An executive dashboard reruns the same aggregation query every few minutes against an unchanging daily table. The dashboard must respond in under a second when people interact with it. Which approach fits best?
Show answer and explanation
Answer: D
BigQuery stores results of identical queries for about 24 hours at no query cost, so repeated dashboard refreshes can be served from cache while the underlying tables are unchanged. For interactive dashboards that need sub-second response, BI Engine adds an in-memory acceleration layer over frequently used tables. Turning off caching adds cost and latency, Memorystore is not built for analytical SQL over warehouse data, and exporting to Cloud SQL adds a copy that must be maintained.
Why the other options are wrong
- A. Disabling the result cache forces every refresh to read and bill for the full scan again. That raises cost and latency, the opposite of what the dashboard needs.
- B. Memorystore is a key-value cache for application data. It would need a separate pipeline to keep aggregates fresh and it does not run BigQuery SQL.
- C. Copying data into Cloud SQL before every refresh adds export time and a second system to maintain, and Cloud SQL is not designed for warehouse-scale aggregation.
Exam tip. Identical queries hit the free result cache; BI Engine is the answer when a dashboard needs interactive, sub-second speed.