Re: Idempotent Producers and Exactly Once Consumers

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Exactly-once on the producer will only ensure that no duplicate writes
happen. If a downstream consumer fails, you might still read message
multiple times for all cases (ie, without idempotence, with idempotence
enabled, or if you use transactions).

Note, that exactly-once is designed for a read-process-write pattern,
but not for a write-read pattern.

-Matthias



On 8/30/19 1:00 PM, Peter Groesbeck wrote:
> For a producer that emits messages to a single topic (i.e. no single
> message is sent to multiple topics), will enabling idempotency but not
> transactions provide exactly once guarantees for downstream consumers of
> said topic?
>
> Ordering is not important I just want to make sure consumers only consumer
> messages sent once.
>