- A
Key-value store; create a secondary index on category
Why wrong: Key-value stores typically index only by key; secondary indexes are not common.
- B
Graph database; create a relationship between products
Why wrong: Graph databases are for connected data, not document storage.
- C
Document database; create an index on category
Document databases support secondary indexes on any field, which speeds up queries.
- D
Wide-column store; create a column family for category
Why wrong: Wide-column stores are different from document databases; the scenario describes documents.
Question 59 of 1,000
DA0-001 Data Concepts and Environments Practice Question
This DA0-001 practice question tests your understanding of data concepts and environments. 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 uses a NoSQL document database to store product catalogs. Each product document includes fields like product_id, name, category, and price. The operations team frequently queries by product_id and by category. Which type of NoSQL database is being used, and what should be created to optimize queries by category?
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
✓
Document database; create an index on category
The question explicitly states a document database is used, and the operations team frequently queries by category. In a document database like MongoDB, creating an index on the category field optimizes these queries by allowing the database to quickly locate documents without scanning every document in the collection. This is the standard approach for improving query performance on non-primary-key fields in document stores.
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.
- ✗
Key-value store; create a secondary index on category
Why it's wrong here
Key-value stores typically index only by key; secondary indexes are not common.
- ✗
Graph database; create a relationship between products
Why it's wrong here
Graph databases are for connected data, not document storage.
- ✓
Document database; create an index on category
Why this is correct
Document databases support secondary indexes on any field, which speeds up queries.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Wide-column store; create a column family for category
Why it's wrong here
Wide-column stores are different from document databases; the scenario describes documents.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA Data+ may test the misconception that all NoSQL databases support secondary indexes similarly. The trap here is that document databases natively support secondary indexes, while key-value and wide-column stores require different optimization strategies.
Trap categories for this question
Scenario analysis trap
Wide-column stores are different from document databases; the scenario describes documents.
Detailed technical explanation
How to think about this question
Under the hood, a document database like MongoDB uses B-tree indexes on fields such as category, which store sorted references to documents for efficient range and equality queries. A subtle behavior is that compound indexes (e.g., on category and price) can further optimize queries that filter by both fields, but a single-field index on category is sufficient for the described use case. In a real-world scenario, without this index, a query for all products in 'Electronics' would trigger a full collection scan, degrading performance as the catalog grows to millions of documents.
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 practitioner preparing for the DA0-001 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
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FAQ
Questions learners often ask
What does this DA0-001 question test?
Data Concepts and Environments — This question tests Data Concepts and Environments — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Document database; create an index on category — The question explicitly states a document database is used, and the operations team frequently queries by category. In a document database like MongoDB, creating an index on the category field optimizes these queries by allowing the database to quickly locate documents without scanning every document in the collection. This is the standard approach for improving query performance on non-primary-key fields in document stores.
What should I do if I get this DA0-001 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This DA0-001 practice question is part of Courseiva's free CompTIA 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 DA0-001 exam.
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