Hi Alieh, Thanks for the KIP!
I agree with everything stated so far. In the KIP, we are deprecating the `isTimestamped` field and the associated getter, but the `DslStoreFormat` enum only specifies `DEFAULT` and `HEADERS`. I'm assuming we are going to add some additional types to the DslStoreFormat enum to include timestamped types? Otherwise this looks good to me. Thanks, Bill On Mon, Feb 23, 2026 at 8:48 AM Alieh Saeedi via dev <[email protected]> wrote: > Thanks Matthias. > > Good points! I updated the KIP accordingly. > > Bests > Alieh > > On Mon, Feb 23, 2026 at 11:15 AM Lucas Brutschy via dev < > [email protected]> wrote: > > > Thanks for the updates Alieh! > > > > On Sun, Feb 22, 2026 at 8:52 PM Matthias J. Sax <[email protected]> > wrote: > > > > > > Thanks Alieh. > > > > > > I like Lucas' idea about "format" vs "type". > > > > > > > > > For the downgrade path, KIP-1271 says: > > > > > > > Downgrades are not supported; the only way to achieve one is by > > deleting the local store and rebuilding it from the changelog. > > > > > > While KIP-1285 only say: > > > > > > > The same as in KIP-1271, downgrades are not supported. > > > > > > Might be good to align both? > > > > > > > > > > > > One last question: Should we call out that > > > `Materialized.as(KeyValueBytesStoreSupplier)` (same for window and > > > session case), will also allow to enable a headers store on a per-store > > > basis, similar to the plain-kv / ts-case? Ie, if one uses > > > > > > > Materialized.as( > > > > Stores.persistentTimestampedKeyValueStoreWithHeaders(...) > > > > ) > > > > > > The corresponding DSL operator would also use a header store, > > > overwriting whatever is configured via `StreamsConfig`. > > > > > > > > > While it's unfortunately not well documented, it is currently possible > > > to pass in both types of supplier, and the DSL would "bridge" between > > > both store types. Thus, it's currently possible, to disable ts-stores > in > > > the DSL via > > > > > > > Materialized.as( > > > > Stores.persistentKeyValueStore(...) > > > > ) > > > > > > The determining factor is, if the passed-in supplier implements > > > `TimestampedBytesStore` or not and we added a similar marker interface > > > `HeaderBytesStore` with KIP-1271, to we can do the same thing for > header > > > stores. > > > > > > This should not imply any more code changes I believe, but should work > > > this way automatically base on KIP-1285 proposal. I think it's mainly > an > > > documentation question. > > > > > > > > > > > > -Matthias > > > > > > > > > > > > > > > On 2/22/26 6:16 AM, Alieh Saeedi via dev wrote: > > > > Thanks Lucas for the feedback. > > > > > > > > LB1) dsl.store.type makes sense to me, but I’m not attached to it. I > > can > > > > change it (and already have changed it) to dsl.store.format if we > > prefer > > > > that naming. > > > > > > > > LB2) Since Kafka Streams does not have a timestamped session store, > we > > > > don’t have any DslSessionParams constructor with isTimestamped. What > > we > > > > are deprecating in the KIP is the older constructor that does not > take > > a > > > > DslStoreType (now DslStoreFormat). To keep things cleaner, we only > > keep a > > > > single constructor that also includes DslStoreFormat. For session > > stores, > > > > DEFAULT corresponds to the regular session store, and HEADERS > > corresponds > > > > to SessionStoreWithHeaders. This detail is already mentioned in the > > KIP. > > > > > > > > LB3) Because this KIP does not introduce any new state store formats, > > the > > > > upgrade and downgrade paths are identical to those described in > > KIP-1271. > > > > I’ve added this note to the KIP as well. > > > > > > > > Thanks, > > > > Alieh > > > > > > > > On Fri, Feb 20, 2026 at 9:08 PM Lucas Brutschy < > [email protected] > > > > > > > wrote: > > > > > > > >> Hi Alieh, > > > >> > > > >> Thanks for the KIP. A few thoughts below. > > > >> > > > >> LB1: The config name dsl.store.type feels a bit ambiguous since we > > > >> already have dsl.store.suppliers.class (which controls RocksDB vs. > > > >> in-memory). dsl.store.type could be confused with that distinction. > > > >> Would something like dsl.store.format be clearer, since this is > really > > > >> about the value format (timestamped vs. timestamped+headers)? > > > >> > > > >> LB2: Regarding