srowen commented on a change in pull request #24890: [SPARK-28074][SS] Log warn message on possible correctness issue for multiple stateful operations in single query URL: https://github.com/apache/spark/pull/24890#discussion_r329316644
########## File path: docs/structured-streaming-programming-guide.md ########## @@ -1647,6 +1648,26 @@ For example, sorting on the input stream is not supported, as it requires keepin track of all the data received in the stream. This is therefore fundamentally hard to execute efficiently. +### Limitation of global watermark + +In Append mode, some stateful operations could emit rows older than current watermark plus allowed late record delay, +which are "late rows" in downstream stateful operations (as Spark uses global watermark) and these rows can be discarded. Review comment: can be discarded implies that it's OK to discard them. Are you saying "may be discarded"? Then I'd say "if a stateful operation emits rows older ... note that these rows may be discarded" ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
