The answer is strongly consistent reads, which consume double the read capacity. In DynamoDB, a strongly consistent read uses twice the read capacity units (RCUs) as an eventually consistent read, and with an average item size of 200 KB, each read consumes 200 KB divided by 4 KB, or 50 RCUs. A single request can therefore exhaust a significant portion of the 1000 RCU table capacity, especially under concurrent access, quickly triggering ProvisionedThroughputExceededException. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of how read consistency models impact throughput calculations—a common trap is forgetting that strongly consistent reads round up to the next 4 KB boundary and cost double. Remember the memory tip: “Strong reads cost twice, so size your RCUs nice.”
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. 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 gaming company uses Amazon DynamoDB for player profiles. The access pattern is to retrieve a player's profile by 'player_id'. Each profile includes a list of 'achievements' that can grow up to 400 KB. Recently, the application has been encountering 'ProvisionedThroughputExceededException' errors. The table has 1000 read capacity units (RCU) and 500 write capacity units (WCU). The average item size is 200 KB. What is the MOST likely cause of the throttling?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The application is using strongly consistent reads, which consume double the read capacity.
Strongly consistent reads in DynamoDB consume twice the read capacity units (RCUs) as eventually consistent reads. With an average item size of 200 KB, each strongly consistent read consumes 200 KB / 4 KB = 50 RCUs (rounded up). If the application is using strongly consistent reads, a single read of a 200 KB item uses 50 RCUs, which can quickly exhaust the 1000 RCU table capacity, especially under concurrent access, leading to ProvisionedThroughputExceededException.
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.
✗
The item size exceeds the DynamoDB item size limit of 400 KB.
Why it's wrong here
400 KB is the limit, but the error is throughput, not size.
✗
The read capacity units are set too low for the number of partitions.
Why it's wrong here
RCU is table-level, not per partition.
✗
The partition key 'player_id' is causing hot partitions.
Why it's wrong here
'player_id' is likely evenly distributed.
✓
The application is using strongly consistent reads, which consume double the read capacity.
Why this is correct
Strongly consistent reads consume twice as many RCUs as eventually consistent reads.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may overlook the RCU consumption difference between strongly consistent and eventually consistent reads, assuming all reads consume the same capacity, and instead blame hot partitions or item size limits.
Detailed technical explanation
How to think about this question
DynamoDB charges 1 RCU for one strongly consistent read of up to 4 KB, and 0.5 RCU for one eventually consistent read of up to 4 KB. For a 200 KB item, a strongly consistent read consumes 50 RCUs (200/4), while an eventually consistent read consumes only 25 RCUs. If the application uses strongly consistent reads without need, it doubles the RCU cost per read, making it easy to exceed provisioned capacity under moderate load. In practice, many applications default to eventually consistent reads unless strong consistency is explicitly required, as the latter also adds latency.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The application is using strongly consistent reads, which consume double the read capacity. — Strongly consistent reads in DynamoDB consume twice the read capacity units (RCUs) as eventually consistent reads. With an average item size of 200 KB, each strongly consistent read consumes 200 KB / 4 KB = 50 RCUs (rounded up). If the application is using strongly consistent reads, a single read of a 200 KB item uses 50 RCUs, which can quickly exhaust the 1000 RCU table capacity, especially under concurrent access, leading to ProvisionedThroughputExceededException.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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