[Ismaël Mejía]

Hello,

I was testing a pipeline that produces SessionWindows and then calculates a
Mean afterwards in 'batch' mode and I found this issue while running with
the Flink Runner.

​17/02/08 09:27:24 INFO
org.apache.beam.runners.flink.translation.FlinkBatchPipelineTranslator: |
|   |   |   visitPrimitiveTransform- 19b75b2bGroupByKey
Exception in thread "main" java.lang.UnsupportedOperationException: Merging
WindowFn with windows other than IntervalWindow are not supported.
    at
org.apache.beam.runners.flink.translation.FlinkBatchTransformTranslators$GroupByKeyTranslatorBatch.translateNode(FlinkBatchTransformTranslators.java:247)
    at
org.apache.beam.runners.flink.translation.FlinkBatchTransformTranslators$GroupByKeyTranslatorBatch.translateNode(FlinkBatchTransformTranslators.java:180)
    at
org.apache.beam.runners.flink.translation.FlinkBatchPipelineTranslator.applyBatchTransform(FlinkBatchPipelineTranslator.java:116)​

I rapidly look through the JIRAs, and I could not find if there was a JIRA
tracking this case, is there any work on this ? Is there a conceptual
problem on flink to do this, or it is just that some work is needed ?

Thanks,
Ismaël