Hi, Chia-Ping, One potential downside of changing the default is that some existing tools (e.g. console consumer) may depend on this behavior. For example, a user testing the system may expect to see only new messages and could be surprised by the change. Another option is to leave the default unchanged, but document clearly how to prevent losing messages on new partitions through by_duration. The users can then make the corresponding config changes if needed.
Thanks, Jun On Wed, Jul 1, 2026 at 9:39 AM Chia-Ping Tsai <[email protected]> wrote: > Hi Jun, > > Thanks for the feedback. I agree with your conclusion. It would be better > to "make haste" with a new KIP to address this. We can focus the discussion > on the following points: > > 1) Should we change the default reset policy to by_duration for all > consumers? > 2) What is the optimal duration to prevent data loss while avoiding large > backlogs? Note that the classic consumer has a 3-second heartbeat interval, > whereas the async consumer uses 5 seconds. > 3) What are the potential side effects of replacing latest with > by_duration as the default behavior? > > Best, > Chia-Ping > > On 2026/06/30 20:39:24 Jun Rao via dev wrote: > > Hi, Chia-Ping, > > > > I agree that using by_duration with a value of 5s to 10s addresses most > > common issues with expanded partitions, given the default > > heartbeat.interval.ms is 3 seconds. We can consider setting that as the > new > > default. The current proposal may address some other rarer cases, but it > > feels a bit like over engineering. > > > > Thanks, > > > > Jun > > > > On Tue, Jun 30, 2026 at 5:58 AM Chia-Ping Tsai <[email protected]> > wrote: > > > > > - Short durations fail during extended downtimes, leading to the exact > > > silent data > > > loss this KIP aims to prevent. > > > > > > Losing the records produced to expanded partitions during a downtime is > > > actually the expected behavior for the latest policy. This is exactly > why, > > > in the current KIP proposal, we prefer by_duration over earliest for > the > > > expanded partitions—we want to avoid forcing users to consume a massive > > > accumulated backlog just because a partition is technically "new". > > > > > > To quote my previous comment from May 15: > > > "...if a consumer is offline for a while and a new partition is created > > > during that downtime, the user might actually want to skip to latest > when > > > resuming, rather than reading from earliest just because the partition > is > > > technically 'new' to the group." > > > > > > On 2026/06/30 12:12:47 黃竣陽 wrote: > > > > Hello all, > > > > > > > > The metadata blindness and consumer downtime windows are inherently > > > > unpredictable, making a fixed by_duration approach unviable. No > static > > > > duration can accommodate both extremes: > > > > > > > > - Short durations fail during extended downtimes, leading to the > exact > > > silent data > > > > loss this KIP aims to prevent. > > > > - Long durations (calibrated for worst-case scenarios) cause routine > > > restarts to > > > > trigger unnecessary mass replays, undermining the latest offset reset > > > policy. > > > > > > > > This is why the proposed solution uses creation time. It provides a > > > discrete, > > > > deterministic signal—verifying whether a partition is actually newer > > > than the group, > > > > rather than relying on an arbitrary time window that has no > correlation > > > with the consumer’s > > > > actual downtime. > > > > > > > > Best Regards, > > > > Jiunn-Yang > > > > > > > > > Chia-Ping Tsai <[email protected]> 於 2026年6月30日 下午3:05 寫道： > > > > > > > > > > Hi all, > > > > > > > > > > I'd like to revisit Jun previous comment about using > by_duration=5s. I > > > realize now that having a small backlog is actually an acceptable > > > trade-off, especially since the latest policy inherently brings a tiny > > > backlog to starting consumers anyway due to the time gap between > fetching > > > the offset and actually consuming. > > > > > > > > > > If we bring the simple by_duration=5s solution back to the KIP, I'd > > > like to discuss a further step: Should we just change the default > policy > > > from latest to by_duration=5s specifically for the new consumer and > share > > > consumer? > > > > > > > > > > Best, > > > > > Chia-Ping > > > > > > > > > > On 2026/06/15 17:39:19 Chia-Ping Tsai wrote: > > > > >> hi Jun > > > > >> > > > > >> The most important part of this story is how users should expect > the > > > data > > > > >> they can see when using the latest or by_duration policy with > expanded > > > > >> partitions. > > > > >> > > > > >> Yes, the by_duration policy can minimize data loss, but it is > > > > >> non-deterministic, which means users will either read too many > > > historical > > > > >> records from existing partitions or lose some records from > expanded > > > > >> partitions. > > > > >> > > > > >> Also, I agree that auto.offset.reset.max.age.ms is a bit hard to > > > > >> understand, and that is why I preferred having a whole new policy > > > based > > > > >> entirely on group creation time (KIP-1282) > > > > >> > > > > >> Best, > > > > >> Chia-Ping > > > > >> > > > > >> Jun Rao via dev <[email protected]> 於 2026年6月16日週二 上午1:08寫道： > > > > >> > > > > >>> Hi, Chia-Ping and Jiunn-Yang, > > > > >>> > > > > >>> Thanks for the reply. I am still trying to understand the value > of > > > the new > > > > >>> configs with the KIP. > > > > >>> > > > > >>> The motivation of the KIP is that a user doesn't want to miss the > > > data if > > > > >>> the backlog is small. The backlog of the existing partition is > easy > > > to > > > > >>> understand because it relates to retention time. The backlog for > the > > > new > > > > >>> partition is a bit subtle to understand since it depends on the > > > metadata > > > > >>> refresh delay. To set auto.offset.reset.max.age.ms, the user > needs > > > to > > > > >>> understand the metadata refresh delay on the consumer side and > use > > > it to > > > > >>> set the config. > > > > >>> > > > > >>> Now, let's consider the alternative: setting the same value for > the > > > > >>> existing by_duration policy. The KIP lists three issues with this > > > approach. > > > > >>> 1. It computes the seek target client-side as now() - duration, > which > > > > >>> introduces clock skew across consumers and forces operators to > choose > > > > >>> overly large durations, causing unnecessary reprocessing. > > > > >>> 2. The target timestamp is recomputed on each retry, so failed > > > > >>> ListOffsetsRequest retries can shift the target forward and > > > potentially > > > > >>> miss records produced between attempts. > > > > >>> 3. It applies uniformly to all partitions without committed > offsets, > > > and > > > > >>> cannot distinguish newly expanded partitions from long-existing > > > partitions > > > > >>> newly assigned to the group, leading to unnecessary replay. > > > > >>> > > > > >>> Issues 1 and 2 are uncommon and can be mitigated by adding a bit > > > buffer to > > > > >>> the metadata refresh delay. We could also consider improving the > > > > >>> implementation. For issue 3, the metadata refresh delay is > typically > > > low > > > > >>> (in the order of minutes with the classic consumer and tens of > > > seconds with > > > > >>> the new consumer). If a user is ok with reading that much backlog > > > for new > > > > >>> partitions, it seems they will be ok doing the same for existing > > > > >>> partitions. > > > > >>> > > > > >>> So, instead of introducing a new config, could we just reuse the > > > existing > > > > >>> config with better documentation and/or implementation? > > > > >>> > > > > >>> Jun > > > > >>> > > > > >>> > > > > >>> On Sat, Jun 13, 2026 at 12:19 AM 黃竣陽 <[email protected]> wrote: > > > > >>> > > > > >>>> Hello Jun, > > > > >>>> > > > > >>>> You're right that group creation time is the more intuitive > answer > > > at > > > > >>>> first glance, > > > > >>>> the KIP's own motivation talks about partitions that "predate > the > > > group" > > > > >>>> vs partitions > > > > >>>> "created during group runtime," which directly points to a > > > > >>> group-lifecycle > > > > >>>> classifier. > > > > >>>> I'd like to walk through why we landed on partition age, and the > > > > >>>> trade-offs we considered. > > > > >>>> > > > > >>>> We evaluated three candidate signals: > > > > >>>> > > > > >>>> 1. `by_duration:5secs` > > > > >>>> > > > > >>>> This covers the metadata blindness window, but has issues the > KIP > > > > >>>> currently documents > > > > >>>> under "Why not use `by_duration`?": > > > > >>>> > > > > >>>> - Client-side `now() - duration` introduces clock skew across > > > consumers. > > > > >>>> - `ListOffsets` retries shift the target forward, potentially > > > missing > > > > >>>> records produced between > > > > >>>> attempts. > > > > >>>> - It applies uniformly to all partitions without committed > offsets, > > > > >>>> including pre-existing partitions > > > > >>>> newly assigned to the group, causing unnecessary replay. > > > > >>>> > > > > >>>> 2. Group creation time as classifier > > > > >>>> > > > > >>>> This works cleanly when the consumer is actively running. Our > > > concern > > > > >>>> is the idle / late-rejoin case: > > > > >>>> > > > > >>>> T=0: Group created. > > > > >>>> T=1..T=100: Consumer idle (down, disconnected, etc.). > > > > >>>> T=50: Partition added during the idle window. > > > > >>>> T=100: Consumer resumes. > > > > >>>> > > > > >>>> Under group creation time, the new partition is classified as > new > > > > >>>> (`50 > 0`) and reset to `earliest`, replaying everything from > T=50. > > > > >>>> But during `[T=1, T=100]`, base partitions also accumulated data > > > that > > > > >>>> the consumer accepts as lost — that is precisely the contract of > > > > >>>> `auto.offset.reset=latest`. There is no principled reason to > treat > > > > >>>> the new partition differently; both contain backlog accumulated > > > during > > > > >>>> the same idle window. > > > > >>>> > > > > >>>> This aligns with the "backlog is backlog” principle you raised > in > > > > >>>> the KIP-1282 thread: a `latest` user has tolerated some backlog > on > > > > >>>> every other partition during the same idle period; forcing > 0-backlog > > > > >>>> tolerance only on new partitions would be inconsistent with that > > > > >>>> tolerance. > > > > >>>> > > > > >>>> 3. Partition age vs threshold > > > > >>>> > > > > >>>> Partition age corresponds to the actual silent data loss window, > > > > >>>> the gap between partition creation and the consumer’s metadata > > > > >>>> refresh. Within this window, data loss is genuinely silent: the > > > > >>>> consumer had no opportunity to know about the partition. Outside > > > this > > > > >>>> window, missing data reflects either: > > > > >>>> > > > > >>>> - (a) the user’s tolerated cost of running with idle consumers, > or > > > > >>>> - (b) an operational issue to surface via monitoring, not via > reset > > > > >>> policy. > > > > >>>> > > > > >>>> We did not choose partition age because it is more elegant than > > > group > > > > >>>> creation time — we chose it because its failure mode (requires a > > > > >>>> threshold) is > > > > >>>> less invasive than the failure mode of group creation time > > > (overrides > > > > >>>> user-stated > > > > >>>> `latest` intent during idle periods). > > > > >>>> > > > > >>>> Best Regards, > > > > >>>> Jiunn-Yang > > > > >>>> > > > > >>>>> Chia-Ping Tsai <[email protected]> 於 2026年6月13日 上午11:52 寫道： > > > > >>>>> > > > > >>>>> Hi Jun, > > > > >>>>> > > > > >>>>> Relying on both creation times will create an inconsistent > > > scenario. A > > > > >>>>> consumer that lost all offsets due to a long sleep will seek > to the > > > > >>>>> beginning for the partitions created later than the group. > > > > >>>>> > > > > >>>>> That is why we initially proposed KIP-1282 to fix the > inconsistency > > > > >>>> using a > > > > >>>>> whole new policy. Since KIP-1282 couldn't reach a consensus, > > > KIP-1327 > > > > >>>> goes > > > > >>>>> back to using flexible configurations to prevent users from > falling > > > > >>> into > > > > >>>>> that pitfall. > > > > >>>>> > > > > >>>>> Best, Chia-Ping > > > > >>>>> > > > > >>>>> Jun Rao via dev <[email protected]> 於 2026年6月13日週六 > 上午6:49寫道： > > > > >>>>> > > > > >>>>>> Hi, Jiunn-Yang, > > > > >>>>>> > > > > >>>>>> Thanks for the reply and sorry for the late reply. > > > > >>>>>> > > > > >>>>>> JR1. The design of auto.offset.reset.max.age.ms still feels > > > weird to > > > > >>>> me. > > > > >>>>>> It > > > > >>>>>> categorizes partitions as new or existing based on the > partition > > > > >>>> creation > > > > >>>>>> time. Intuitively, the categorization should be based on the > group > > > > >>>> creation > > > > >>>>>> time: all partitions existing when the group is created are > > > existing > > > > >>> and > > > > >>>>>> all partitions created after the group creation are new > > > partitions. > > > > >>>>>> > > > > >>>>>> Jun > > > > >>>>>> > > > > >>>>>> > > > > >>>>>> > > > > >>>>>> On Tue, Jun 9, 2026 at 8:51 AM 黃竣陽 <[email protected]> > wrote: > > > > >>>>>> > > > > >>>>>>> Hi all, > > > > >>>>>>> > > > > >>>>>>> Manually bumping this thread. If there is no further > > > > >>>>>>> discussion, I will close the vote. > > > > >>>>>>> > > > > >>>>>>> Best Regards, > > > > >>>>>>> Jiunn-Yang > > > > >>>>>>> > > > > >>>>>>>> 黃竣陽 <[email protected]> 於 2026年6月1日 晚上7:16 寫道： > > > > >>>>>>>> > > > > >>>>>>>> Hello Jian, > > > > >>>>>>>> > > > > >>>>>>>> Thanks for your feedback, > > > > >>>>>>>> > > > > >>>>>>>> Agreed, partition expansion is a common operational task, > not an > > > > >>> edge > > > > >>>>>>>> case. I've updated the Motivation section accordingly. > > > > >>>>>>>> > > > > >>>>>>>> Best Regards, > > > > >>>>>>>> Jiunn-Yang > > > > >>>>>>>> > > > > >>>>>>>>> jian fu <[email protected]> 於 2026年6月1日 下午5:49 寫道： > > > > >>>>>>>>> > > > > >>>>>>>>> Hi Jiunn-Yang: > > > > >>>>>>>>> > > > > >>>>>>>>> Thanks for the KIP. I think it would be useful to clarify > that > > > this > > > > >>>>>> is a > > > > >>>>>>>>> common scenario rather than an edge case, which further > > > > >>> demonstrates > > > > >>>>>> the > > > > >>>>>>>>> need for this optimization. For example: > > > > >>>>>>>>> A partition expansion is a common operational task in > Kafka: To > > > > >>>>>> balance > > > > >>>>>>>>> resource utilization and cost, topics are typically created > > > with a > > > > >>>>>>> moderate > > > > >>>>>>>>> default partition count. However, as traffic grows over > time, > > > it is > > > > >>>>>>> often > > > > >>>>>>>>> necessary to increase the number of partitions to > accommodate > > > the > > > > >>>>>> higher > > > > >>>>>>>>> workload. > > > > >>>>>>>>> > > > > >>>>>>>>> Regards > > > > >>>>>>>>> Jian > > > > >>>>>>>>> > > > > >>>>>>>>> 黃竣陽 <[email protected]> 于2026年5月30日周六 22:31写道： > > > > >>>>>>>>> > > > > >>>>>>>>>> Hello chia, > > > > >>>>>>>>>> > > > > >>>>>>>>>> Thanks for the comments, I have updated the KIP! > > > > >>>>>>>>>> > > > > >>>>>>>>>> Best Regards, > > > > >>>>>>>>>> Jiunn-Yang > > > > >>>>>>>>>> > > > > >>>>>>>>>>> Chia-Ping Tsai <[email protected]> 於 2026年5月30日 晚上8:29 > 寫道： > > > > >>>>>>>>>>> > > > > >>>>>>>>>>> Hi Jiunn-Yang, > > > > >>>>>>>>>>> > > > > >>>>>>>>>>> Would you mind removing the terms "hot" and "cold" when > > > > >>> describing > > > > >>>>>>>>>>> partitions in the KIP? I understand you are using them to > > > > >>> describe > > > > >>>>>> the > > > > >>>>>>>>>>> "freshness" or the users' need for the records, but > applying > > > > >>> these > > > > >>>>>>> terms > > > > >>>>>>>>>> to > > > > >>>>>>>>>>> the partition itself feels a bit unnatural. > > > > >>>>>>>>>>> > > > > >>>>>>>>>>> After all, in this scenario, users don't really care > whether > > > a > > > > >>>>>>> partition > > > > >>>>>>>>>> is > > > > >>>>>>>>>>> newly expanded or not. Their only expectation is that > they > > > won't > > > > >>>>>>> silently > > > > >>>>>>>>>>> lose any live records produced to the topic during their > > > active > > > > >>>>>>>>>> consumption. > > > > >>>>>>>>>>> > > > > >>>>>>>>>>> Best, Chia-Ping > > > > >>>>>>>>>>> > > > > >>>>>>>>>>> > > > > >>>>>>>>>>> > > > > >>>>>>>>>>> 黃竣陽 <[email protected]> 於 2026年5月30日週六 下午12:30寫道： > > > > >>>>>>>>>>> > > > > >>>>>>>>>>>> Hello Jun, > > > > >>>>>>>>>>>> > > > > >>>>>>>>>>>> Thanks for the feedback, I have updated the KIP > motivation > > > > >>>> section. > > > > >>>>>>>>>>>> > > > > >>>>>>>>>>>> Best Regards, > > > > >>>>>>>>>>>> Jiunn-Yang > > > > >>>>>>>>>>>> > > > > >>>>>>>>>>>>> Jun Rao via dev <[email protected]> 於 2026年5月30日 > > > 凌晨1:12 寫道： > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> Hi, Jiunn-Yang, > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> Thanks for the reply. I think we need a stronger > > > motivation for > > > > >>>>>> the > > > > >>>>>>>>>> KIP. > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> The KIP says "The core insight is that not all > partitions > > > > >>> without > > > > >>>>>> a > > > > >>>>>>>>>>>>> committed offset are the same. A newly expanded > partition > > > (hot) > > > > >>>> is > > > > >>>>>>>>>>>>> fundamentally different from a partition the consumer > has > > > never > > > > >>>>>> seen > > > > >>>>>>>>>>>>> because it predates the group (cold)." Why is the hot > > > partition > > > > >>>>>>>>>>>>> fundamentally different from the cold? > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> The KIP says "The existing by_duration policy is also > > > > >>>> insufficient > > > > >>>>>>>>>>>> because: > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> - The calculated seek time (now() - duration) varies > across > > > > >>> nodes > > > > >>>>>>> due > > > > >>>>>>>>>>>> to > > > > >>>>>>>>>>>>> clock skew. To be safe, users must set an overly large > > > > >>> duration, > > > > >>>>>>>>>>>> causing > > > > >>>>>>>>>>>>> unnecessary reprocessing. > > > > >>>>>>>>>>>>> - On network errors, the client recalculates the seek > time > > > on > > > > >>>>>> retry, > > > > >>>>>>>>>>>>> shifting the target timestamp forward and risking data > > > loss." > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> However, both of these situations are rare. If these > issues > > > > >>>>>> persist, > > > > >>>>>>>>>> more > > > > >>>>>>>>>>>>> severe problems likely exist elsewhere. Rare situations > > > don't > > > > >>>>>> need a > > > > >>>>>>>>>>>> common > > > > >>>>>>>>>>>>> solution. If users care about those rare situations, > they > > > can > > > > >>>>>>> implement > > > > >>>>>>>>>>>>> customized logic using > > > > >>>>>>>>>> ConsumerRebalanceListener.onPartitionsAssigned(). > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> Jun > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>> On Sun, May 17, 2026 at 6:50 AM 黃竣陽 < > [email protected]> > > > > >>> wrote: > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>>> Hello chia, > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>> Thanks for the feedback, > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>> If the creation time exists, the returned value > should > > > always > > > > >>>> be > > > > >>>>>>>>>>>> greater > > > > >>>>>>>>>>>>>> than or equal to zero, right? > > > > >>>>>>>>>>>>>> I have explicitly mentioned this in the KIP. > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> New Old (MetadataResponse v0–13) positive > any > > > > >>>>>>> field > > > > >>>>>>>>>>>>>> absent UnsupportedVersionException > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>> The earliest point at which we can detect the version > > > mismatch > > > > >>>> is > > > > >>>>>>>>>> during > > > > >>>>>>>>>>>>>> the > > > > >>>>>>>>>>>>>> first metadata fetch after assignment, which occurs > inside > > > > >>>>>> poll(). > > > > >>>>>>>>>>>>>> Therefore, the > > > > >>>>>>>>>>>>>> user would encounter an UnsupportedVersionException > from > > > > >>> poll(). > > > > >>>>>>> I’ll > > > > >>>>>>>>>>>>>> clarify this in the KIP. > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>> Best Regards, > > > > >>>>>>>>>>>>>> Jiunn-Yang > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>> Chia-Ping Tsai <[email protected]> 於 2026年5月17日 > > > 下午4:50 寫道： > > > > >>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>> hi Jiunn > > > > >>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> PartitionAgeMs (int64, default -1): The age of this > > > > >>> partition > > > > >>>>>> in > > > > >>>>>>>>>>>>>> milliseconds, computed server-side by the broker as > > > > >>>>>>>>>> broker_current_time > > > > >>>>>>>>>>>> - > > > > >>>>>>>>>>>>>> partition_creation_time. Returns -1 if the broker > does not > > > > >>>>>> support > > > > >>>>>>>>>> this > > > > >>>>>>>>>>>>>> feature or the partition creation time is unknown. > > > > >>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>> If the creation time exists, the returned value > should > > > always > > > > >>>> be > > > > >>>>>>>>>>>> greater > > > > >>>>>>>>>>>>>> than or equal to zero, right? > > > > >>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> New Old (MetadataResponse v0–13) positive > any > > > > >>>>>>> field > > > > >>>>>>>>>>>>>> absent UnsupportedVersionException > > > > >>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>> Will user encounter UnsupportedVersionException when > > > calling > > > > >>>>>>>>>> `poll()`? > > > > >>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>> Best, > > > > >>>>>>>>>>>>>>> Chia-Ping > > > > >>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>> On 2026/05/16 04:30:49 黃竣陽 wrote: > > > > >>>>>>>>>>>>>>>> Hello Jun, chia, > > > > >>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> I've updated KIP-1327 with a design change based on > the > > > > >>>>>>> discussion > > > > >>>>>>>>>>>>>>>> feedback. > > > > >>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> The updated design decouples the new-partition reset > > > > >>> behavior > > > > >>>>>>> from > > > > >>>>>>>>>>>>>>>> the base auto.offset.reset policy: > > > > >>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> - auto.offset.reset.max.age.ms now applies to all > > > > >>>>>>> auto.offset.reset > > > > >>>>>>>>>>>>>> values > > > > >>>>>>>>>>>>>>>> (latest, earliest, by_duration, none). > > > > >>>>>>>>>>>>>>>> - For new ("hot") partitions, the consumer resets to > > > > >>>>>>>>>>>>>> auto.offset.reset.new.partitions > > > > >>>>>>>>>>>>>>>> config setting > > > > >>>>>>>>>>>>>>>> - For existing ("cold") partitions, the base > > > > >>> auto.offset.reset > > > > >>>>>>>>>> policy > > > > >>>>>>>>>>>>>> continues > > > > >>>>>>>>>>>>>>>> to apply unchanged. > > > > >>>>>>>>>>>>>>>> - The new-partition reset behavior is represented > by a > > > > >>>> separate > > > > >>>>>>>>>>>>>> internal config > > > > >>>>>>>>>>>>>>>> (auto.offset.reset.new.partitions, currently