Question 903 of 982

Identify considerations for relational data on Azure →mediumMultiple ChoiceObjective-mapped

DP-900 Practice Question: Identify considerations for relational data on Azure

This DP-900 practice question tests your understanding of identify considerations for relational data on azure. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 Azure SQL Database for an HR system. The Employees table has a clustered index on EmployeeID. Queries frequently filter on DepartmentID and LastName and also retrieve the Salary column. The table contains over a million rows. Which index strategy will most improve query performance for these filters?

Question 1mediummultiple choice

Full question →

A
A: Create a nonclustered index on (DepartmentID, LastName) INCLUDE (Salary)
This composite covering index includes all columns needed for the query, avoiding expensive key lookups into the clustered index.
B
B: Create a nonclustered index on LastName only
Why wrong: An index on LastName alone does not cover the DepartmentID filter, so the database would still need to scan or lookup rows, which is less efficient.
C
C: Create a nonclustered index on DepartmentID and another nonclustered index on LastName
Why wrong: Separate indexes could lead to index intersection, but this is less efficient than a single composite index and still may require key lookups for Salary.
D
D: Change the clustered index to (DepartmentID, LastName)
Why wrong: Changing the clustered index would alter the physical order of the table and could negatively affect other queries that rely on EmployeeID ordering, and it does not cover Salary.

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

✓

A: Create a nonclustered index on (DepartmentID, LastName) INCLUDE (Salary)

Option A is correct because it creates a covering nonclustered index on the filter columns (DepartmentID, LastName) and includes the Salary column as an included column. This allows the query to be fully satisfied by scanning only the nonclustered index pages, avoiding key lookups to the clustered index. The order of columns in the index key matches the query filter pattern, maximizing seek efficiency.

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.

✓
A: Create a nonclustered index on (DepartmentID, LastName) INCLUDE (Salary)
Why this is correct
This composite covering index includes all columns needed for the query, avoiding expensive key lookups into the clustered index.
Related concept
Read the scenario before looking for a memorised answer.
✗
B: Create a nonclustered index on LastName only
Why it's wrong here
An index on LastName alone does not cover the DepartmentID filter, so the database would still need to scan or lookup rows, which is less efficient.
✗
C: Create a nonclustered index on DepartmentID and another nonclustered index on LastName
Why it's wrong here
Separate indexes could lead to index intersection, but this is less efficient than a single composite index and still may require key lookups for Salary.
✗
D: Change the clustered index to (DepartmentID, LastName)
Why it's wrong here
Changing the clustered index would alter the physical order of the table and could negatively affect other queries that rely on EmployeeID ordering, and it does not cover Salary.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often think separate single-column indexes are sufficient for multi-column filters, but they overlook the need for a covering composite index to avoid expensive key lookups or index intersection operations.

Detailed technical explanation

How to think about this question

In Azure SQL Database, a nonclustered index with included columns stores the key columns in a B-tree structure for fast seek, while included columns are stored only at the leaf level. This design avoids adding the Salary column to the index key, which would increase index size and slow down inserts/updates. The composite index on (DepartmentID, LastName) leverages the leftmost prefix rule, so queries filtering on DepartmentID alone or both columns can use the index efficiently.

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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.

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 DP-900 question test?

Identify considerations for relational data on Azure — This question tests Identify considerations for relational data on Azure — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: A: Create a nonclustered index on (DepartmentID, LastName) INCLUDE (Salary) — Option A is correct because it creates a covering nonclustered index on the filter columns (DepartmentID, LastName) and includes the Salary column as an included column. This allows the query to be fully satisfied by scanning only the nonclustered index pages, avoiding key lookups to the clustered index. The order of columns in the index key matches the query filter pattern, maximizing seek efficiency.

What should I do if I get this DP-900 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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