A large cause of coder inference issues is due to type erasure in Java[1]. For your example, I would suspect that it should have worked since your ConcatWordsCombineFn doesn't have any type variables declared. Can you add the message and stacktrace for the exception that is failing here[2] to your question?
1: https://stackoverflow.com/q/53235553/4368200 2: https://github.com/apache/beam/blob/7c8530d550e5d687d5601b9fb09d6dbd6acb0302/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Combine.java#L2186 On Wed, Jun 5, 2019 at 5:00 AM Massy Bourennani <[email protected]> wrote: > Hi, > > I'm looking for some help on Apache Airflow. Here is the SO post: > > https://stackoverflow.com/questions/56443416/why-apache-beam-cant-infer-the-default-coder-when-using-kvstring-string > > Many thanks, > Massy >