fixed > to > > > > >>>>>> earliest). > > > > >>>>>>>>>> This > > > > >>>>>>>>>>>>>> decoupled design makes > > > > >>>>>>>>>>>>>>>> it straightforward to promote the behavior to a > public > > > > >>>>>>> user-facing > > > > >>>>>>>>>>>>>> configuration in a future KIP. > > > > >>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> Best Regards, > > > > >>>>>>>>>>>>>>>> Jiunn-Yang > > > > >>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>> Chia-Ping Tsai <[email protected]> 於 2026年5月16日 > > > 清晨7:46 > > > > >>> 寫道： > > > > >>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>> hi Jun > > > > >>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>> I see what you mean now. The proposal from me is > listed > > > > >>>> below: > > > > >>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>> 1) Add auto.offset.reset.new.partitions with a > default > > > > >>> value > > > > >>>>>> of > > > > >>>>>>>>>>>>>> earliest. It fixes the data loss from both > by_duration and > > > > >>>>>> latest, > > > > >>>>>>> and > > > > >>>>>>>>>>>> it > > > > >>>>>>>>>>>>>> does not change the logic of > auto.offset.reset=earliest. > > > > >>>>>>>>>>>>>>>>> 2) Mark auto.offset.reset.new.partitions as an > > > internal > > > > >>>>>>>>>>>>>> configuration. auto.offset.reset.new > .partitions=earliest > > > > >>>> already > > > > >>>>>>>>>>>>>> addresses the issue, and we can discuss the use cases > of > > > other > > > > >>>>>>> values > > > > >>>>>>>>>>>> in a > > > > >>>>>>>>>>>>>> separate KIP. > > > > >>>>>>>>>>>>>>>>> 3) Both configs, auto.offset.reset.new.partitions > and > > > > >>>>>>>>>>>>>> auto.offset.reset.latest.max.age.ms, will be applied > to > > > all > > > > >>> for > > > > >>>>>>>>>>>>>> consistency. > > > > >>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>> WDYT? > > > > >>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>> On 2026/05/15 20:53:20 Jun Rao via dev wrote: > > > > >>>>>>>>>>>>>>>>>> Hi, Chia-Ping, > > > > >>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>> Thanks for the reply. > > > > >>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>> 1. In the motivation section, the KIP says "When a > > > Kafka > > > > >>>>>> topic > > > > >>>>>>> is > > > > >>>>>>>>>>>>>> expanded > > > > >>>>>>>>>>>>>>>>>> with new partitions, consumers using the latest > auto > > > > >>> offset > > > > >>>>>>> reset > > > > >>>>>>>>>>>>>> policy > > > > >>>>>>>>>>>>>>>>>> will silently miss all records produced to those > > > > >>> partitions > > > > >>>>>>> before > > > > >>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>> consumer discovers them.". If a user sets > > > > >>>>>>>>>>>>>>>>>> auto.offset.reset=by_duration=1sec, the same > record > > > loss > > > > >>>>>> issue > > > > >>>>>>>>>> could > > > > >>>>>>>>>>>>>> also > > > > >>>>>>>>>>>>>>>>>> happen, right? > > > > >>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>> 2. I was thinking auto.offset.reset.new > .partitions > > > will > > > > >>>> take > > > > >>>>>>> the > > > > >>>>>>>>>>>> same > > > > >>>>>>>>>>>>>>>>>> values as auto.offset.reset. So a user could set > it > > > > >>>>>>> by_duration if > > > > >>>>>>>>>>>>>> needed. > > > > >>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>> Jun > > > > >>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>> On Thu, May 14, 2026 at 4:06 PM Chia-Ping Tsai < > > > > >>>>>>>>>> [email protected] > > > > >>>>>>>>>>>>> > > > > >>>>>>>>>>>>>> wrote: > > > > >>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> hi Jun > > > > >>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> Thanks for the feedback. I might be missing > something > > > > >>>>>>> important > > > > >>>>>>>>>>>> from > > > > >>>>>>>>>>>>>> your > > > > >>>>>>>>>>>>>>>>>>> suggestion, so please bear with me as I try to > > > clarify > > > > >>> with > > > > >>>>>> a > > > > >>>>>>> few > > > > >>>>>>>>>>>>>> questions: > > > > >>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> 1. Is there a strong use case for extending this > > > logic to > > > > >>>>>>> other > > > > >>>>>>>>>>>> reset > > > > >>>>>>>>>>>>>>>>>>> policies? Unlike latest, policies like earliest > or > > > > >>>>>> by_duration > > > > >>>>>>>>>>>> don't > > > > >>>>>>>>>>>>>> seem > > > > >>>>>>>>>>>>>>>>>>> to suffer from the same silent data loss issue > when a > > > > >>>>>>> partition > > > > >>>>>>>>>> is > > > > >>>>>>>>>>>>>> expanded. > > > > >>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> 2. What values would we expect users to > configure for > > > > >>>>>>>>>>>>>>>>>>> auto.offset.reset.new.partitions? If they set > it to > > > > >>>>>> earliest > > > > >>>>>>> or > > > > >>>>>>>>>>>>>> latest, > > > > >>>>>>>>>>>>>>>>>>> we might run into the exact same edge cases. For > > > example, > > > > >>>>>> if a > > > > >>>>>>>>>>>>>> consumer is > > > > >>>>>>>>>>>>>>>>>>> offline for a while and a new partition is > created > > > during > > > > >>>>>> that > > > > >>>>>>>>>>>>>> downtime, > > > > >>>>>>>>>>>>>>>>>>> the user might actually want to skip to latest > when > > > > >>>>>> resuming, > > > > >>>>>>>>>>>> rather > > > > >>>>>>>>>>>>>> than > > > > >>>>>>>>>>>>>>>>>>> reading from earliest just because the partition > is > > > > >>>>>>> technically > > > > >>>>>>>>>>>>>> "new" to > > > > >>>>>>>>>>>>>>>>>>> the group. > > > > >>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> This is exactly why we opted for introducing a > > > max.age > > > > >>>>>>> threshold. > > > > >>>>>>>>>>>> It > > > > >>>>>>>>>>>>>> gives > > > > >>>>>>>>>>>>>>>>>>> users a time-bound way to define what is > genuinely > > > > >>>> "hot/new" > > > > >>>>>>> and > > > > >>>>>>>>>>>>>> what is > > > > >>>>>>>>>>>>>>>>>>> just an old partition