DEA-C01 Data Store Management Practice Question
Network Topology
A data engineer runs the describe-table command shown in the exhibit. The application frequently queries by CustomerID alone. Currently, these queries result in full table scans. Which action should the engineer take to improve query performance?
⚠ Common exam trap
AWS often tests the misconception that increasing capacity (RCUs/WCUs) can fix query performance issues, but the trap here is that throughput and indexing are separate concerns — full table scans are a design problem, not a capacity problem.
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 a global secondary index on CustomerID
The `describe-table` output shows CustomerID is the partition key, but the application frequently queries by CustomerID alone, which currently causes full table scans because there is no index supporting that query pattern. Creating a global secondary index (GSI) on CustomerID allows efficient querying by CustomerID without scanning the entire table, as the GSI provides a separate data structure with its own read/write capacity that can be queried directly.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Change the sort key to OrderID
Why it's wrong here
The sort key alone does not help query on CustomerID.
- ✗
Create a local secondary index on CustomerID
Why it's wrong here
LSI requires the same partition key; not helpful.
- ✗
Increase the read capacity units to 500
Why it's wrong here
More RCUs do not solve the scan issue.
- ✓
Create a global secondary index on CustomerID
Why this is correct
A GSI allows efficient queries on CustomerID.
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Same concept, more angles
1 more way this is tested on DEA-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A data engineer runs this CLI command. Which query is MOST efficient against this table?
hard- ✓ A.Query the CustomerIndex GSI by CustomerID and OrderDate.
- B.Scan the table to find all orders for a CustomerID.
- C.Create a local secondary index on CustomerID.
- D.Query by OrderID and filter by OrderDate.
Why A: The CLI command likely created a global secondary index (GSI) named CustomerIndex on CustomerID and OrderDate. Querying this GSI directly is the most efficient because it uses the index's sort key to retrieve only the relevant items without scanning the entire table, minimizing read capacity consumption.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-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 DEA-C01 exam.