DP-300 Practice Question: Monitor, configure, and optimize database resources
You manage an Azure SQL Database that runs a reporting workload. Users report that queries are slow only when they filter on a specific customer region, and the slowness began after a large data load. You run Query Store and identify a plan that regressed. You want the database engine to automatically detect and revert to the last known good plan for that query. What should you configure?
⚠ Common exam trap
Test-takers frequently confuse automatic tuning features that create objects (like indexes) with those that correct existing plan regressions.
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
✓
Enable automatic tuning with the FORCE_LAST_GOOD_PLAN option.
Automatic tuning with FORCE_LAST_GOOD_PLAN is the correct choice because it directly addresses plan regression by automatically reverting to a previously good plan when performance degrades. The other options either collect data without acting, create indexes, or change compatibility levels, none of which provide the automatic regression correction required.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Enable automatic tuning with the CREATE_INDEX option.
Why it's wrong here
CREATE_INDEX automatically creates missing indexes based on workload analysis; it does not detect plan regressions or revert to previous plans. While it can improve performance, it addresses a different root cause (missing indexes) rather than a regression caused by a plan change.
- ✗
Set the database compatibility level to the latest version.
Why it's wrong here
Changing the compatibility level affects query optimizer behaviors and may introduce plan changes, but it does not automatically detect or revert plan regressions. It is a manual, broad change that could worsen performance if the regression was caused by the new compatibility level.
- ✓
Enable automatic tuning with the FORCE_LAST_GOOD_PLAN option.
Why this is correct
FORCE_LAST_GOOD_PLAN is an automatic tuning feature in Azure SQL Database that monitors for plan regressions and automatically forces the last known good plan when a regression is detected. It is specifically designed for the scenario where a query becomes slower due to a plan change, which matches the reported symptom.
- ✗
Configure Query Store to use AUTO plan capture mode.
Why it's wrong here
AUTO plan capture mode in Query Store records plans automatically, but it only collects diagnostic data; it does not take corrective action such as forcing a previous plan. It is a monitoring setting, not an automatic tuning feature.
Go deeper
Related to this question
Learn chapter
Optimizing Database Query and Index Performance
Key term
Azure SQL Performance Tuning
Azure SQL Performance Tuning is the process of optimizing the speed and efficiency of queries and database operations in Microsoft Azure SQL Database or SQL Managed Instance to reduce latency and improve throughput.
Key term
Query Store
Query Store is a built-in SQL Server feature that captures and stores a history of query execution plans and performance data for easy monitoring and troubleshooting.
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Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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