EventHubs

Azure Event Hubs guarantees only at-least-once delivery, meaning the same event can occasionally be redelivered by design. EventHubs Log Collector now suppresses these redeliveries within certain bounds, but duplication can still occur outside those bounds:

• Deduplication window: Duplicate logs are suppressed only if the repeat is received within 4 hours of the original. A repeat arriving after 4 hours will be ingested as a new, separate event.

• Checksum store limit: The deduplication store retains the last 20,000 logs. If a log reappears after its record has been evicted from this store, it will be treated as new and ingested again.

• One-time repeat after upgrade: Logs seen prior to upgrading to this version may appear once more after the upgrade. This single repeat is expected and does not indicate a recurrence of the issue.