Publisher Confirms vs Transactions: Throughput vs Duplicate Handling

Goal

Evaluate the trade‑off between RabbitMQ’s publisher confirms and transaction mode for ensuring message durability while maintaining high throughput.

Constraints & Uncertainty

Testing will be performed locally using the default guest account, which limits us to a single node and excludes remote‑connection scenarios. The behavior of duplicate message delivery when a consumer crashes during a transaction is not fully documented, and broker settings may influence the outcome.

Specific Questions

• When a consumer crashes after acknowledging a message but before a transaction commit, what is the precise duplicate handling behavior in RabbitMQ?
• Which broker configuration options, if any, guarantee that transactions do not produce duplicates under such a crash scenario?
• How does the risk of duplicate messages under publisher confirms compare to that under transactions, especially in high‑throughput workloads?