they haven't seen yet. > > > > >>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> Best, > > > > >>>>>>>>>>>>>>>>>>> Chia-Ping > > > > >>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> On 2026/05/14 20:48:09 Jun Rao via dev wrote: > > > > >>>>>>>>>>>>>>>>>>>> Hi, Jiunn-Yang, > > > > >>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>> Thanks for the KIP. > > > > >>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>> I find auto.offset.reset.latest.max.age a bit > > > weird. It > > > > >>>>>> only > > > > >>>>>>>>>>>>>> applies when > > > > >>>>>>>>>>>>>>>>>>>> auto.offset.reset is latest. However, it seems > that > > > the > > > > >>>>>>>>>> motivation > > > > >>>>>>>>>>>>>>>>>>> equally > > > > >>>>>>>>>>>>>>>>>>>> applies when auto.offset.reset is set to other > > > values > > > > >>> like > > > > >>>>>>>>>>>>>> by_duration. > > > > >>>>>>>>>>>>>>>>>>> The > > > > >>>>>>>>>>>>>>>>>>>> intention is that we want to have a separate > way to > > > > >>>> control > > > > >>>>>>>>>> newly > > > > >>>>>>>>>>>>>> created > > > > >>>>>>>>>>>>>>>>>>>> partitions vs existing partitions when the group > > > starts. > > > > >>>>>>> Have we > > > > >>>>>>>>>>>>>>>>>>> considered > > > > >>>>>>>>>>>>>>>>>>>> adding a new config like auto.offset.reset.new > > > > >>>> .partitions? > > > > >>>>>>> If > > > > >>>>>>>>>>>> this > > > > >>>>>>>>>>>>>> new > > > > >>>>>>>>>>>>>>>>>>>> config is not set, the offset reset policy > defaults > > > to > > > > >>> the > > > > >>>>>>>>>> policy > > > > >>>>>>>>>>>>>> used > > > > >>>>>>>>>>>>>>>>>>> for > > > > >>>>>>>>>>>>>>>>>>>> existing partitions. The user could set it > > > explicitly to > > > > >>>>>>>>>> customize > > > > >>>>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>>>> behavior for new partitions. > > > > >>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>> Jun > > > > >>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>> On Thu, May 7, 2026 at 5:07 AM 黃竣陽 < > > > [email protected]> > > > > >>>>>>> wrote: > > > > >>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>> Hi all, > > > > >>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>> I’d like to manually bump this thread. > > > > >>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>> Best Regards, > > > > >>>>>>>>>>>>>>>>>>>>> Jiunn-Yang > > > > >>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> 黃竣陽 <[email protected]> 於 2026年5月1日 晚上10:37 > 寫道： > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> Hello all, > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> Thanks for the feedback. > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> DJ01/DJ02: > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> MetadataResponse bumps from v13 to v14. The > > > > >>>>>>> PartitionMetadata > > > > >>>>>>>>>>>>>> struct > > > > >>>>>>>>>>>>>>>>>>>>> gains a new > > > > >>>>>>>>>>>>>>>>>>>>>> field PartitionAgeMs (int64, default -1), > computed > > > > >>>>>>> server-side > > > > >>>>>>>>>>>> by > > > > >>>>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>>>>> broker as > > > > >>>>>>>>>>>>>>>>>>>>>> broker_current_time - partition_creation_time. > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> Also add the consumer heartbeat flow. when > > > > >>>>>>> MembershipManager > > > > >>>>>>>>>>>>>> detects > > > > >>>>>>>>>>>>>>>>>>> a > > > > >>>>>>>>>>>>>>>>>>>>> newly assigned > > > > >>>>>>>>>>>>>>>>>>>>>> partition, it explicitly invalidates the > metadata > > > for > > > > >>>> the > > > > >>>>>>>>>>>> affected > > > > >>>>>>>>>>>>>>>>>>> topic > > > > >>>>>>>>>>>>>>>>>>>>> and forces a fresh MetadataRequest > > > > >>>>>>>>>>>>>>>>>>>>>> before making the offset reset decision, even > if > > > the > > > > >>>>>> topic > > > > >>>>>>> ID > > > > >>>>>>>>>> is > > > > >>>>>>>>>>>>>>>>>>> already > > > > >>>>>>>>>>>>>>>>>>>>> in the cache. > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> MB0: > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> The consumer learns the broker's maximum > supported > > > > >>>>>>>>>>>>>> MetadataResponse > > > > >>>>>>>>>>>>>>>>>>>>> version via the > > > > >>>>>>>>>>>>>>>>>>>>>> ApiVersions negotiation at connection time. > If the > > > > >>>>>>> negotiated > > > > >>>>>>>>>>>>>>>>>>> version is > > > > >>>>>>>>>>>>>>>>>>>>> unsupported, the consumer > > > > >>>>>>>>>>>>>>>>>>>>>> knows the broker does not support > PartitionAgeMs > > > at > > > > >>> all > > > > >>>>>> and > > > > >>>>>>>>>> can > > > > >>>>>>>>>>>>>>>>>>> throw an > > > > >>>>>>>>>>>>>>>>>>>>> UnsupportedVersionException > > > > >>>>>>>>>>>>>>>>>>>>>> immediately, rather than silently falling > back to > > > > >>> latest > > > > >>>>>>> and > > > > >>>>>>>>>>>>>> risking > > > > >>>>>>>>>>>>>>>>>>>>> data loss without any operator-visible signal. > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> MB1/MB2/MB3: > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> I have addressed these changes in the KIP. > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> Best Regards, > > > > >>>>>>>>>>>>>>>>>>>>>> Jiunn-Yang > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>> Chia-Ping Tsai <[email protected]> 於 > 2026年4月29日 > > > > >>>> 下午4:04 > > > > >>>>>>> 寫道： > > > > >>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>> hi David > > > > >>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>> I agree with the direction of moving the > 'age' > > > > >>>>>> resolution > > > > >>>>>>>>>> from > > > > >>>>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>>>>> Heartbeat API to the Metadata API to keep the > > > control > > > > >>>>>> plane > > > > >>>>>>>>>>>> clean. > > > > >>>>>>>>>>>>>> The > > > > >>>>>>>>>>>>>>>>>>> main > > > > >>>>>>>>>>>>>>>>>>>>> trade-off, as we