Kafka: Retention deletes by time or size, not by consumption

A record is not removed because it was read; it is removed when the policy says so.

Code

# 7 days (default)
retention.ms=604800000
# or by size per partition
retention.bytes=1073741824

Output

A consumer offline for eight days on a 7-day topic
restarts to OffsetOutOfRangeException and jumps to auto.offset.reset.

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Published 2026-08-11