DBS-C01 Workload-Specific Database Design Practice Question
A company runs an online transaction processing (OLTP) workload on Amazon RDS for PostgreSQL. The database has grown to 2 TB and the company needs to run complex analytical queries that join multiple large tables. These analytical queries are slowing down the OLTP operations. What is the MOST cost-effective solution to separate the workloads?
⚠ Common exam trap
Watch out — candidates often choose Redshift (Option C) assuming it is always the best for analytics, but the question asks for the most cost-effective solution, and a read replica avoids the cost and complexity of a full data warehouse migration while still separating workloads.
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 RDS for PostgreSQL read replica and route analytical queries to it.
Creating an RDS for PostgreSQL read replica is the most cost-effective solution because it offloads analytical queries to a separate read-only instance without requiring a full database migration. The read replica uses PostgreSQL's native streaming replication to maintain near-real-time data consistency, allowing complex joins on large tables without competing for the primary instance's I/O and CPU resources. This approach minimizes operational overhead and cost compared to migrating to a separate analytics platform like Redshift.
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 an RDS for PostgreSQL read replica and route analytical queries to it.
Why this is correct
Read replica offloads read-only queries, cost-effective.
- ✗
Use Amazon ElastiCache for caching analytical query results.
Why it's wrong here
Caching does not solve the problem of heavy analytical queries impacting OLTP.
- ✗
Migrate the analytical queries to Amazon Redshift.
Why it's wrong here
Overkill and more expensive for this workload.
- ✗
Migrate the OLTP workload to Amazon DynamoDB.
Why it's wrong here
DynamoDB does not support complex joins.
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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.