noted before, is introducing > > > > >>>> inter-broker > > > > >>>>>>>>>> clock > > > > >>>>>>>>>>>>>> skew. > > > > >>>>>>>>>>>>>>>>>>> The > > > > >>>>>>>>>>>>>>>>>>>>> Group Coordinator approach provided a single > > > source of > > > > >>>>>> truth > > > > >>>>>>>>>> for > > > > >>>>>>>>>>>>>> time. > > > > >>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>> However, realistically, this time skew > should be > > > > >>>>>>> negligible. > > > > >>>>>>>>>>>>>> Given > > > > >>>>>>>>>>>>>>>>>>> that > > > > >>>>>>>>>>>>>>>>>>>>> the max.age threshold will likely be > configured in > > > > >>>> minutes > > > > >>>>>>> or > > > > >>>>>>>>>>>>>> hours, a > > > > >>>>>>>>>>>>>>>>>>>>> typical NTP skew (in milliseconds) between > brokers > > > > >>> won't > > > > >>>>>>> impact > > > > >>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>>>>> fallback decision. > > > > >>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>> Best, > > > > >>>>>>>>>>>>>>>>>>>>>>> Chia-Ping > > > > >>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>> David Jacot via dev <[email protected]> > 於 > > > > >>>>>> 2026年4月29日 > > > > >>>>>>>>>>>> 下午3:29 > > > > >>>>>>>>>>>>>> 寫道： > > > > >>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>> Hi all, > > > > >>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>> Thanks for the KIP! > > > > >>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>> Sorry, I haven't really followed the > previous > > > > >>>>>>> conversation > > > > >>>>>>>>>>>> but I > > > > >>>>>>>>>>>>>>>>>>> took a > > > > >>>>>>>>>>>>>>>>>>>>>>>> quick look at this one. > > > > >>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>> DJ01: I don't clearly understand the flow > with > > > the > > > > >>>>>>>>>>>>>>>>>>>>> ConsumerGroupHeartbeat > > > > >>>>>>>>>>>>>>>>>>>>>>>> API after reading the KIP. There is a new > > > boolean; > > > > >>> the > > > > >>>>>>> KIP > > > > >>>>>>>>>>>>>> states > > > > >>>>>>>>>>>>>>>>>>> that > > > > >>>>>>>>>>>>>>>>>>>>>>>> partition ages are returned only when this > > > boolean > > > > >>> is > > > > >>>>>>> set. > > > > >>>>>>>>>>>>>>>>>>> Implicitly, > > > > >>>>>>>>>>>>>>>>>>>>> this > > > > >>>>>>>>>>>>>>>>>>>>>>>> means that when the consumer receives a new > > > > >>> partition, > > > > >>>>>> it > > > > >>>>>>>>>> will > > > > >>>>>>>>>>>>>>>>>>> issue a > > > > >>>>>>>>>>>>>>>>>>>>> new > > > > >>>>>>>>>>>>>>>>>>>>>>>> HB request with the boolean set to receive > the > > > ages. > > > > >>>> Is > > > > >>>>>>> my > > > > >>>>>>>>>>>>>>>>>>>>> understanding > > > > >>>>>>>>>>>>>>>>>>>>>>>> correct? We should perhaps clarify the flow > and > > > also > > > > >>>>>>> explain > > > > >>>>>>>>>>>>>> how it > > > > >>>>>>>>>>>>>>>>>>>>> fits > > > > >>>>>>>>>>>>>>>>>>>>>>>> into the existing flow (e.g. list offsets, > fetch > > > > >>>>>> offsets, > > > > >>>>>>>>>>>> etc.). > > > > >>>>>>>>>>>>>>>>>>>>>>>> DJ02: It my understanding is correct, I > wonder > > > if > > > > >>>>>>>>>>>>>>>>>>>>>>>> the ConsumerGroupHeartbeat API is the right > > > place > > > > >>> for > > > > >>>>>>> this > > > > >>>>>>>>>>>> given > > > > >>>>>>>>>>>>>>>>>>> that > > > > >>>>>>>>>>>>>>>>>>>>> a new > > > > >>>>>>>>>>>>>>>>>>>>>>>> round trip is done anyway. Alternatively, it > > > could > > > > >>>>>> simply > > > > >>>>>>>>>>>>>> include > > > > >>>>>>>>>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>>>>>>>> metadata. Generally, we should be rather > > > cautious > > > > >>>> about > > > > >>>>>>> not > > > > >>>>>>>>>>>>>>>>>>> overloading > > > > >>>>>>>>>>>>>>>>>>>>>>>> the ConsumerGroupHeartbeat API with > unrelated > > > > >>>> concepts. > > > > >>>>>>> The > > > > >>>>>>>>>>>> API > > > > >>>>>>>>>>>>>> is > > > > >>>>>>>>>>>>>>>>>>> a > > > > >>>>>>>>>>>>>>>>>>>>>>>> control plane API for assigning or revoking > > > > >>>> partitions. > > > > >>>>>>> The > > > > >>>>>>>>>>>> fact > > > > >>>>>>>>>>>>>>>>>>> that > > > > >>>>>>>>>>>>>>>>>>>>> we > > > > >>>>>>>>>>>>>>>>>>>>>>>> don't want to add it to the corresponding > > > Streams > > > > >>> API > > > > >>>>>>> also > > > > >>>>>>>>>>>>>> suggests > > > > >>>>>>>>>>>>>>>>>>>>>>>> something is not quite right. What would we > do > > > if we > > > > >>>>>>> want to > > > > >>>>>>>>>>>>>>>>>>> support > > > > >>>>>>>>>>>>>>>>>>>>>>>> Streams in the future? > > > > >>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>> Best, > > > > >>>>>>>>>>>>>>>>>>>>>>>> David > > > > >>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> On Wed, Apr 29, 2026 at 12:28 AM Muralidhar > > > Basani > > > > >>>> via > > > > >>>>>>> dev > > > > >>>>>>>>>> < > > > > >>>>>>>>>>>>>>>>>>>>>>>>> [email protected]> wrote: > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> Hi Jiunn, > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> Thank you for this great kip. Good to know > > > about > > > > >>> the > > > > >>>>>>> gap. > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> mb-0 - why a new v2 version bump for > > > > >>>>>>> RequestPartitionAges > > > > >>>>>>>>>>>>>> field. > > > > >>>>>>>>>>>>>>>>>>> Can a > > > > >>>>>>>>>>>>>>>>>>>>>>>>> tagged field (for ex: on response, > > > PartitionAges on > > > > >>>>>>>>>>>>>>>>>>> TopicPartitions) > > > > >>>>>>>>>>>>>>>>>>>>> be > > > > >>>>>>>>>>>>>>>>>>>>>>>>> used here and avoid version bump? > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> mb-1 - For the new config, is there a > > > recommended > > > > >>>>>> value > > > > >>>>>>> or > > > > >>>>>>>>>> a > > > > >>>>>>>>>>>>>>>>>>> ConfigDef > > > > >>>>>>>>>>>>>>>>>>>>>>>>> validator? Probably it should based on the > > > > >>>>>>>>>>>> metadata.max.age.ms > > > > >>>>>>>>>>>>>> ? > > > > >>>>>>>>>>>>>>>>>>>>> Sizing > > > > >>>>>>>>>>>>>>>>>>>>>>>>> instructions can be part of javadocs I > guess. > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> mb-2 - (minor) As there are no changes to > Kafka > > > > >>>>>> Streams, > > > > >>>>>>>>>>>> would > > > > >>>>>>>>>>>>>> it > > > > >>>>>>>>>>>>>>>>>>> be > > > > >>>>>>>>>>>>>>>>>>>>> better > > > > >>>>>>>>>>>>>>>>>>>>>>>>> to add this new config > > > > >>>>>> auto.offset.reset.latest.max.age > > > > >>>>>>> to > > > > >>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>>>>>>>>> StreamsConfig block list > > > > >>>>>>>>>>>>>>>>>>> (NON_CONFIGURABLE_CONSUMER_DEFAULT_CONFIGS) > > > > >>>>>>>>>>>>>>>>>>>>> for a > > > > >>>>>>>>>>>>>>>>>>>>>>>>> clear warning, incase users configure it? > This > > > is > > > > >>> the > > > > >>>>>>> most > > > > >>>>>>>>>>>>>>>>>>> familiar > > > > >>>>>>>>>>>>>>>>>>>>>>>>> consumer config and users might easily > > > mistakenly > > > > >>>>>>> configure > > > > >>>>>>>>>>>>>> it. Or > > > > >>>>>>>>>>>>>>>>>>>>> may be > > > > >>>>>>>>>>>>>>>>>>>>>>>>> it's not worth it to add. > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> mb-3 - (minor) The phrasing "the consumer > falls > > > > >>> back > > > > >>>>>> to > > > > >>>>>>>>>>>>>> earliest" > > > > >>>>>>>>>>>>>>>>>>>>> reads as > > > > >>>>>>>>>>>>>>>>>>>>>>>>> if the config were being changed > per-partition > > > > >>> which > > > > >>>>>>> isn't > > > > >>>>>>>>>>>>>>>>>>> supported. > > > > >>>>>>>>>>>>>>>>>>>>> May > > > > >>>>>>>>>>>>>>>>>>>>>>>>> be rephrasing to something like "consumer > > > resolves > > > > >>>> the > > > > >>>>>>>>>>>> initial > > > > >>>>>>>>>>>>>>>>>>>>> position to > > > > >>>>>>>>>>>>>>>>>>>>>>>>> start offset for that partition" as if > > > earliest was > > > > >>>>>>> applied > > > > >>>>>>>>>>>> to > > > > >>>>>>>>>>>>>>>>>>> that > > > > >>>>>>>>>>>>>>>>>>>>>>>>> partition only and auto.offset.reset > config is > > > > >>>>>>> unchanged. > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> Thanks, > > > > >>>>>>>>>>>>>>>>>>>>>>>>> Murali > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> On Tue, Apr 28, 2026 at 2:48 PM 黃竣陽 < > > > > >>>>>>> [email protected]> > > > > >>>>>>>>>>>>>> wrote: > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> Hi chia, > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> I have updated the KIP to include this > change. > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> Best Regards, > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> Jiunn-Yang > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> Chia-Ping Tsai <[email protected]> 於 > > > > >>> 2026年4月28日 > > > > >>>>>>> 晚上8:03 > > > > >>>>>>>>>>>> 寫道： > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> hi Jiunn-Yang > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> chia_0: Should we expose the partition > > > creation > > > > >>>> time > > > > >>>>>>> via > > > > >>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>>> Admin > > > > >>>>>>>>>>>>>>>>>>>>> API? > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> I assume it would be valuable for users to > > > > >>> diagnose > > > > >>>>>> and > > > > >>>>>>>>>>>>>>>>>>> troubleshoot > > > > >>>>>>>>>>>>>>>>>>>>> the > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> behavior of > auto.offset.reset.latest.max.age > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> Best, > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> Chia-Ping > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>> On 2026/04/28 10:47:58 黃竣陽 wrote: > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> Hello everyone, > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> I would like to start a discussion on > > > KIP-1327 > > > > >>>>>>> Prevent > > > > >>>>>>>>>> Hot > > > > >>>>>>>>>>>>>> Data > > > > >>>>>>>>>>>>>>>>>>>>> Loss > > > > >>>>>>>>>>>>>>>>>>>>>>>>> on > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> Partition Expansion for Latest Policy > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> < > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>> > > > > >>>>>>>>>> > > > > >>>>>>> > > > > >>>>>> > > > > >>>> > > > > >>> > > > > https://urldefense.com/v3/__https://cwiki.apache.org/confluence/x/KY4mGQ__;!!Ayb5sqE7!qF4q1QzF1RRgP61D7A2xuEai1ky7fepKDKFFvpNBuePikH-ULmT87TvuuZzy5kau5E4y5zMZAmfQQiwZomM$ > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> This proposal aims to introduces > > > > >>>>>>>>>>>>>>>>>>> auto.offset.reset.latest.max.age, > > > > >>>>>>>>>>>>>>>>>>>>> a > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> consumer config that lets the > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> latest reset policy distinguish newly > > > expanded > > > > >>>>>> (hot) > > > > >>>>>>>>>>>>>> partitions > > > > >>>>>>>>>>>>>>>>>>>>> from > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> long-existing (cold) ones. Partitions > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> younger than the configured threshold > > > > >>>> automatically > > > > >>>>>>> fall > > > > >>>>>>>>>>>>>> back > > > > >>>>>>>>>>>>>>>>>>> to > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> earliest, preventing silent data loss > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> during topic expansion without forcing a > > > full > > > > >>>>>>> historical > > > > >>>>>>>>>>>>>>>>>>> reprocess. > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> Best regards, > > > > >>>>>>>>>>>>>>>>>>>>>>>>>>>> Jiunn-Yang > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>>>> > > > > >>>>>>>>>>>> > > > > >>>>>>>>>>>> > > > > >>>>>>>>>> > > > > >>>>>>>>>> > > > > >>>>>>>> > > > > >>>>>>> > > > > >>>>>>> > > > > >>>>>> > > > > >>>> > > > > >>>> > > > > >>> > > > > >> > > > > > > > > > > > > > > > > > >
