DA0-001 Comparing and Contrasting Data Concepts Practice Question
This DA0-001 practice question tests your understanding of comparing and contrasting data concepts. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is designing a data lake to store raw sensor data from IoT devices. The data arrives as JSON objects with varying schemas. Which storage approach is most appropriate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Store raw JSON files in a distributed file system and apply schema-on-read
Option D is correct because a data lake is designed to store raw data in its native format, and IoT sensor data with varying schemas is best handled by storing raw JSON files in a distributed file system (e.g., HDFS or Amazon S3). This approach leverages schema-on-read, where the schema is applied at query time rather than at write time, allowing flexibility for heterogeneous JSON objects without data loss or transformation overhead.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Ingest into a relational database with a predefined schema
Why it's wrong here
Relational databases require a fixed schema, incompatible with varying JSON.
✗
Store each JSON object as a separate file in a compressed columnar format
Why it's wrong here
Columnar formats like Parquet require a fixed schema, which is not suitable for varying JSON schemas.
✗
Convert all JSON to Avro with a fixed schema before storing
Why it's wrong here
Avro with fixed schema imposes schema-on-write, reducing flexibility.
✓
Store raw JSON files in a distributed file system and apply schema-on-read
Why this is correct
Schema-on-read allows handling varying schemas without upfront transformation.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse 'schema-on-read' with 'schema-on-write' and assume that converting to a structured format like Avro or columnar storage is always better for performance, ignoring the requirement to store raw, varying-schema data as-is.
Detailed technical explanation
How to think about this question
Schema-on-read is a core principle of data lakes, enabling tools like Apache Spark or Presto to infer or apply schemas dynamically when querying raw JSON files. In contrast, schema-on-write approaches (e.g., Avro, relational databases) require upfront schema definition, which is impractical for IoT data where device firmware updates can introduce new fields unpredictably. Real-world implementations often use partitioned directories (e.g., by date or device ID) to organize raw JSON files, allowing efficient pruning during queries without sacrificing flexibility.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Comparing and Contrasting Data Concepts — This question tests Comparing and Contrasting Data Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Store raw JSON files in a distributed file system and apply schema-on-read — Option D is correct because a data lake is designed to store raw data in its native format, and IoT sensor data with varying schemas is best handled by storing raw JSON files in a distributed file system (e.g., HDFS or Amazon S3). This approach leverages schema-on-read, where the schema is applied at query time rather than at write time, allowing flexibility for heterogeneous JSON objects without data loss or transformation overhead.
What should I do if I get this DA0-001 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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