Kafka: __consumer_offsets is a compacted internal topic

Group offsets are stored in Kafka itself, which is why they survive a broker restart.

Code

kafka-console-consumer.sh --bootstrap-server localhost:9092 \
  --topic __consumer_offsets \
  --formatter 'kafka.coordinator.group.GroupMetadataManager$OffsetsMessageFormatter' \
  --from-beginning

Output

[orders-service,orders,0]::OffsetAndMetadata(offset=182034, ...)

Compaction keeps only the latest offset per group and partition.

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Published 2026-08-11