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Question 1,680 of 1,730

Workload-Specific Database Design →hardMultiple SelectObjective-mapped

Optimizing DynamoDB GSI with Sort Key and Projection for Order Queries

This DBS-C01 practice question tests your understanding of workload-specific database design. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 uses Amazon DynamoDB to store order data. The table has a primary key (OrderID) and a Global Secondary Index (GSI) on CustomerID. The application often queries for all orders of a customer sorted by order date. The GSI projects only the keys. The queries are slow. What should the team do to improve query performance? (Choose two.)

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

A
Enable DynamoDB Accelerator (DAX) for the table
Why wrong: DAX caches data but does not help with sorting or projection issues.
B
Increase the read capacity of the GSI
Why wrong: Increasing read capacity may reduce throttling but does not address the root cause of slow queries.
C
Modify the GSI to include OrderDate as a sort key
Adding OrderDate as a sort key allows the GSI to return items sorted by order date without additional processing.
D
Use a Local Secondary Index (LSI) instead of a GSI
Why wrong: LSI requires the same partition key as the table (OrderID), not CustomerID.
E
Change the GSI projection to include all attributes
Projecting all attributes avoids fetching from the base table, reducing latency.

Full breakdown with real-world context →

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

✓

Modify the GSI to include OrderDate as a sort key

The queries are slow because the GSI projects only keys. When querying the GSI, DynamoDB must fetch the full items from the base table (a 'fetch' operation) for each key, which is inefficient. Option C (modifying the GSI to include OrderDate as a sort key) allows the GSI to sort results by order date natively, improving query performance. Option E (changing the GSI projection to include all attributes) avoids the extra fetch by storing all attributes in the GSI, eliminating the need to access the base table. Option A (DAX) caches results but doesn't solve the sorting or projection issue. Option B (increasing read capacity) doesn't address the inefficiency of key-only projection. Option D (using an LSI) is not possible because LSIs require the same partition key as the base table; CustomerID is different from OrderID, so an LSI cannot be used.

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.

✗
Enable DynamoDB Accelerator (DAX) for the table
Why it's wrong here
DAX caches data but does not help with sorting or projection issues.
✗
Increase the read capacity of the GSI
Why it's wrong here
Increasing read capacity may reduce throttling but does not address the root cause of slow queries.
✓
Modify the GSI to include OrderDate as a sort key
Why this is correct
Adding OrderDate as a sort key allows the GSI to return items sorted by order date without additional processing.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a Local Secondary Index (LSI) instead of a GSI
Why it's wrong here
LSI requires the same partition key as the table (OrderID), not CustomerID.
✓
Change the GSI projection to include all attributes
Why this is correct
Projecting all attributes avoids fetching from the base table, reducing latency.
Clue confirmation
The clue word "primary" 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

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

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 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.

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Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

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FAQ

Questions learners often ask

What does this DBS-C01 question test?

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: Modify the GSI to include OrderDate as a sort key — The queries are slow because the GSI projects only keys. When querying the GSI, DynamoDB must fetch the full items from the base table (a 'fetch' operation) for each key, which is inefficient. Option C (modifying the GSI to include OrderDate as a sort key) allows the GSI to sort results by order date natively, improving query performance. Option E (changing the GSI projection to include all attributes) avoids the extra fetch by storing all attributes in the GSI, eliminating the need to access the base table. Option A (DAX) caches results but doesn't solve the sorting or projection issue. Option B (increasing read capacity) doesn't address the inefficiency of key-only projection. Option D (using an LSI) is not possible because LSIs require the same partition key as the base table; CustomerID is different from OrderID, so an LSI cannot be used.

What should I do if I get this DBS-C01 question wrong?

Are there clue words in this question I should notice?

Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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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.