sunchao opened a new issue, #5500: URL: https://github.com/apache/datafusion-comet/issues/5500
### Describe the bug `CometObjectHashAggregate` returns `None` when Comet shuffle is disabled without attaching a fallback reason. This is a pre-existing diagnostics gap identified while reviewing #5421, not a regression from that PR's aggregate-buffer repair. The shuffle guard in [the reviewed source](https://github.com/apache/datafusion-comet/blob/cfa311307b8430e7f70a9744122f2aa7bdd30c55/spark/src/main/scala/org/apache/spark/sql/comet/operators.scala#L2024-L2036) bypasses `doConvert` and does not call `withFallbackReason`. The strict unexplained-fallback check can therefore report an unannotated decline, or a reason collected from another node can obscure this particular cause. ### Steps to reproduce Add a focused serde/planner regression for `ObjectHashAggregateExec`, such as grouped `collect_list` over an eligible Parquet input with `spark.sql.execution.useObjectHashAggregateExec=true` and `spark.comet.shuffle.enabled=false`. Check the shuffle-disabled guard directly and the resulting extended-explain reason; run the regression with `spark.comet.explain.fallback.strict.enabled` both enabled and disabled. The missing annotation is verified from the guard's source. A separate end-to-end strict-mode reproduction has not been run for this issue. ### Expected behavior The deliberate decline should carry an accurate shuffle-disabled reason, without changing aggregate execution eligibility or masking an unrelated missing explanation. ### Additional context The [review discussion](https://github.com/apache/datafusion-comet/pull/5421#issuecomment-5429161669) explicitly separates this issue from the buffer-compatibility fix. #5499 tracks stale fallback-reason provenance; this issue covers a specific missing reason at its source. -- 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]
