neilconway opened a new issue, #22929: URL: https://github.com/apache/datafusion/issues/22929
### Is your feature request related to a problem or challenge? Right now, `LeftSemi` consumes the entire probe side before emitting _any_ output rows. This isn't fundamental: we could check which probe row flips the visited bitmap from 0 -> 1, and arrange for the output row to be produced at that point. This would enable better pipeline parallelism. It would probably also improve partitioning behavior: `LeftSemi` + `CollectLeft` emits everything in a single output partition today, which isn't great. Would need to check if this needs stronger memory ordering requirements when flipping bits than we can get away with today. ### Describe the solution you'd like _No response_ ### Describe alternatives you've considered _No response_ ### Additional context _No response_ -- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
