The answer is Amazon S3 with Amazon Athena. This is the most cost-effective choice because the semi-structured JSON logs are rarely updated and infrequently accessed, making S3’s low-cost object storage ideal for static data, while Athena’s serverless, pay-per-query model eliminates the need for any running cluster or provisioned capacity. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your ability to match storage and query services to data characteristics—specifically, that infrequent, ad-hoc SQL queries on archival JSON logs should avoid the fixed costs of Redshift, RDS, or DynamoDB. A common trap is choosing a database service for “SQL querying” without considering access patterns; remember, if the data sits still and you only query it occasionally, S3 plus Athena is your cheapest pair. Memory tip: “Still logs, small costs—S3 and Athena for the win.”
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 data engineer needs to store semi-structured JSON log files from multiple sources and query them using SQL. The data is rarely updated and access frequency is low. Which storage solution is MOST cost-effective?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon S3 with Amazon Athena for querying.
Amazon S3 with Athena is the most cost-effective solution because the data is semi-structured JSON, rarely updated, and accessed infrequently. S3 provides low-cost storage for static data, and Athena uses a serverless, pay-per-query model, eliminating the need for a running cluster or provisioned capacity. This combination avoids the fixed costs of Redshift, DynamoDB, or RDS, making it ideal for low-frequency SQL querying of archival logs.
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.
✗
Amazon Redshift with JSON ingestion and compression.
Why it's wrong here
Redshift is more expensive and designed for high-performance analytics, not low-cost archival storage.
✗
Amazon DynamoDB with JSON documents.
Why it's wrong here
DynamoDB is optimized for high-throughput workloads and is more expensive than S3 for archival data.
✓
Amazon S3 with Amazon Athena for querying.
Why this is correct
S3 provides cheap storage and Athena allows serverless SQL queries, ideal for low-frequency access.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon RDS for PostgreSQL with JSONB columns.
Why it's wrong here
RDS is a managed relational database with ongoing costs, not optimal for rarely queried data.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose Redshift or RDS because they associate SQL querying with traditional databases, overlooking that Athena's serverless, pay-per-query model is far more cost-effective for infrequent access to static data stored in S3.
Detailed technical explanation
How to think about this question
Athena leverages Presto under the hood to execute SQL queries directly on data stored in S3, using a schema-on-read approach that avoids the need for ETL or schema definition at write time. For JSON logs, Athena can automatically infer the schema using SerDe libraries (e.g., Hive JSON SerDe) and supports columnar formats like Parquet or ORC for further cost reduction via compression and predicate pushdown. In real-world scenarios, this pattern is often used for centralized logging (e.g., AWS CloudTrail logs) where data is immutable and queried only for compliance or troubleshooting.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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.
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Amazon S3 with Amazon Athena for querying. — Amazon S3 with Athena is the most cost-effective solution because the data is semi-structured JSON, rarely updated, and accessed infrequently. S3 provides low-cost storage for static data, and Athena uses a serverless, pay-per-query model, eliminating the need for a running cluster or provisioned capacity. This combination avoids the fixed costs of Redshift, DynamoDB, or RDS, making it ideal for low-frequency SQL querying of archival logs.
What should I do if I get this DEA-C01 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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This DEA-C01 practice question is part of Courseiva's free Amazon Web Services 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 DEA-C01 exam.
Question Discussion
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