Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A company uses Azure SQL Database for an employee management system. The Employees table has 10 million rows and a clustered index on EmployeeID (the primary key). Queries that filter employees by Department and then sort by HireDate are very slow. Which indexing strategy will most improve performance for these queries?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
Create a nonclustered index on (Department, HireDate) and include the other needed columns as included columns.
This index supports both the filter (Department) and the sort order (HireDate). Using included columns makes it a covering index for the query, eliminating costly lookups to the clustered index.
B
Distractor review
Create a nonclustered index on (HireDate, Department) with no included columns.
This index would help with sorting by HireDate, but the leading key is HireDate, not Department. To filter by Department efficiently, Department should be the leading key. Also, without included columns, key lookups may still be needed.
C
Distractor review
Create a clustered index on Department.
Changing the clustered index to Department would reorder the entire table physically by Department. While this might speed up departmental queries, it would hurt other queries that rely on the primary key (EmployeeID). A clustered index should generally remain on the primary key for uniqueness and range scans.
D
Distractor review
Drop the existing clustered index and recreate a clustered columnstore index.
Clustered columnstore indexes are designed for large analytical workloads, not for point lookups or queries that sort on a specific column. For transactional queries with filtering and sorting, a traditional B-tree nonclustered index is more appropriate.
Common exam trap
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.
Technical deep dive
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.
Related practice questions
Related DP-900 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
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FAQ
Questions learners often ask
What does this DP-900 question test?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: Create a nonclustered index on (Department, HireDate) and include the other needed columns as included columns. — Creating a nonclustered index on (Department, HireDate) allows the database engine to efficiently locate rows matching the department filter and return them already sorted by HireDate, without needing to scan the entire table or perform a separate sort. Including additional columns as included columns (or making it a covering index) further improves performance by avoiding key lookups.
What should I do if I get this DP-900 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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