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.

C is the correct answer

Given the requirement for maintaining the most up-to-date stock prices in the in-memory database for trading transactions, the suitable setup for the Pub/Sub subscription would be option C: Create a push subscription with exactly-once delivery enabled. This ensures that messages are reliably delivered and processed exactly once, avoiding duplicates and ensuring that the downstream service receives the most recent stock price updates for accurate trading decisions.