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A comment on Kafka is Fast – I'll use Postgres. Parent comment

Re:Kafka is Fast – I'll use Postgres by otterley on Friday October 31, 2025 @06:56PM (#45777623)
What the parent poster described isn’t what makes Kafka’s “exactly once” semantics work. It’s the use of an idempotency token associated with each publication, which effectively turns “at-least-once” semantics into effectively “exactly once” via deduplication.
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Re:Kafka is Fast – I'll use Postgres by saberience on Monday November 03, 2025 @11:38AM (#45800998)
We used Flink and S3 compatible backends (for the Flink state) to ensure exactly once processing.

I didn't say Kafka magically solves these problems for you, but it was required for the scalability we needed.

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