PDE Question 94

Community Discussion

Written by other learners. Comments can disagree with the marked answer — check the official documentation when in doubt.

• 2

  Side inputs In addition to the main input PCollection, you can provide additional inputs to a ParDo transform in the form of side inputs. A side input is an additional input that your DoFn can access each time it processes an element in the input PCollection. When you specify a side input, you create a view of some other data that can be read from within the ParDo transform’s DoFn while processing each element. Side inputs are useful if your ParDo needs to inject additional data when processing each element in the input PCollection, but the additional data needs to be determined at runtime (and not hard-coded). Such values might be determined by the input data, or depend on a different branch of your pipeline.

• 2

  https://beam.apache.org/documentation/programming-guide/#side-inputs

• 1

  Why not side-output?