2010YOUY01 opened a new pull request, #26069: URL: https://github.com/apache/datafusion/pull/26069
## 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. --> This is primarily a simplifying refactor, with an optimizer regression fix piggy-backed on top (an inefficient plan shape, not a correctness issue): - https://github.com/apache/datafusion/pull/25983#issuecomment-5976014730 The optimizer fix itself is only a one-line change. If this simplification is not desirable, I'll open a replacement PR containing just the direct fix. ## 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. --> ## Part 1: Optimizer fix See sqllogictest diff for the reproducer I'll mark the fix in comments ## Part 2: Optimizer simplification During different stages in physical optimization, a logical aggregation can be either ``` AggregateExec(mode=final) --AggregateExec(mode=partial) AggregateExec(mode=single) AggregateExec(mode=final) --RepartitionExec ----AggregateExec(mode=partial) ``` So the existing implementation is using a nested dfs (the closure has another dfs inside, to match non-consecutive aggregates) try to match all of the 3 cases. However, after looking at related optimizer rules: - initial physical planning - CombinePartialFinalAggregate - EnsureDistributions - and this rule We can find only case 1 is possible, so the implementation can be simplified into a naive pattern matching ``` Find the exact below shape, and try push limits LimitExec --AggregateExec(mode=final) ----AggregateExec(mode=partial) ``` ## 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. --> - simplify an optimizer rule according to the above rationale - fix a small bug ## What is the testing strategy for this PR? <!-- 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 Briefly describe how this PR is tested, and point to the specific tests you added. For example: 'This new feature is covered by the `sqllogictest` cases added in `foo.slt`'. If this PR does not add tests, explain why. For example, if the change is already covered by existing tests, please mention it. You should also check the `codecov` bot reply on this PR to confirm the changed code is exercised. --> - for bug fix, changes in `slt` - To ensure refactor correctness: no e2e test need to be changed ## 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]
