Consumer offset.
also: consumer offsets · committed offset · committed offsets · commit the offsetA consumer's position in a stream partition: how far it has read; committing it records progress for restarts.
the two-minute refresher
- Messages stay in the log; the offset says which ones this group has handled.
- Commit AFTER processing: a crash re-delivers (at-least-once), never skips.
- Commit before processing and a crash silently loses messages (at-most-once).
- Resetting the offset backwards replays history, which queues can't do.