Rich-T-kid opened a new pull request, #10094: URL: https://github.com/apache/arrow-rs/pull/10094
# Which issue does this PR close? Closes #10017. <!-- We generally require a GitHub issue to be filed for all bug fixes and enhancements and this helps us generate change logs for our releases. You can link an issue to this PR using the GitHub syntax. --> - Closes #10017. # Rationale for this change <!-- Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed. Explaining clearly why changes are proposed helps reviewers understand your changes and offer better suggestions for fixes. --> `RunArray::slice()` kept the full physical run_ends and values buffers, so downstream operations (e.g. length(), sort, take) would iterate over physical runs outside the logical slice range. This is wasted work proportional to how narrow the slice is relative to the full array. # What changes are included in this PR? <!-- There is no need to duplicate the description in the issue here but it is sometimes worth providing a summary of the individual changes in this PR. --> - `RunArray::slice()` now trims values and run_ends to only the physical runs that overlap the logical slice range. - Trimmed run_ends are normalized: each entry has the logical offset subtracted and is capped at logical_length, so the result is self-describing. Double-slicing is safe. - Added early-return guard in logical_nulls() for zero-length arrays. # Are these changes tested? <!-- We typically require tests for all PRs in order to: 1. Prevent the code from being accidentally broken by subsequent changes 2. Serve as another way to document the expected behavior of the code If tests are not included in your PR, please explain why (for example, are they covered by existing tests)? If this PR claims a performance improvement, please include evidence such as benchmark results. --> Yes - Added unit tests in arrow-array covering single-run slices, multi-boundary slices, and repeated nested slices. (mod slice_trim_values) - Added a test in arrow-string demonstrating that length() on a sliced REE touches only the trimmed physical runs. # Are there any user-facing changes? no <!-- If there are user-facing changes then we may require documentation to be updated before approving the PR. If there are any breaking changes to public APIs, please call them out. --> -- 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]
