UBarney commented on issue #15676: URL: https://github.com/apache/datafusion/issues/15676#issuecomment-2796526975
> I think the undeterministic is based on the input not order-preserved, so if the input is order-preserved, we can have deterministic result for first/last. Just to clarify, what does "order-preserved" mean exactly? Does it only refer to a single partition with ordered input, or can the order be determined by ORDER BY fields? > If ordering is specified, it returns the first value among those "last values" with the same ordering keys, due to the performance reason I don't understand why we *should* "return the first value among those "last values" with the same ordering keys". If the ordering keys are the same, the result may still be non-deterministic unless the input is ordered and in a single partition. -- 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: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
