If I read the code correctly, the operation on this line prepares the input
for the (stringSerde, stringSerde) specified on line 142:
.leftJoin(userRegionsTable, (clicks: Long, region: String) => (if
(region == null) "UNKNOWN" else region, clicks))
FYI
On Sat, Feb 10, 2018 at 11:00 AM, Debasish Ghosh <ghosh.debas...@gmail.com>
wrote:
> Hi -
>
> I was going through this example at
> https://github.com/confluentinc/kafka-streams-
> examples/blob/3.3.x/src/test/scala/io/confluent/examples/streams/
> StreamToTableJoinScalaIntegrationTest.scala,
> especially the leftJoin part
> https://github.com/confluentinc/kafka-streams-
> examples/blob/3.3.x/src/test/scala/io/confluent/examples/streams/
> StreamToTableJoinScalaIntegrationTest.scala#L156.
> This leftJoin returns KStream[String, (String, Long)], while default
> serializers are String for both key and value as in
> https://github.com/confluentinc/kafka-streams-
> examples/blob/3.3.x/src/test/scala/io/confluent/examples/streams/
> StreamToTableJoinScalaIntegrationTest.scala#L112-L113.
> My question is how does this serialization work here ? I mean how does the
> tuple get serialized with the default serializers ? And leftJoin only works
> with default serializers ..
>
> regards.
>
> --
> Debasish Ghosh
> http://manning.com/ghosh2
> http://manning.com/ghosh
>
> Twttr: @debasishg
> Blog: http://debasishg.blogspot.com
> Code: http://github.com/debasishg
>
