DBS-C01 Workload-Specific Database Design Practice Question
Exhibit
Refer to the exhibit.
```json
{
"MemoryReservation": {
"Value": 500
},
"MemoryUsage": {
"Value": 450
},
"ActiveTransactions": {
"Value": 20
},
"DatabaseConnections": {
"Value": 100
},
"ReadIOPS": {
"Value": 5000
},
"WriteIOPS": {
"Value": 2000
},
"ReadLatency": {
"Value": 2.5
},
"WriteLatency": {
"Value": 5.0
}
}
```
The exhibit shows CloudWatch metrics from an Amazon RDS for PostgreSQL instance (db.r5.large, 16 GB memory, 5000 provisioned IOPS). The application is experiencing slow query performance.Refer to the exhibit. The exhibit shows CloudWatch metrics from an Amazon RDS for PostgreSQL instance. The application is experiencing slow query performance. Which is the most likely cause?
⚠ Common exam trap
The trap here is that candidates see high latency and assume a memory or CPU bottleneck, but the key clue is the IOPS metric hitting its provisioned ceiling, which directly points to storage I/O throttling as the root cause.
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
✓
High storage latency due to provisioned IOPS being fully utilized or EBS volume contention
The exhibit shows that the 'Write IOPS' metric is consistently at or near the provisioned IOPS limit, while 'Write Latency' is elevated. When provisioned IOPS are fully utilized, Amazon EBS throttles I/O, causing increased storage latency. This directly degrades query performance for PostgreSQL, especially for write-heavy workloads, as each write operation must wait for the storage layer to complete.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
High storage latency due to provisioned IOPS being fully utilized or EBS volume contention
Why this is correct
Read/Write latency significantly above expected values for provisioned IOPS storage.
- ✗
High CPU utilization due to complex queries
Why it's wrong here
CPU metrics not shown, but latency is more likely storage-related.
- ✗
Too many database connections causing context switching
Why it's wrong here
100 connections is not excessive for db.r5.large.
- ✗
Insufficient memory causing disk swaps
Why it's wrong here
Memory usage is 450 MB, far below 16 GB.
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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.