ARA-C01 Data Engineering Practice Question
An e-commerce company wants to analyze JSON data stored in an external stage on Amazon S3. The JSON files contain nested arrays and objects, and the schema varies between files. The architect needs to query this data with Snowflake while minimizing data duplication and storage costs. Which approach should the architect recommend?
⚠ Common exam trap
The trap here is assuming that loading JSON into a Snowflake table is necessary for querying with FLATTEN, but external tables support VARIANT and FLATTEN directly.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create an external table with a VARIANT column and use the FLATTEN function to query nested elements.
External tables with a VARIANT column allow direct querying of JSON in the external stage without loading, avoiding duplication and storage costs. FLATTEN handles nested structures. This is the most efficient approach for variable-schema JSON when the goal is to minimize data movement and storage, unlike loading into a table or using materialized views.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create a materialized view over the external stage that shreds the JSON into relational columns.
Why it's wrong here
Materialized views cannot be created directly over an external stage; they require a base table. Even if a base table existed, materializing shredded JSON would duplicate data and add storage and maintenance costs. This approach is not feasible as described and does not meet the minimization of duplication and storage.
- ✓
Create an external table with a VARIANT column and use the FLATTEN function to query nested elements.
Why this is correct
External tables allow querying data directly from the external stage without loading it into Snowflake, avoiding duplication and storage costs. Using a VARIANT column accommodates the semi-structured and variable schema, and FLATTEN enables querying nested arrays and objects. This approach meets the requirement to analyze JSON data while minimizing data movement and storage.
- ✗
Use a directory table and a stored procedure to parse and insert JSON into a relational table.
Why it's wrong here
A directory table provides file-level metadata but does not enable direct querying of JSON content. Using a stored procedure to parse and insert duplicates the data into Snowflake, incurring storage costs and adding complexity. This does not minimize duplication and is not a direct query solution.
- ✗
Load the JSON files into a Snowflake table with a VARIANT column using COPY INTO, then query with FLATTEN.
Why it's wrong here
Loading the data into a Snowflake table duplicates the data and incurs storage costs, which the requirement explicitly aims to minimize. While this approach simplifies querying and may improve performance, it does not satisfy the cost and duplication constraints. The architect should prefer a solution that queries data in place.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Snowflake exam blueprint
This ARA-C01 practice question is part of Courseiva's free Snowflake certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ARA-C01 exam.