Exam Professional Cloud Developer topic 1 question 276 discussion

https://cloud.google.com/pubsub/docs/exactly-once-delivery "This page explains how to receive and acknowledge messages using exactly-once semantics. Only the pull subscription type supports exactly-once delivery, including subscribers that use the StreamingPull API. Push and export subscriptions don't support exactly-once delivery."

Exactly-once delivery is not supported for push subscriptions in Google Cloud Pub/Sub.

pull subscription with both ordering and exactly-once delivery turned off

ordering & pull seems to be the most valid values for downstream service, don't U think ?

In financial services we have to ensure that msg has been consumed ( ACK ) that's for sure, and push is faster, seems that C is the best option

i go for C : push subscription + exactly once delivery so ordering is guaranteed

duplicate from Question #271. IMHO the answer is C. need push, and fast ASAP without spend resource on ordering and so on.

C is correct (I am not a contributor, so unable to vote). Rationale: 1. The downstream application needs only the most up-to-date value for a stock price. There's no need of historical values from a time series, so "ordering" does not make any sense in this scenario. This eliminates alternatives B and D. 2. Next choice is between "push" and "pull". In a "push" subscription, whenever the topic is fed with a new value, it will keep pushing it to the application until an acknowledgement is received. Latency is lower in this case. In a "pull" subscription, there's an additional burden on the application to keep pulling from the topic. This increases latency. A "push" subscription is recommended in such scenarios.

This setup provides the necessary guarantees for message delivery without duplication, and the pull model allows your service to manage message consumption at a pace that ensures the integrity and timeliness of updates in your in-memory database.