DBS-C01 Workload-Specific Database Design Practice Question
A company runs a critical OLTP workload on Amazon RDS for PostgreSQL. The database size is 2 TB and growing. To reduce storage costs, the company wants to archive old data that is rarely accessed. Which approach is most cost-effective and minimally impacts performance?
⚠ Common exam trap
Candidates often assume deleting rows and running VACUUM FULL (Option D) reduces storage costs, but RDS bills for allocated storage, not used space, so reclaiming space does not lower the bill and VACUUM FULL can cause significant performance disruption.
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
✓
Implement table partitioning and use S3 as an external table for old partitions.
It uses PostgreSQL table partitioning (e.g., range partitioning by date) combined with the `postgres_fdw` or `pg_parquet` extension to treat old partitions as foreign tables stored in Amazon S3. This keeps the hot data in RDS for fast OLTP access while offloading cold data to low-cost S3 storage, minimizing performance impact and reducing storage costs without requiring a full migration or schema redesign.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Move the database to Amazon Aurora PostgreSQL with storage auto-scaling.
Why it's wrong here
Aurora storage is not cheaper than RDS for cold data.
- ✗
Migrate the entire database to Amazon DynamoDB.
Why it's wrong here
Relational schema and joins would be difficult.
- ✓
Implement table partitioning and use S3 as an external table for old partitions.
Why this is correct
Reduces primary storage cost while preserving data access.
- ✗
Delete old rows and run VACUUM FULL to reclaim space.
Why it's wrong here
VACUUM FULL locks tables and is disruptive.
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 |
Go deeper
Related to this question
About these practice questions
This DBS-C01 question is part of Courseiva's 1,663-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-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 DBS-C01 exam.