simonepri commented on pull request #12421: URL: https://github.com/apache/beam/pull/12421#issuecomment-666763106
> In practice, having no elements at all is so uncommon, it's not reasonable to include that in basic utility transforms, since they never apply, and no data = no compute is a better condition to maintain. I agree it is uncommon, but still it is probably good to have some sane default for common operations. For instance (when in doubt) it might be a good idea (or maybe not) to be consistent with what happen in SQL. In SQL the sum of an empty set is null (i.e. in our case an empty PCollection), while the count of an empty set is 0. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org