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 > > > > > > > > > > >
