You can read about assigning unique IDs to stateful operators in the docs [1][2]. What the uid() method does is to establish a stable and unique identifier for a stateful operator. Then as you evolve your application, this helps ensure that future versions of your job will be able to restore savepoints taken by earlier versions and find the state they need, despite changes to the topology.
The two uids specified in those two independent jobs (the streaming RidesAndFaresSolution job and the batch ReadRidesAndFaresSnapshot job) must match -- in other words, the strings must be the same. But there's nothing in that example that ensures this will be the case. Regards, David [1] https://ci.apache.org/projects/flink/flink-docs-release-1.12/ops/production_ready.html#set-uuids-for-all-operators [2] https://ci.apache.org/projects/flink/flink-docs-release-1.12/ops/state/savepoints.html#assigning-operator-ids On Fri, Apr 30, 2021 at 4:52 PM Abdullah bin Omar < abdullahbinoma...@gmail.com> wrote: > Hi, > > when we readstate of of savepooint, we use, "myuid" as a argument of the > function. For example, > > DataSet<KeyedState> keyedState = savepoint.readKeyedState("my-uid", new > ReaderFunction()); > > > *Question 1:* > > In [1] (line no 79), we get the "uid" with datastream. Then in [2] (line > no 45), *how can we use the "uid" that we have got from in [1]?* Because > in [2], there is no declaration of using the "uid" from [1]. > > *Question 2:* > > *what does it mean by "uid" in the datastream of [1]?* is it something a > unique user identification for each stream or for each state of the > datastream? > > > [1] > https://github.com/ververica/flink-training/blob/master/rides-and-fares/src/solution/java/org/apache/flink/training/solutions/ridesandfares/RidesAndFaresSolution.java > [2] > https://github.com/ververica/flink-training/blob/master/state-processor/src/main/java/com/ververica/flink/training/exercises/ReadRidesAndFaresSnapshot.java > > Thank you > > >
