Thanks. Presumably, if transactions are added to kafka then you get exactly-once semantics anyway. Any word on transactions and release date for that?
> On 14 Jan 2016, at 16:58, Guozhang Wang <wangg...@gmail.com> wrote: > > Hello Tom, > > There is no specific release date planned yet, but we are shooting for > adding kafka-streams in the next major release of Kafka. > > Regarding exactly-once semantics, the first version of kafka-streams may > not yet have this feature implemented but we do have designs and target to > add it in a later release this year. > > Guozhang > > On Thu, Jan 14, 2016 at 3:17 AM, Tom Dearman <tom.dear...@gmail.com> wrote: > >> Can anyone tell me whether the kaka-streams project will resolve the issue >> noted in the KIP-28: >> >> “After processor writes to a store instance, it first sends the change >> message to its corresponding changelog topic partition. When user calls >> commit() in his processor, KStream needs to flush both the store instance >> as well as the producer sending to the changelog, as well as committing the >> offset in the upstream Kafka. If these three operations cannot be done >> atomically, then if there is a crash in between this operations duplicates >> could be generated since the upstream Kafka committing offset is executed >> in the last step; if there three operations can be done atomically, then we >> can guarantee "exactly-once" semantics.” >> >> Does this requirement essentially mean that kafka-streams will not work >> until transactional support is implemented in kafka. Is kafka-streams going >> to be in the 0.10 release. Is transactional support still going into >> release 0.10 and does this look likely to be for Q2 2016 which is the >> present schedule. >> >> Thanks. >> >> >> > > > -- > -- Guozhang
