haraldrombaut edited a comment on pull request #14294: URL: https://github.com/apache/beam/pull/14294#issuecomment-804884719
> > Beam PCollections do not guarantee ordering of elements > > I think what would be useful to know from the author, is what they would expect the result to be if they set this key in beam. > > @victuos, were you expecting the result of this to be message ordering preserved end to end through your pipeline? If so, that may not be the result here. We would expect that when a consumer of a subscription, with ordering enabled, would receive the outputted messages (with the same ordering key) in the order they were published. The order in which these messages are published is as far as I know determined by the timestamp of each element. Being able to set the ordering key will not ensure end to end in order message processing. But if we group elements in a window by the ordering key, and output those elements with a specific timestamp, we can ensure they're published in order (for that window) and ordering can be enabled on subscriptions. -- 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: [email protected]
