- A
Create a composite B-tree index on (department_id, hire_date)
Composite index on both columns in the filter order can be used for both conditions.
- B
Create a bitmap index on hire_date
Why wrong: Bitmap indexes are for low cardinality; hire_date is high cardinality.
- C
Create a hash index on department_id only
Why wrong: Hash index doesn't support range queries on hire_date.
- D
Create two separate B-tree indexes, one on each column
Why wrong: Separate indexes may not be used together efficiently; the database may use only one index.
Question 452 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 DBA wants to improve query performance on a large table that is frequently filtered on two columns: department_id and hire_date. The table has millions of rows. Which index strategy would be most effective?
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 composite B-tree index on (department_id, hire_date)
A composite B-tree index on (department_id, hire_date) is most effective because it allows the database to satisfy equality and range predicates on both columns in a single index scan. B-tree indexes are optimized for high-cardinality columns and support efficient multi-column filtering when the leading column matches the query's equality condition, followed by the range condition on hire_date.
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.
- ✓
Create a composite B-tree index on (department_id, hire_date)
Why this is correct
Composite index on both columns in the filter order can be used for both conditions.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a bitmap index on hire_date
Why it's wrong here
Bitmap indexes are for low cardinality; hire_date is high cardinality.
- ✗
Create a hash index on department_id only
Why it's wrong here
Hash index doesn't support range queries on hire_date.
- ✗
Create two separate B-tree indexes, one on each column
Why it's wrong here
Separate indexes may not be used together efficiently; the database may use only one index.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume two separate single-column indexes are equivalent to a composite index, but they fail to realize that the database cannot efficiently combine them for range predicates without a costly index merge operation.
Detailed technical explanation
How to think about this question
Under the hood, a composite B-tree index stores entries sorted by the first column, then by the second column within ties, enabling the database to perform a single index range scan for queries like WHERE department_id = 10 AND hire_date BETWEEN '2020-01-01' AND '2020-12-31'. In real-world scenarios, this strategy is critical for large fact tables in data warehouses where queries frequently filter on a dimension key and a date range, as it avoids costly full table scans and reduces I/O by leveraging index-only scans if all needed columns are included.
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.
- →
Data Concepts and Environments — study guide chapter
Learn the concepts, then practise the questions
- →
Data Concepts and Environments practice questions
Targeted practice on this topic area only
- →
All DA0-001 questions
1,000 questions across all exam domains
- →
CompTIA Data+ DA0-001 study guide
Full concept coverage aligned to exam objectives
- →
DA0-001 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related DA0-001 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Data Concepts and Environments practice questions
Practise DA0-001 questions linked to Data Concepts and Environments.
Analysing Data practice questions
Practise DA0-001 questions linked to Analysing Data.
Visualising Data practice questions
Practise DA0-001 questions linked to Visualising Data.
Reporting Insights practice questions
Practise DA0-001 questions linked to Reporting Insights.
Mining Data practice questions
Practise DA0-001 questions linked to Mining Data.
Comparing and Contrasting Data Concepts practice questions
Practise DA0-001 questions linked to Comparing and Contrasting Data Concepts.
Mining and Acquiring Data practice questions
Practise DA0-001 questions linked to Mining and Acquiring Data.
Analyzing and Modeling Data practice questions
Practise DA0-001 questions linked to Analyzing and Modeling Data.
Visualizing Data practice questions
Practise DA0-001 questions linked to Visualizing Data.
Communicating Data Insights practice questions
Practise DA0-001 questions linked to Communicating Data Insights.
CompTIA A+ hardware practice questions
Practise DA0-001 questions linked to CompTIA A+ hardware.
CompTIA A+ mobile devices practice questions
Practise DA0-001 questions linked to CompTIA A+ mobile devices.
Practice this exam
Start a free DA0-001 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
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: Create a composite B-tree index on (department_id, hire_date) — A composite B-tree index on (department_id, hire_date) is most effective because it allows the database to satisfy equality and range predicates on both columns in a single index scan. B-tree indexes are optimized for high-cardinality columns and support efficient multi-column filtering when the leading column matches the query's equality condition, followed by the range condition on hire_date.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.