kotwal-itpro opened a new pull request, #29394:
URL: https://github.com/apache/flink/pull/29394
## What is the purpose of the change
`SELECT DISTINCT * FROM (... GROUP BY ROLLUP(k))` returns duplicate rows
when a group key is NULL. `FlinkRelMdUniqueKeys` and
`FlinkRelMdColumnUniqueness` report the group keys of every `Aggregate` as
unique, so `FlinkAggregateRemoveRule` drops the DISTINCT. With grouping sets,
the row of the NULL group can equal the rolled-up row.
## Brief change log
- Report the group keys as unique only for simple aggregates or when nulls
are ignored, matching Calcite's `RelMdUniqueKeys` / `RelMdColumnUniqueness`.
## Verifying this change
- Added `GroupingSetsITCase#testDistinctOnRollupWithNullGroupKey` (the query
from the JIRA). It returns two rows without the fix, one with it.
- Metadata, grouping-sets and aggregate-remove suites pass unchanged (298
tests).
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? no
- If yes, how is the feature documented? not applicable
---
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Generated-by: Claude Opus 5.5
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