Exam DP-300 topic 4 question 7 discussion

C: is correct.

Azure SQL DB - Query Store is enabled by default, so no need for D. Just save the actual execution plan as .sqlplan, then right click plan in Live Query Statistics -> Compare Showplan, select the saved plan, and SSMS will compare the plans.

Query Store is enabled by default in Azure SQL Database. so C is the correct answer.

I take my last answer (D) back - C is correct

By enabling Query Store, you can retain historical query performance data, including execution plans, which allows you to compare different execution plans over time, including after schema changes like adding an index.

Answer should be D. C does not allow comparing a Live query statistics, only 2 save query plans. D allows you to compare a previous query plan against a plan of a running query. https://learn.microsoft.com/en-us/sql/relational-databases/performance/query-store-usage-scenarios?view=sql-server-ver16

If before adding the index, you have saved the plan, then C is correct answer for sure. But if you didn't save it then need to get it from Query Store. From the context of the question itself, seem to be C is the nearest answer.

C is correct: https://learn.microsoft.com/en-us/sql/relational-databases/performance/compare-execution-plans?view=sql-server-ver16

D. Enable Query Store for DB1. By enabling Query Store for the database, you can compare the previous execution plan to the new one. This feature allows you to view query performance over time, identify regressions, and diagnose issues caused by changes in the execution plan. The Query Store saves the history of queries, execution plans, and runtime statistics, making it easy to compare the actual execution plan before and after the index addition.