A team of data analysts is using Amazon Athena to query data in S3. You notice that query costs are rising rapidly because they are performing 'full scans' of large CSV files. What is the most effective architectural change to reduce query costs and improve performance?

Direct Answer (Verified)Reviewed by Sunny (Senior Cloud Engineer)

Correct Answer: Convert the data to a columnar format like Parquet or ORC and partition it by date

Columnar formats like Parquet allow Athena to only read the specific columns required for a query. Partitioning allows it to skip entire folders of data that don't match the query ...

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Real Exam ScenarioAmazon S3

A team of data analysts is using Amazon Athena to query data in S3. You notice that query costs are rising rapidly because they are performing 'full scans' of large CSV files. What is the most effective architectural change to reduce query costs and improve performance?

✓ Correct Answer & ExplanationAmazon S3

Correct Answer

Convert the data to a columnar format like Parquet or ORC and partition it by date

Why This Answer Is Correct

Columnar formats like Parquet allow Athena to only read the specific columns required for a query. Partitioning allows it to skip entire folders of data that don't match the query criteria.

📚 What This Question Tests

This question evaluates your knowledge of Amazon S3 — a core concept tested in AWS Certified Solutions Architect – Professional (SAP-C02). Understanding Amazon S3 is essential for designing scalable, secure, and cost-effective cloud architectures. Mastery of this topic will help you answer scenario-based questions confidently on exam day.