PubSub: Consuming message fron Subscriber Acknowledged Message using message id

[mmadasamy]

Team,

I consumed message from Pubsub using my subscriber. Can i re consume same message using message id though it's acknowledged.

Thanks,

Samy

[ms4446]

In Google Cloud Pub/Sub, once a message is acknowledged by a subscriber, it is considered successfully processed and is removed from the subscription's queue. This means that you cannot re-consume the same message using its message ID after it has been acknowledged because it is no longer available in the subscription.

If you need to process a message multiple times or by different subscribers, there are a few strategies you can consider:

• Do not immediately acknowledge the message: Instead, process the message and only acknowledge it when you are certain that no further processing is needed. Be mindful that messages must eventually be acknowledged to prevent them from being redelivered indefinitely. If processing or reprocessing fails permanently, a different strategy (like a dead-letter queue) should be used.
• Use a dead-letter queue: Configure your subscription with a dead-letter queue to capture messages that cannot be processed successfully after a certain number of delivery attempts. This allows you to review and reprocess messages as needed.However, this approach is typically used for handling processing failures rather than for re-consuming messages intentionally.
• Publish the message again: If you need to reprocess a message or make it available for consumption by another subscriber, you can publish the message again to the same or a different topic. This effectively creates a new message that can be consumed by subscribers. Be mindful that this approach can lead to message duplication and increased costs, so it should be used judiciously.
• Store messages for reprocessing: Consider storing messages in a database or a cloud storage service if you anticipate the need to reprocess them. This way, you can retrieve and reprocess messages as needed without relying on Pub/Sub's delivery mechanisms.Note that there may be a short delay after the initial message is received before it's available for reprocessing through your storage solution.

Remember, the design of your message processing system should carefully consider the trade-offs between message delivery guarantees (at-least-once, exactly-once, at-most-once) and the complexity of handling message re-consumption or duplication.