Hi Alex, That's correct. The n refers to the n-th checkpoint. The checkpoint ID is important, because operators need to align the barriers to ensure that they consumed all inputs up to the point, where the barriers were injected into the stream. Each operator checkpoints its own state. For sources, this could be the reading offset in a Kafka topic, or path and the byte offset in a file, etc.
Cheers, Fabian 2018-04-24 10:47 GMT+02:00 Alexander Smirnov <alexander.smirn...@gmail.com>: > ok, I got it. Barrier-n is an indicator or n-th checkpoint. > > My first impression was that barriers are carrying offset information, but > it was wrong. > > Thanks for unblocking ;-) > > Alex >
