KIP-17 — Add HighwaterMarkOffset to OffsetFetchResponse

Discussion ConsumerProtocol

KIP-17 proposes adding the high-watermark offset for each partition to the `OffsetFetchResponse`, enabling consumer lag calculation (HWM − committed offset) in a single RPC without issuing a separate `FetchRequest`. The only existing way to retrieve the HWM is to issue a `FetchRequest` for zero bytes, which is wasteful when no data consumption is intended.

Protocol Impact

Fetch · OffsetFetch

Details