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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 ClassMin DurationRetrievalUse Case
S3 StandardNoneImmediateFrequently accessed data
S3 Standard-IA30 daysImmediateInfrequent access, rapid retrieval
S3 One Zone-IA30 daysImmediateNon-critical infrequent data
S3 Intelligent-TieringNoneImmediate–hoursUnknown or changing access patterns
S3 Glacier Instant90 daysMillisecondsArchive with instant retrieval
S3 Glacier Flexible90 daysMinutes–hoursArchive, flexible retrieval
S3 Glacier Deep Archive180 daysHoursLong-term compliance archive

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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.