Details
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Improvement
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Status: Resolved
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Critical
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Resolution: Fixed
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Impala 2.10.0, Impala 2.11.0, Impala 3.0, Impala 2.12.0, Impala 2.13.0
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ghx-label-3
Description
After IMPALA-4794, in a distinct aggregation, data will be shuffled on grouping exprs and distinct expr. It works well if the NDV of grouping exprs is low, but is an regression otherwise. We should provide a query operation to disable IMPALA-4794 and probably look to do smarter planning in the future.
Attachments
Issue Links
- is caused by
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IMPALA-4794 Impala's count(distinct ...) plans are not robust to data skew
- Resolved