You can have a look at https://github.com/apache/kafka/blob/trunk/streams/src/main/java/org/apache/kafka/streams/kstream/internals/KGroupedStreamImpl.java#L150 for an example. Obviously exactly-once semantics for Kafka haven't been completed, so this would be at-least-once.
On Wed, 25 Jan 2017 at 08:43 Nick DeCoursin <[email protected]> wrote: > From the documentation > <http://docs.confluent.io/3.1.1/streams/developer-guide.html#id3>: > > The counting operation for record streams is trivial to implement: you can > > maintain a local state store that tracks the latest count for each key, > > and, upon receiving a new record, update the corresponding key by > > incrementing its count by one. > > > How? Is there any examples of this online? To me, it doesn't seem so > trivial because there's no such thing as a transaction in Kafka, > > Thank you, > Nick > > -- > > Nick DeCoursin > Software Engineer > foodpanda > > Tel | +1 920 450 5434 <(920)%20450-5434> > > Mail | [email protected] > > Skype | nick.foodpanda > > Foodpanda GmbH | Schreiberhauer Str. 30 | 10317 Berlin | Germany > Sitz der Gesellschaft | Berlin, AG Charlottenburg | HRB 138224 B | > USt-ID-Nr | DE 283789080 > Geschäftsführer | Benjamin Bauer, Felix Plog, Ralf Wenzel > > CONFIDENTIALITY NOTICE: This message (including any attachments) is > confidential and may be privileged. It may be read, copied and used only by > the intended recipient. If you have received it in error please contact the > sender (by return e-mail) immediately and delete this message. Any > unauthorized use or dissemination of this message in whole or in parts is > strictly prohibited. >
