The answer is to choose a larger instance size, create indexes, and use parallel scans to optimize Amazon DocumentDB for aggregation pipelines after migrating from MongoDB. Indexes are critical because $lookup and $group operations rely on efficient data retrieval; without proper indexing, these stages force full collection scans, degrading performance. A larger instance size provides the CPU and memory headroom needed for compute-intensive aggregation stages, while parallel scans distribute the workload across shards or partitions to speed up data processing. On the AWS Certified Database Specialty DBS-C01 exam, this question tests your understanding that DocumentDB’s aggregation engine is not a drop-in replacement for MongoDB’s—common traps include confusing security settings like TLS with performance tuning or disabling journaling, which sacrifices durability. Remember the mnemonic “IPS” for Indexes, Parallel scans, and Size—these three pillars prevent aggregation bottlenecks after migration.
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 company is migrating an on-premises MongoDB workload to Amazon DocumentDB. The workload includes aggregation pipelines with $lookup and $group operations. The team wants to ensure minimal performance impact. Which THREE steps should they take?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create appropriate indexes on fields used in $lookup and $group
Option A (enable TLS) is security, not performance. Option B (create indexes) is critical for $lookup and $group. Option C (increase instance size) helps compute-intensive operations. Option D (disable journaling) is not recommended for durability. Option E (use parallel scans) can speed up aggregations.
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.
✗
Disable journaling to reduce I/O overhead
Why it's wrong here
Disabling journaling risks data loss and is not recommended.
✓
Create appropriate indexes on fields used in $lookup and $group
Read the scenario before looking for a memorised answer.
✗
Enable TLS for all connections
Why it's wrong here
TLS adds overhead but is required for security; not a performance optimization.
✓
Use parallel scan operations where possible
Why this is correct
DocumentDB supports parallel scans to improve throughput.
Related concept
Read the scenario before looking for a memorised answer.
✓
Choose a larger instance size to accommodate the workload
Why this is correct
More memory and CPU help aggregation pipelines.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Identify which DBS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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: Create appropriate indexes on fields used in $lookup and $group — Option A (enable TLS) is security, not performance. Option B (create indexes) is critical for $lookup and $group. Option C (increase instance size) helps compute-intensive operations. Option D (disable journaling) is not recommended for durability. Option E (use parallel scans) can speed up aggregations.
What should I do if I get this DBS-C01 question wrong?
Identify which DBS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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