[DISCUSS] KIP-904 Kafka Streams - Guarantee subtractor is called before adder if key has not changed

[Fq Public <fq...@gmail.com>]

Hi everyone,

I'd like to share a new KIP for discussion:
https://cwiki.apache.org/confluence/x/P5VbDg

This could be considered mostly as a "bug fix" but we wanted to raise a KIP
for discussion because it involves changes to the serialization format of
an internal topic which raises backward compatibility considerations.

Please take a look and let me know what you think.

Thanks,
Farooq

Re: [DISCUSS] KIP-904 Kafka Streams - Guarantee subtractor is called before adder if key has not changed

[Guozhang Wang <gu...@gmail.com>]

Hello Farooq,

Thanks for the very detailed proposal! I think this is a great idea.
Just a few thoughts:

1. I regret that we over-optimized the Changed serde format for
footprint while making it less extensible. It seems to me that a two
rolling bounce migration is unavoidable.. Regarding the format, I'm
just thinking if we can change the type of "INT newDataLength" to
UINT32?

2. `.equals` default implementation on Object is by reference, so if
the groupBy did not generate a new object, that may still pass. This
means that even if user does not implement the `.equals` function, if
the same object is returned then this feature would still be
triggered, is that correct?


Guozhang

On Mon, Feb 6, 2023 at 5:05 AM Fq Public <fq...@gmail.com> wrote:
>
> Hi everyone,
>
> I'd like to share a new KIP for discussion:
> https://cwiki.apache.org/confluence/x/P5VbDg
>
> This could be considered mostly as a "bug fix" but we wanted to raise a KIP
> for discussion because it involves changes to the serialization format of
> an internal topic which raises backward compatibility considerations.
>
> Please take a look and let me know what you think.
>
> Thanks,
> Farooq