Thanks Uladzislau for the KIP. Good that the KIP is already accepted and sorry for being so late. I just have a few minor suggestions that might improve the KIP, but of course it’s up to you whether you want to update it.
AS1: Could we add a note to the Compatibility/Migration section covering lambda partitioners: (a) they will bind to the deprecated method and emit deprecation warnings, (b) they cannot access headers without being rewritten as a class, and (c) they will require a signature change at 5.0 when the old method is removed. AS2: Can headers ever be null? Also Headers is mutable, but in in StreamPartitioner they must be immutable? Just document it? (headers is read-only within partitions(...) and mutating it has undefined behavior). This ensures nobody relies on partition-time header edits leaking into the produced record. Thanks, Alieh On Fri, Jun 5, 2026 at 2:14 PM Uladzislau Blok <[email protected]> wrote: > Hello Matthias, > > I think it makes sense to deprecate the non-header version. If users > have their own implementation of a partitioner, they will have enough > time to update it. KIP was updated. > > Since there are no major questions for KIP, I will start the voting > thread. Thanks for the review. > > Regards, > Uladzislau Blok. > > On Wed, Jun 3, 2026 at 11:57 PM Matthias J. Sax <[email protected]> wrote: > > > > Thanks for the KIP Uladzislau, and sorry for late reply... Mailing list > > is way too busy. > > > > > > Overall the KIP make sense to me. I am just wondering if we should > > deprecate the exiting `partitions(...)` methods, allowing us to remove > > it with AK 5.0 (including to change the new `partitions(... Headers)` > > one to _not_ have a default implementation? > > > > > > > > -Matthias > > > > > > On 5/3/26 3:28 AM, Uladzislau Blok wrote: > > > Fixed link: > > > KIP-1321: > https://urldefense.com/v3/__https://cwiki.apache.org/confluence/x/pYwmGQ__;!!Ayb5sqE7!r4jw6IsZsgsr1vql8HqfzT6lAExaOPrse43LTGD0f26UzLLJAKX3DzKwVwdC8C_ITynzeP7c6HPUg3kCDA$ > > > > > >> On Sun, May 3, 2026 at 12:23 PM Uladzislau Blok <[email protected]> > wrote: > > >> > > >> Hello All, > > >> > > >> I would like to start a discussion on KIP-1321: Headers Aware > StreamPartitioner. This need was identified while implementing headers > support for state stores (KIP-1271). > > >> > > >> The proposal involves adding a default method to the public interface > and propagating headers to the underlying serde. This change will enable > users to build custom partitioners based on header information. > > >> > > >> KIP-1321: > https://urldefense.com/v3/__https://cwiki.apache.org/confluence/x/phttps:/*cwiki.apache.org/confluence/x/pYwmGQYwmGQ__;Lw!!Ayb5sqE7!r4jw6IsZsgsr1vql8HqfzT6lAExaOPrse43LTGD0f26UzLLJAKX3DzKwVwdC8C_ITynzeP7c6HPPhwWP5Q$ > > >> > > >> Best regards, > > >> Uladzislau Blok > > >> > > >> > > >> On Sun, May 3, 2026 at 12:19 PM Uladzislau Blok <[email protected]> > wrote: > > >>> > > >>> Hello All, > > >>> > > >>> I'd like to start discussion on headers aware streams partitioner, > which we found out while implementing headers support for state stores > > >>> > > >>> KIP: > > >>> > https://urldefense.com/v3/__https://cwiki.apache.org/confluence/x/pYwmGQ__;!!Ayb5sqE7!r4jw6IsZsgsr1vql8HqfzT6lAExaOPrse43LTGD0f26UzLLJAKX3DzKwVwdC8C_ITynzeP7c6HPUg3kCDA$ > > >
