Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A business analyst needs to query a large Azure SQL Database table that stores sales transactions. The table contains over 100 million rows. The analyst wants to retrieve aggregated sales per product category for the current month. The current query performs a full table scan and takes several minutes. Which indexing strategy will best improve the performance of this aggregation query?
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
Distractor review
Create a clustered index on the transaction date column
A clustered index on date helps with range scans by date but does not efficiently support summing values by category across many rows.
B
Distractor review
Create a nonclustered index on the product category column
A nonclustered index on category helps when filtering by a specific category, but the aggregation needs to scan all categories for the month, still requiring a full scan of the index.
C
Best answer
Create a columnstore index on the table
A columnstore index is purpose-built for analytical queries that aggregate over large tables, using column-wise storage and advanced compression to reduce I/O.
D
Distractor review
Create a filtered index on transactions from the current month
A filtered index on a volatile date range would need to be rebuilt frequently and does not efficiently support aggregation by category across all rows.
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 columnstore index on the table — Columnstore indexes store data column-wise and are highly optimized for analytical queries that perform aggregations over large datasets. They can compress data and scan only the columns needed, resulting in dramatic performance improvements for such workloads. Clustered index on transaction date would help range scans but not aggregations. Nonclustered index on product category would help if the query were filtering by a specific category, but the aggregation still needs to scan all rows for the month. A filtered index would limit the index to the current month's data, which is dynamic and would require rebuilding; it's less practical than a columnstore index for this scenario.
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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