hjtran opened a new issue, #30580: URL: https://github.com/apache/beam/issues/30580
### What happened? If you specify a side input to `CombineGlobally`, you end up with a pretty inscrutable error (from an end user's perspective) that comes from pipeline translation. It looks like the combiner lifting phase improperly assumes that combine transforms will only have a single input pcollection. Reproducing example: https://play.beam.apache.org/?sdk=python&shared=vjM_k2TvNrf ```python def combineglobally_function(test=None): # [START combineglobally_function] import apache_beam as beam def get_common_items(sets, side): # set.intersection() takes multiple sets as separete arguments. # We unpack the `sets` list into multiple arguments with the * operator. # The combine transform might give us an empty list of `sets`, # so we use a list with an empty set as a default value. return set.intersection(*(sets or [set()])) with beam.Pipeline() as pipeline: pc = (pipeline | beam.Create([1])) common_items = ( pipeline | 'Create produce' >> beam.Create([ {'🍓', '🥕', '🍌', '🍅', '🌶️'}, {'🍇', '🥕', '🥝', '🍅', '🥔'}, {'🍉', '🥕', '🍆', '🍅', '🍍'}, {'🥑', '🥕', '🌽', '🍅', '🥥'}, ]) | 'Get common items' >> beam.CombineGlobally(get_common_items, side=beam.pvalue.AsSingleton(pc)) | beam.Map(print)) # [END combineglobally_function] if test: test(common_items) if __name__ == '__main__': combineglobally_function() ``` (Code in case the playground links expires) ### Issue Priority Priority: 3 (minor) ### Issue Components - [ ] Component: Python SDK - [X] Component: Java SDK - [ ] Component: Go SDK - [ ] Component: Typescript SDK - [ ] Component: IO connector - [ ] Component: Beam YAML - [ ] Component: Beam examples - [ ] Component: Beam playground - [ ] Component: Beam katas - [ ] Component: Website - [ ] Component: Spark Runner - [ ] Component: Flink Runner - [ ] Component: Samza Runner - [ ] Component: Twister2 Runner - [ ] Component: Hazelcast Jet Runner - [ ] Component: Google Cloud Dataflow Runner -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
