Databricks Certified Data Engineer Associate Practice Questions: Delta Lake and Data Management Domain

Published: July 30, 2025 | 20 min read

Test your Databricks Certified Data Engineer Associate knowledge with 10 practice questions from the Delta Lake and Data Management domain. Includes detailed explanations and answers.

Databricks Certified Data Engineer Associate Practice Questions

Master the Delta Lake and Data Management Domain

Test your knowledge in the Delta Lake and Data Management domain with these 10 practice questions. Each question is designed to help you prepare for the Databricks Certified Data Engineer Associate certification exam with detailed explanations to reinforce your learning.

Question 1

Which command is used to create a Delta Lake table in Databricks?

A) CREATE DELTA TABLE

B) CREATE TABLE USING DELTA

C) CREATE TABLE AS DELTA

D) CREATE DELTA AS TABLE

Show Answer & Explanation

Correct Answer: B

Explanation: The correct syntax to create a Delta Lake table in Databricks is 'CREATE TABLE USING DELTA'. Options A, C, and D do not represent the correct syntax for this operation.

Question 2

What is a potential drawback of using Delta Lake's time travel feature extensively?

A) It can lead to increased storage costs.

B) It can cause data loss if not configured properly.

C) It can slow down query performance due to complex indexing.

D) It requires frequent schema updates.

Show Answer & Explanation

Correct Answer: A

Explanation: Using time travel extensively can increase storage costs because it retains historical versions of data. Option B is incorrect because time travel does not inherently cause data loss. Option C is incorrect because time travel itself does not slow down queries; performance depends on other factors. Option D is incorrect as time travel does not require schema updates.

Question 3

What is the primary use of Delta Lake's 'MERGE' operation?

A) To combine multiple tables into one

B) To update and insert data based on conditions

C) To remove duplicates from a table

D) To backup data to an external location

Show Answer & Explanation

Correct Answer: B

Explanation: The MERGE operation in Delta Lake is primarily used to update and insert data based on specified conditions, effectively handling upserts. Option A is incorrect because MERGE does not combine tables. Option C is incorrect because MERGE is not used for removing duplicates. Option D is incorrect because MERGE does not involve backing up data.

Question 4

Which command in Delta Lake is used to compact small files into larger ones to improve performance?

A) VACUUM

B) MERGE

C) OPTIMIZE

D) CLEAN

Show Answer & Explanation

Correct Answer: C

Explanation: The OPTIMIZE command in Delta Lake is used to compact small files into larger ones, which can improve read performance by reducing the number of files that need to be accessed. Option A, VACUUM, is used to remove old data files that are no longer needed. Option B, MERGE, is used to update and insert data. Option D, CLEAN, is not a Delta Lake command.

Question 5

How does Delta Lake handle data versioning?

A) By creating snapshots of the entire dataset periodically.

B) By maintaining a transaction log that records changes.

C) By storing multiple copies of the data.

D) By using an external version control system.

Show Answer & Explanation

Correct Answer: B

Explanation: Delta Lake handles data versioning through a transaction log that records all changes made to the data. Option A is incorrect because Delta Lake does not create snapshots of the entire dataset. Option C is incorrect as Delta Lake does not store multiple copies of the data. Option D is incorrect because Delta Lake does not rely on external version control systems.

Question 6

Which Delta Lake feature helps in maintaining data quality by preventing bad data from being written?

A) Time Travel

B) Schema Enforcement

C) Data Caching

D) Data Lineage

Show Answer & Explanation

Correct Answer: B

Explanation: Schema Enforcement in Delta Lake helps maintain data quality by preventing data that does not match the schema from being written. Option A, Time Travel, allows access to historical data but does not prevent bad data. Option C, Data Caching, is for performance, not data quality. Option D, Data Lineage, tracks data origins and transformations but does not prevent bad data.

Question 7

Which feature of Delta Lake helps in reducing the size of data files?

A) Schema enforcement

B) Data compaction

C) ACID transactions

D) Time travel

Show Answer & Explanation

Correct Answer: B

Explanation: Data compaction in Delta Lake helps reduce the size of data files by merging smaller files into larger ones, improving storage efficiency and query performance. Schema enforcement, ACID transactions, and time travel serve different purposes.

Question 8

What does Delta Lake use to ensure ACID transactions?

A) Distributed locks

B) Write-ahead logs

C) Snapshot isolation

D) Two-phase commit protocol

Show Answer & Explanation

Correct Answer: C

Explanation: Delta Lake uses snapshot isolation to ensure ACID transactions, which allows multiple readers and writers to operate simultaneously without interference. Option A, distributed locks, are not used in Delta Lake. Option B, write-ahead logs, are a concept from databases like HBase and are not used in Delta Lake. Option D, two-phase commit protocol, is a distributed transaction protocol not specifically used by Delta Lake.

Question 9

Which feature of Delta Lake allows you to view data as it existed at a previous point in time?

A) Schema Evolution

B) Time Travel

C) Data Lineage

D) Data Caching

Show Answer & Explanation

Correct Answer: B

Explanation: Time Travel is a feature of Delta Lake that allows users to query previous versions of the data. This is useful for auditing and debugging. Option A, Schema Evolution, refers to the ability to change the schema of a table over time. Option C, Data Lineage, is about tracking data's origin and transformations, not retrieving past data states. Option D, Data Caching, is about storing data in memory for faster access, not related to historical data views.

Question 10

In Delta Lake, what is the purpose of the 'OPTIMIZE' command?

A) To increase the storage capacity of the Delta Lake.

B) To compact small files into larger ones for better performance.

C) To delete outdated versions of data.

D) To automatically update the schema of a Delta table.

Show Answer & Explanation

Correct Answer: B

Explanation: The 'OPTIMIZE' command in Delta Lake is used to compact small files into larger ones, which improves query performance. Option A is incorrect as 'OPTIMIZE' does not affect storage capacity. Option C is incorrect because 'OPTIMIZE' does not delete data. Option D is incorrect because 'OPTIMIZE' does not update schemas.

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About Databricks Certified Data Engineer Associate Certification

The Databricks Certified Data Engineer Associate certification validates your expertise in delta lake and data management and other critical domains. Our comprehensive practice questions are carefully crafted to mirror the actual exam experience and help you identify knowledge gaps before test day.