DP-300 Practice Question: Monitor, configure, and optimize database resources
Which TWO options are valid methods to optimize query performance in Azure SQL Managed Instance?
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
✓
Use columnstore indexes on large tables
Options A and D are correct. Columnstore indexes (A) improve analytical query performance by reducing I/O and using batch processing. Query Store (D) helps identify regressions by tracking execution plans and performance metrics. Option B is incorrect; setting database compatibility level to 150 may enable new features but is not a direct query optimization method. Option C is incorrect; increasing storage size does not improve query performance. Option E is incorrect; Transparent Data Encryption (TDE) secures data but does not enhance performance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use columnstore indexes on large tables
Why this is correct
Columnstore indexes store data column-wise with compression and batch-mode execution, cutting I/O for large analytical scans on Azure SQL Managed Instance. This directly satisfies the stem's query performance optimisation goal for large tables, where rowstore indexes would scan far more pages.
- ✗
Set database compatibility level to 150
Why it's wrong here
Compatibility level 150 governs parser and cardinality-estimator behaviour, not index or statistics quality, so it cannot fix a poorly tuned query on its own. It tempts because higher levels unlock Intelligent Query Processing features. Raising the level is correct when the workload needs those newer optimiser capabilities and the application has been tested against them.
- ✗
Increase the maximum storage size
Why it's wrong here
Maximum storage size sets the data-file ceiling; it changes neither the query plan nor index availability, so it cannot improve query speed. It tempts because storage limits feel like a performance lever. Increasing it is correct when the database is approaching its size cap and needs room to grow, not when queries are slow.
- ✓
Enable Query Store and monitor regressions
Why this is correct
Query Store captures execution plans, runtime statistics and wait categories per query, exposing regressions after statistics, index or compatibility changes. This directly satisfies the stem's optimisation requirement by identifying which queries degraded and why, enabling targeted tuning rather than guesswork across the instance.
- ✗
Enable Transparent Data Encryption (TDE)
Why it's wrong here
TDE encrypts data and log files at rest; it adds no indexes, statistics or plan improvements, so query execution is unaffected. It tempts because encryption is a common database hardening task. Enabling TDE is correct when the requirement is regulatory at-rest protection for the managed instance's files.
Go deeper
Related to this question
Learn chapter
Deploying and Configuring Azure SQL Managed Instance
Key term
Azure SQL Managed Instance
Azure SQL Managed Instance is a fully managed cloud database service that gives you nearly all the features of Microsoft SQL Server on your own server, without you having to manage the hardware or operating system.
Key term
Transparent Data Encryption
Transparent Data Encryption is a security feature that automatically encrypts data written to a database and decrypts it when read, without requiring any changes to the application.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DP-300 practice question is part of Courseiva's free Microsoft 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 DP-300 exam.