2010YOUY01 opened a new pull request, #18161: URL: https://github.com/apache/datafusion/pull/18161
## Which issue does this PR close? <!-- 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. For example `Closes #123` indicates that this PR will close issue #123. --> https://github.com/apache/datafusion/issues/18070 ## 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. --> See the above issue and its comment https://github.com/apache/datafusion/issues/18070#issuecomment-3419730649 ## 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. --> In nested loop join, when the join column includes `List(Utf8View)`, use `take()` instead of `to_array_of_size()` to avoid deep copying the utf8 buffers inside `Utf8View` array. This is the quick fix, avoiding deep copy inside `to_array_of_size()` is a bit tricky. Here is `ListArray`'s physical layout: https://arrow.apache.org/rust/arrow/array/struct.GenericListArray.html If multiple elements is pointing to the same list range, the underlying payload can't be reused.So the potential fix in `to_array_of_size` can only avoids copying the inner-inner utf8view array buffers, but can't avoid copying the inner array (i.e. views are still copied), and deep copying for other primitive types also can't be avoided. Seems this can be better solved when `ListView` type is ready 🤔 ### Benchmark I tried query 1 in https://github.com/apache/datafusion/issues/18070 49.0.0: 4s PR: 4s Now the performance are similar, I suspect the most time is spend evaluating the expensive `array_has` so the optimization in https://github.com/apache/datafusion/pull/16996 can't help much. ## 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)? --> Existing tests ## Are there any user-facing changes? <!-- If there are user-facing changes then we may require documentation to be updated before approving the PR. --> No <!-- If there are any breaking changes to public APIs, please add the `api change` label. --> -- 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]
