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Matthias J. Sax commented on KAFKA-14747: ----------------------------------------- Sure. Not sure if we need a KIP or not. [~guozhang] WDYT? > FK join should record discarded subscription responses > ------------------------------------------------------ > > Key: KAFKA-14747 > URL: https://issues.apache.org/jira/browse/KAFKA-14747 > Project: Kafka > Issue Type: Improvement > Components: streams > Reporter: Matthias J. Sax > Assignee: Koma Zhang > Priority: Minor > Labels: beginner, needs-kip, newbie > > FK-joins are subject to a race condition: If the left-hand side record is > updated, a subscription is sent to the right-hand side (including a hash > value of the left-hand side record), and the right-hand side might send back > join responses (also including the original hash). The left-hand side only > processed the responses if the returned hash matches to current hash of the > left-hand side record, because a different hash implies that the lef- hand > side record was updated in the mean time (including sending a new > subscription to the right hand side), and thus the data is stale and the > response should not be processed (joining the response to the new record > could lead to incorrect results). > A similar thing can happen on a right-hand side update that triggers a > response, that might be dropped if the left-hand side record was updated in > parallel. > While the behavior is correct, we don't record if this happens. We should > consider to record this using the existing "dropped record" sensor or maybe > add a new sensor. -- This message was sent by Atlassian Jira (v8.20.10#820010)