Hi Ning, Answer you question:
*And why is rich functions not allowed here?* If you need access to the state API, you can consider using ProcessWindowFunction[1], which allows you to use ProcessWindowFunction. Thanks, vino. [1]: https://ci.apache.org/projects/flink/flink-docs-release-1.6/dev/stream/operators/windows.html#processwindowfunction Ning Shi <nings...@gmail.com> 于2018年9月10日周一 上午11:28写道： > Since the aggregate() function on a keyed window stream does not allow > using rich functions, I can only use an AggregateFunction. Is the > accumulator state of the AggregateFunction backed by RocksDB and > persisted in checkpoints if I use the RocksDB backend. My job looks > like the following, > > sourceStream.keyBy(…) > .timeWindow(Time.seconds(…)) > .trigger(CountTrigger.of(…)) > .aggregate(new MyAggFunc()); > > Since the stream has high cardinality keys, each window could have > millions of them. If the accumulator state is not backed by RocksDB, > there might be a lot of data stored on the heap. > > And why is rich functions not allowed here? > > Thanks, > > — > Ning >
