lukecwik edited a comment on issue #11406: [BEAM-9748] Move Reparallelize 
transform to Reshuffle
URL: https://github.com/apache/beam/pull/11406#issuecomment-614121831
 
 
   > The comments inside Reparallelize explain how this transform differs from 
Reshuffle.viaRandomKey(): it performs dramatically better on Dataflow in case 
the input PCollection is generated highly sequentially, as in the case of 
reading several GB of JDBC results. It almost certainly performs somewhat worse 
if the input PCollection is generated in a well-parallelized way, but I haven't 
measured that; I haven't measured the former case for non-Dataflow runners 
either.
   > 
   > I think it's reasonable to move this to Reshuffle, but rename it to 
something more clear: maybe Reshuffle.forSequentiallyGeneratedInput()?
   
   This was true at some point in time for Dataflow but I don't think we have 
rerun benchmarks to see how it performs now. Shuffle performance has improved a 
lot while side input performance has remained relatively flat for the iterable 
use case.

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