are either incomplete or contextually incorrect.

Q47. Which statement about Z-ORDER BY is most accurate?

A. Random clustering. B. Pure partitioning only. C. Cluster files on columns. D. Pure indexing only.

Select an answer to check.

Answer: Cluster files on columns.

In this case, Cluster files on columns. is correct. Speeds selective queries. This is the most accurate statement for which statement about z-order by is most accurate. The other options are either incomplete or contextually incorrect.

Q48. How is Z-ORDER BY best characterized?

A. Random clustering. B. Pure partitioning only. C. Pure indexing only. D. Cluster files on columns.

Select an answer to check.

Answer: Cluster files on columns.

The best option here is Cluster files on columns.. Speeds selective queries. This is the most accurate statement for how is z-order by best characterized. The other options are either incomplete or contextually incorrect.

Q49. Which option best describes VACUUM?

A. Remove unreferenced files past retention. B. A pure compaction. C. A pure schema change. D. A pure backup.

Select an answer to check.

Answer: Remove unreferenced files past retention.

For this question, Remove unreferenced files past retention. is correct. Required for cost; respects retention. This is the most accurate statement for which option best describes vacuum. The other options are either incomplete or contextually incorrect.

Q50. What is the primary purpose of VACUUM?

A. A pure schema change. B. Remove unreferenced files past retention. C. A pure compaction. D. A pure backup.

Select an answer to check.

Answer: Remove unreferenced files past retention.

Remove unreferenced files past retention. is the correct answer here. Required for cost; respects retention. This is the most accurate statement for what is the primary purpose of vacuum. The other options are either incomplete or contextually incorrect.