2010YOUY01 opened a new pull request, #24262: URL: https://github.com/apache/datafusion/pull/24262
## 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. --> Part of https://github.com/apache/datafusion/issues/22710 Depends on https://github.com/apache/datafusion/pull/24261 Only the last commit belongs to this PR. I’ll rebase onto main after the dependent PR is merged. ## 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. Please explain the problem you are trying to solve in terms of the user-visible behavior, rather than the implementation. For example, "The code in `foo.rs` doesn't handle nulls" is a symptom of the implementation. "COUNT(DISTINCT) returns wrong results when the column contains nulls" is the user-visible problem. --> For `PartialReduce` aggregation, this PR handles the memory limit by returning an error immediately. Note that the existing behavior when `PartialReduce` runs out of memory is to spill and then perform final streaming aggregation. This behavior is implemented in the legacy code: https://github.com/apache/datafusion/pull/20019 However, the original PR does not discuss the intended OOM behavior, and there are no tests specifically covering it. For the major use case of `PartialReduce` aggregation—reducing data locally before shuffle ([https://github.com/datafusion-contrib/datafusion-distributed/issues/360)—I](https://github.com/datafusion-contrib/datafusion-distributed/issues/360)%E2%80%94I) think early emission may actually be the intended behavior. I tend to believe the existing behavior was an auto-completion from AI, instead of an intentional design decision. Therefore, this PR takes the more conservative approach of returning an error on OOM. We can revisit and improve this behavior in follow-up PRs. ## 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. --> For the background of the refactor, see EPIC issue for details For the key changes in this PR, see `partial_reduce_stream.rs` ## 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)? --> UTs ## Are there any user-facing changes? <!-- 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 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]
