psolomin opened a new issue, #26041: URL: https://github.com/apache/beam/issues/26041
### What happened? My pipeline is consuming from streaming source (AWS Kinesis) and writes to parquet files once per minute. When restarting it from a Flink snapshot, I was unable to get exactly-once delivery of the records into the final files. 1. When using standard file-naming policy, I get files like `out-2023-03-29T22-45-00.000Z-2023-03-29T22-46-00.000Z-00000-of-00004.parquet`. I've noticed that, after a restart, some of the window files are replaced, which causes records to be lost. 2. I've created a JobId var which is re-generated every time the app starts, which gives file names like `out-<JobId>-2023-03-29T22-45-00.000Z-2023-03-29T22-46-00.000Z-00000-of-00004.parquet` - this allows me to avoid having replaced files and lost records, but introduces duplicates. The file names are made via https://github.com/psolomin/beam-playground/blob/e0f1834d6ee76a796d6d21836e1d04140e6d9ca2/kinesis-io-with-enhanced-fan-out/src/main/java/com/psolomin/consumer/NoColonFileNaming.java#L16 (2) effectively makes the pipeline to be at-least-once. Also, when the app fails and Flink restarts it, I don't see neither duplicates, nor lost records, and exactly-once semantic actually works as expected. I've tried different setting of the window: ``` Window.<KinesisRecord>into(FixedWindows.of(Duration.standardSeconds(60))) ``` ``` Window.<KinesisRecord>into(FixedWindows.of(Duration.standardSeconds(60))) .withAllowedLateness(Duration.ZERO) <- changing this to greater numbers had no effect .discardingFiredPanes() .triggering(Repeatedly.forever(AfterProcessingTime.pastFirstElementInPane() .plusDelayOf(Duration.standardSeconds(60)))) ``` Is it expected behaviour? Is it documented anywhere? Is there a configuration combo of savepoint config and window config which preserves exaclty-once when the app is stopped and started from a savepoint? ### Issue Priority Priority: 3 (minor) ### Issue Components - [ ] Component: Python SDK - [X] Component: Java SDK - [ ] Component: Go SDK - [ ] Component: Typescript SDK - [ ] Component: IO connector - [ ] Component: Beam examples - [ ] Component: Beam playground - [ ] Component: Beam katas - [ ] Component: Website - [ ] Component: Spark Runner - [X] Component: Flink Runner - [ ] Component: Samza Runner - [ ] Component: Twister2 Runner - [ ] Component: Hazelcast Jet Runner - [ ] Component: Google Cloud Dataflow Runner -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
