Exam DP-420 topic 3 question 2 discussion

After processing items in the change feed, you can build a materialized view and persist aggregated values back in Azure Cosmos DB. If you're using Azure Cosmos DB to build a game, you can, for example, use change feed to implement real-time leaderboards based on scores from completed games. https://docs.microsoft.com/en-us/azure/cosmos-db/sql/change-feed-design-patterns#high-availability

For most scenarios, using the change feed to populate aggregates in Cosmos DB is the more RU-efficient approach. It allows you to process changes incrementally, update aggregates in real-time, and avoid the overhead of full scans. However, consider your specific data volume, change frequency, and aggregate complexity to choose the most appropriate strategy.

B is correct, no additional SQL queries necessary

The answer is D

Selected Answer: B

Option D suggests populating the aggregates by using SQL queries that run daily. While this may reduce the RU consumption during querying, it may not necessarily minimize RU consumption overall. Additionally, this approach may result in stale data since the aggregates are only updated once a day. The best approach to minimize RU consumption and ensure the report runs as quickly as possible is to use the change feed to populate the aggregates in real-time, as suggested in option B. This way, the aggregates are always up-to-date, and the report can be generated quickly and with minimal RU consumption.

B Is Correct

I would go with D, we need to minimize RU, so we run the job daily which should be fine for these types of reports (using monthly data). Using the change feed costs much more RU.

B Is Correct

I would go with D, as we need to reduce RU. An additional container writes costs RU and the change-feed will be updated every time a new item appears.