Question 400
An app has unstable query latency because the optimizer picks one bad plan for common customer IDs. What should a technical reviewer verify before approving completion?
Explanation
Correct Answer
Query Store keeps plan/runtime history and can help isolate parameter-sensitive plan regressions. The observation “Representative parameter values meet latency targets without breaking atypical cases” directly confirms the chosen action worked for this situation: An app has unstable query latency because the optimizer picks one bad plan for common customer IDs.
Incorrect Answers
Page-level hot spots can constrain concurrency beyond disk capacity; fixes require evidence of actual latch waits. This observation would not establish that the required result occurred for An app has unstable query latency because the optimizer picks one bad plan for common customer IDs. The confirming test is: Representative parameter values meet latency targets without breaking atypical cases.
Stable ordering is essential for pagination; OFFSET without a unique key can duplicate or omit records. This observation would not establish that the required result occurred for An app has unstable query latency because the optimizer picks one bad plan for common customer IDs. The confirming test is: Representative parameter values meet latency targets without breaking atypical cases.
Change triggers and at-least-once deliveries demand explicit deduplication and checkpointing. This observation would not establish that the required result occurred for An app has unstable query latency because the optimizer picks one bad plan for common customer IDs. The confirming test is: Representative parameter values meet latency targets without breaking atypical cases.