Hi devs, In Spark structured streaming, chained stateful operators possibly produces incorrect results under the global watermark. SPARK-33259 (https://issues.apache.org/jira/browse/SPARK-33259) has an example demostrating what the correctness issue could be.
Currently we don't prevent users running such queries. Because the possible correctness in chained stateful operators in streaming query is not straightforward for users. From users perspective, it will possibly be considered as a Spark bug like SPARK-33259. It is also possible the worse case, users are not aware of the correctness issue and use wrong results. IMO, it is better to disable such queries and let users choose to run the query if they understand there is such risk, instead of implicitly running the query and let users to find out correctness issue by themselves. I would like to propose to disable the streaming query with possible correctness issue in chained stateful operators. The behavior can be controlled by a SQL config, so if users understand the risk and still want to run the query, they can disable the check. In the PR (https://github.com/apache/spark/pull/30210), the concern I got for now is, this changes current behavior and by default it will break some existing streaming queries. But I think it is pretty easy to disable the check with the new config. In the PR currently there is no objection but suggestion to hear more voices. Please let me know if you have some thoughts. Thanks. Liang-Chi Hsieh -- Sent from: http://apache-spark-developers-list.1001551.n3.nabble.com/ --------------------------------------------------------------------- To unsubscribe e-mail: dev-unsubscr...@spark.apache.org
