Re: Streams - merging multiple topics

[Brian Krahmer]

Thanks Damian!  Based on your response, I finally got it working.  I did 
end up using left joins and added a final step that goes from table -> 
stream and then filters out nulls.

thanks,
brian

On 21.11.2016 22:03, Damian Guy wrote:
Hi Brian,

It sounds like you might want do something like:

KTable inputOne = builder.table("input-one");
KTable inputTwo = builder.table("input-two");
KTable inputThree = builder.table("input-three");
ValueJoiner joiner1 = //...
ValueJoiner joiner2 = //...

inputOne.join(inputTwo, joiner1)
                .join(inputThree, joiner2)
                .to(outputTopic)

This would result in the join logic being triggered when any record arrives
in any of the input topics. There will be some de-duplication of results
written to the output topic. If you want immediate output then you will
want to set StreamsConfig.CACHE_MAX_BYTES_BUFFERING_CONFIG = 0. You should
create and configure the output topic yourself before you run your streams
app (so you can make it compacted etc).

Thanks,
Damian