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https://issues.apache.org/jira/browse/KAFKA-20035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18060358#comment-18060358
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fujian commented on KAFKA-20035:
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To be honest, I see this more as a bug rather than an issue related to which
{{auto.offset.reset}} strategy should be chosen. Expanding partitions is a
normal operational activity, and regardless of the configured strategy, it
should not result in partial message loss.
In fact, precisely because of this issue, we have had to configure
{{auto.offset.reset}} to {{earliest}} in our production environment. When we
set it to {{{}latest{}}}, our expectation is simply that consumers do not need
to process historical data at startup. We also aware that we may lost some data
if the offset missing (refer to
[KAFKA-19902|https://issues.apache.org/jira/browse/KAFKA-19902]). However, we
certainly do not expect data loss to occur later during normal operations, such
as when partitions are expanded.
For these reasons, I think this issue is still worth addressing and fixing. As
for the specific approach to the fix, that is, of course, a separate discussion.
> Prevent data loss during partition expansion by enforcing "earliest" offset
> reset for dynamically added partitions
> ------------------------------------------------------------------------------------------------------------------
>
> Key: KAFKA-20035
> URL: https://issues.apache.org/jira/browse/KAFKA-20035
> Project: Kafka
> Issue Type: Bug
> Components: clients, consumer, core, group-coordinator
> Reporter: Chia-Ping Tsai
> Assignee: Ken Huang
> Priority: Critical
> Labels: kip
>
> Currently, when a consumer group is configured with {{{}auto.offset.reset =
> latest{}}}, dynamically adding new partitions to a subscribed topic can lead
> to data loss due to a race condition.
> The scenario is as follows:
> # A group subscribes to a topic with {{{}auto.offset.reset = latest{}}}.
> # The topic is expanded (e.g., from 3 to 4 partitions).
> # Producers immediately start writing data to the new partition (Partition
> 3).
> # The Group Coordinator detects the change and assigns Partition 3 to a
> member.
> # The member initializes the partition. Since there is no committed offset,
> it applies the
> # *Result: Any messages written to Partition 3 between step 3 and step 5 are
> skipped and lost.*
> From a user's perspective, {{latest}} should mean "start consuming from the
> point of subscription," not "skip data from newly created infrastructure."
> KIP-1282:
> [https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=406619800]
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