DslSessionParams: the current code entirely lacks an > > > >> isTimestamped field or constructor parameter. The KIP shows > > > >> deprecating a constructor with isTimestamped on DslSessionParams, > but > > > >> that constructor does not exist today. Could you clarify whether the > > > >> KIP intends to add and immediately deprecate the constructor, or > > > >> whether the old DslSessionParams constructor should simply remain > > > >> as-is and a new overload with DslStoreType should be added alongside > > > >> it? > > > >> > > > >> LB3: Regarding compatibility, the KIP mentions that switching from > > > >> DEFAULT to HEADERS triggers KIP-1271 upgrade paths. It would be good > > > >> to clarify whether switching back from HEADERS to DEFAULT is also > > > >> supported (i.e., is it a two-way migration or one-way only?). If it > is > > > >> one-way, that must be documented explicitly. > > > >> > > > >> Thanks, > > > >> Lucas > > > >> > > > >> On Fri, Feb 20, 2026 at 10:30 AM Alieh Saeedi via dev > > > >> <[email protected]> wrote: > > > >>> > > > >>> Hey Matthias, > > > >>> Thanks for the suggestions. I agree with all of them. They all make > > sense > > > >>> to me. I updated the KIP accordingly. > > > >>> > > > >>> Bests, > > > >>> Alieh > > > >>> > > > >>> On Thu, Feb 19, 2026 at 8:33 PM Matthias J. Sax <[email protected]> > > > >> wrote: > > > >>> > > > >>>> Thanks for the KIP. Great follow up to KIP-1271. > > > >>>> > > > >>>> > > > >>>> > > > >>>> Nit: The `DSL_STORE_TYPE_DOC` should be `private` and I also think > > we > > > >>>> can improve the wording -- but that's more of am impl detail, not > > > >> really > > > >>>> critical for the KIP itself. > > > >>>> > > > >>>> How about: > > > >>>> > > > >>>> "Controls the state store type used by the DSL store supplier (see > > > >>>> config 'dsl.store.suppliers.class'). 'default' uses timestamped > > stores. > > > >>>> 'headers' uses the headers-aware stores." > > > >>>> > > > >>>> > > > >>>> > > > >>>> MJS1: Should we deprecate the existing `DslKeyValueParams(final > > String > > > >>>> name, final boolean isTimestamped)` constructor, and make the > newly > > > >>>> introduced "type" a mandatory parameter? (Cf MJS2 below) > > > >>>> > > > >>>> > > > >>>> > > > >>>> MJS2: Should we add new enum `DslStoreType` with DEFAULT and > HEADERS > > > >>>> value, and change the constructor > > > >>>> > > > >>>> from > > > >>>> - DslKeyValueParams(final String name, final boolean > > isTimestamped, > > > >>>> final boolean isHeadersEnabled) > > > >>>> > > > >>>> to > > > >>>> - DslKeyValueParams(final String name, final DslStoreType > > storeType) > > > >>>> > > > >>>> This would more align to the newly added String config (and the > KIP > > > >>>> calls out that we did not want to add a boolean config, what makes > > > >> sense > > > >>>> to me), and would subsume the existing `isTimestamped` parameter > on > > the > > > >>>> existing constructor which we could remove (Cf MJS1) > > > >>>> > > > >>>> [We have a similar thing for `group.protocol` config.] > > > >>>> > > > >>>> > > > >>>> If yes, wondering if we should also deprecate `isTimestamped()` > and > > not > > > >>>> add `headersEnabled()` but instead add `storeType()` getter? > > > >>>> > > > >>>> Similar for window/session Dsl*Parameter classes. > > > >>>> > > > >>>> > > > >>>> > > > >>>> -Matthias > > > >>>> > > > >>>> > > > >>>> On 2/18/26 3:30 AM, Alieh Saeedi via dev wrote: > > > >>>>> Hi all, > > > >>>>> > > > >>>>> I’d like to start a discussion on a new KIP, KIP-1285: DSL Opt-in > > > >> Support > > > >>>>> for Header-Aware State Stores. > > > >>>>> > > > >>>>> KIP-1271 introduced headers-aware state stores in Kafka Streams. > > > >> KIP-1285 > > > >>>>> proposes adding corresponding DSL-level opt-in support, so that > DSL > > > >>>>> applications can take advantage of these headers-aware stores > while > > > >>>> keeping > > > >>>>> existing applications and topologies unchanged by default. > > > >>>>> > > > >>>>> You can find the KIP here: > > > >>>>> > > > >>>>> > > > >>>> > > > >> > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-1285%3A+DSL+Opt-in+Support+for+Header-Aware+State+Stores > > > >>>>> > > > >>>>> Feedback would be greatly appreciated. > > > >>>>> > > > >>>>> Best, > > > >>>>> Alieh > > > >>>>> > > > >>>> > > > >>>> > > > >> > > > > > > > > > >
