haohuaijin opened a new issue, #10967: URL: https://github.com/apache/arrow-rs/issues/10967
### Is your feature request related to a problem or challenge? When both `RowSelection::and_then` operands are mask-backed, the current implementation maps each selected inner row to a set bit in the outer mask. This is efficient for sparse masks but expensive for large, dense masks. ### Describe the solution you'd like Add a word-at-a-time bitmap expansion path for dense masks while retaining the existing implementation for other inputs. Based on benchmarks, use the new path when: - the outer mask has at least 8,192 rows; - outer selectivity is approximately 75% or greater; and - inner selectivity is approximately 5% or greater. On an Apple M4, all 104 benchmark cases selected by these thresholds improved over `main`, with mean execution time reduced by 30.0% to 97.9%. ### 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]
