Regarding the option to integrate repair logic in "latest", I understand your concern about this approach: backward compatibility. But we should have a consensus: the problem of data loss due to expand partitions is indeed caused by kafka's own design mechanism. The user configuration "latest" may be due to the consideration of not wanting to consume from earliest when firstly deploy app, or too much lag, or consumption exceeds the maximum offset, and then consume directly from the latest. As for expanding partition, the user will definitely not want to consume from the latest, unless he clearly knows what this means. Therefore, it is necessary to solve this problem, at the same time, without causing other problems. Therefore, for the method of adding an "init.offset.reset" option, there will be a problem, that is, this configuration must be set to "earliest" to avoid this situation, but it will also cause the new group to be consumed from earliest. , which goes against the idea of consuming from the latest at the beginning (brings other problems). The same is true for the method of setting auto.offset.reset to "earliest" and seekingToEnd on new deployments: in order to avoid this case, "auto.offset.reset" has no choice but to set "earliest", when the consumption is advanced, it will also reset to the earliest, causing duplication (bringing other problems). So I think it's best to fix it in a black box to fundamentally solve it. It does not require users to perceive this problem, nor does the user's understanding of "auto.offset.reset" need to be changed, and there will be no complexity caused by redundant parameter configuration(and users doesn't necessarily know how to combine these parameters to use it). As for the compatibility issue, I think it is enough to enrich the test cases after the repair, what do you think?
"Matthias J. Sax" <mj...@apache.org>写道： > I am not sure if we can/should change the behavior of existing > "latest/earliest" due to backward compatibility concerns. While I agree > that many users might not know the fine details how both behave, it > would still be a change that might break other people that do understand > the details and rely on it. > > I also agree that having both "latest" and "safe_latest" might be > difficult, as users might not know which one to choose? > > Maybe we should have two configs instead of one? `auto.offset.reset`, as > the name suggests, resets the offset automatically, and thus it's > current behavior is actually well defined and sound. -- What seems to be > missing is an `init.offset` config that is only used if there is _no_ > committed offsets, but it's not used when the consumer has a position > already (either via getting a committed offset or via seek())? > > > For the original use-case you mentioned, that you want to start from > "latest" when the app starts, but if a new partition is added you want > to start from "earliest" it seem that the right approach would be to > actually configure "earliest", and when the app is deployed for the > first time, use a `seekToEnd()` to avoid triggering auto-offset-reset? > > > Thoughts? > > > -Matthias > > > On 7/1/22 6:03 AM, hudeqi wrote: > > Thanks for your attention and reply. > > Having chatted with Guozhang Wang at KAFKA-12478 before, I came up with an > > idea similar to yours. It's just not implemented on the client side, but on > > the server side: Firstly, find out all the groups subscribed to this topic > > before extending partitions, and then let these groups commit an initial > > offset 0 for these new expanded partitions (also using adminClient). > > Finally, the real process of adding partitions is carried out. In this way, > > the problem can also be completely solved. > > > > Best, > > hudeqi > > > > "Matthew Howlett" <m...@confluent.io.INVALID>写道： > >> My first reaction also is that the proposed configuration is surely too > >> complicated. > >> > >> It seems like an ideal solution from a usability perspective (always a good > >> place to start) would be if the consumer just automatically behaved in this > >> way. To make that work: > >> 1. auto.offset.reset=latest would need to behave like > >> auto.offset.reset=earliest in the case where a consumer is in a group, and > >> is assigned a newly created partition. This might seem a bit too "magic", > >> but from the perspective of the group, I think it makes conceptual sense > >> and people wouldn't find it surprising. Also, I don't think anyone would be > >> relying on the old behavior. > >> 2. The group would need to detect the newly created partitions and > >> rebalance pretty quickly (this is not the case currently). The longer the > >> delay, the more tenuous the idea of changing the auto.offset.reset behavior > >> in this special circumstance. > >> > >> I have a feeling this approach has implementation challenges (haven't > >> thought deeply), just throwing it out there. > >> > >> > >> On Wed, Jun 29, 2022 at 4:57 AM David Jacot <da...@apache.org> wrote: > >> > >>> Thanks for the KIP. > >>> > >>> I read it and I am also worried by the complexity of the new > >>> configurations. They are not easy to grasp. I need to digest it a bit > >>> more, > >>> I think. > >>> > >>> Best, > >>> David > >>> > >>> Le mer. 29 juin 2022 à 02:25, Matthias J. Sax <mj...@apache.org> a écrit : > >>> > >>>> Thanks for the KIP. > >>>> > >>>> I don't think I fully digested the proposal yet, but my first reaction > >>>> is: this is quite complicated. Frankly, I am worried about complexity > >>>> and usability. > >>>> > >>>> Especially the option `safe_latest` is a "weird" one IMHO, and `nearest` > >>>> is even more complex. > >>>> > >>>> The problem at hand (as I understand it from the Jira) is a real one, > >>>> but I am wondering if it would be something that should be addressed by > >>>> the application? If you pass in strategy `none`, and a new partition is > >>>> added, you can react to it by custom code. For regular startup you can > >>>> still go with "latest" to avoid reprocessing the history. > >>>> > >>>> Adding "latest/earliest_on_start" seems useful, as it seems to also > >>>> address https://issues.apache.org/jira/browse/KAFKA-3370 > >>>> > >>>> > >>>> -Matthias > >>>> > >>>> > >>>> On 6/7/22 12:55 AM, hudeqi wrote: > >>>>> I think so too, what about Guozhang Wang and Luke Chen? Can I initiate > >>> a > >>>> voting process? > >>>>> > >>>>> Best, > >>>>> hudeqi > >>>>> > >>>>> > -----原始邮件----- > >>>>> > 发件人: "邓子明" <dengzim...@growingio.com> > >>>>> > 发送时间: 2022-06-07 10:23:37 (星期二) > >>>>> > 收件人: dev@kafka.apache.org > >>>>> > 抄送: > >>>>> > 主题: Re: [DISCUSS] KIP-842: Add richer group offset reset > >>> mechanisms > >>>>> > > >>>>> </dengzim...@growingio.com> > >>>> > >>>
