Fix Partial AggregateExec correctness issue dropping rows #18712
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xanderbailey
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xanderbailey
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Nov 15, 2025
| // Check if we should switch to skip aggregation mode | ||
| // It's important that we do this before we early emit since we've | ||
| // already updated the probe. | ||
| if let Some(new_state) = self.switch_to_skip_aggregation()? { |
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It's unclear to me why we set update_skip_aggregation_probe here https://github.com/apache/datafusion/pull/18712/files#diff-69c8ecaca5e2c7005f2ed1facaa41f80b45bfd006f2357e53ff3072f535c287dL687 and not next to switch_to_skip_aggregation. I can't fully give an explanation yet but allowing the probe to be updated and then allowing the look to break before we get here seems dangerous? It's important that we emit everything before we move to the SkipAggregation state?
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| ExecutionState::Done => { | ||
| // Sanity check: all groups should have been emitted by now | ||
| if !self.group_values.is_empty() { |
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Adding some protection here to try and avoid bugs like this happening in the future.
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I'd rather fail the query than return the wrong / incomplete results.
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Which issue does this PR close?
More detail is in the issue.
Rationale for this change
This is a pretty major correctness issue.
What changes are included in this PR?
Fixes issue and reorders skip aggregate and emit early within partial aggregate execution
Are these changes tested?
Yes, the unit test that's added here previously failed before this change.
Are there any user-facing changes?