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Additionally, the broker can include the header, key and value of the original record in the DLQ record, but that takes additional configuration because copying the original record duplicates its content which may be undesirable in performance or security terms. Note that for situations in which the original record is not available when the DLQ record is written, such as log compaction or retention interval having caused removal of the original record, the DLQ record will not contain the original record data.

The broker may batch writing of records onto the DLQ topic for reasons of efficiency. It is possible in rare situations that more than one DLQ record could be written for a particular undeliverable record. This is because the broker does not guarantee to write the DLQ record onto the DLQ topic atomically with the associated write to the internal share-group state topic.

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