DEA-C01 Data Store Management Practice Question
A data engineer is migrating an on-premises Apache Hive data warehouse to Amazon EMR. The warehouse contains partitioned tables stored in HDFS. The engineer wants to use Amazon S3 as the storage layer for the EMR cluster. What is the MOST important consideration for maintaining query performance on S3?
⚠ Common exam trap
The trap here is that candidates may focus on metastore performance (Option C) or alternative query engines (Option D), missing the fundamental S3 performance bottleneck of LIST requests when querying partitioned data on EMR.
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
✓
Ensure that the table partitions are organized in a way that minimizes S3 LIST requests
When using Amazon S3 as the storage layer for an EMR cluster, the most critical factor for query performance is minimizing S3 LIST requests. S3 LIST operations are significantly slower and more expensive than GET requests, and Hive/Spark queries on partitioned tables often issue LIST requests to discover partition locations. By organizing partitions with a common prefix (e.g., `year=2023/month=01/day=15/`) and using partition pruning, you reduce the number of LIST calls, directly improving query latency and reducing S3 API costs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Ensure that the table partitions are organized in a way that minimizes S3 LIST requests
Why this is correct
S3 LIST operations are slower than HDFS; partitioning by common query filters and using partition projection can improve performance.
- ✗
Configure EMR to use HDFS for storage instead of S3 for better performance
Why it's wrong here
HDFS is ephemeral; the migration is to S3 for durability.
- ✗
Use DynamoDB as the Hive metastore to improve metadata access
Why it's wrong here
The Hive metastore can be in MySQL or external, but DynamoDB is not standard for Hive.
- ✗
Use Amazon Redshift Spectrum to query the data directly from S3
Why it's wrong here
Redshift Spectrum is separate from EMR; the question is about EMR.
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 |
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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.