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fix: GROUP BY returns two rows for the NULL group with a nullable UNIQUE constraint - #24103

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LDM-A:ldm/datafusion-23820
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fix: GROUP BY returns two rows for the NULL group with a nullable UNIQUE constraint#24103
LDM-A wants to merge 3 commits into
apache:mainfrom
LDM-A:ldm/datafusion-23820

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@LDM-A LDM-A commented Aug 5, 2026 •
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Which issue does this PR close?

Rationale for this change

Explained accordingly in the issue linked above.

What changes are included in this PR?

  1. Introduces a "duplicate_nulls" field to "FunctionalDependence" to distinguish UNIQUE constraints from PRIMARY_KEY constraints.
  2. Skips UNIQUE dependencies in "get_target_functional_dependencies" so dependent columns are no longer added to GROUP_BY
  3. Adds "get_nullable_unique_target_functional_dependencies" to identify targets of UNIQUE dependencies.

Are these changes tested?

Yes exisiting tests created by @alamb previously.

Are there any user-facing changes?

No public API changes

@github-actions github-actions Bot added sql SQL Planner common Related to common crate labels Aug 5, 2026
@LDM-A
LDM-A marked this pull request as draft August 5, 2026 11:35
@LDM-A
LDM-A marked this pull request as ready for review August 5, 2026 11:42
@LDM-A
LDM-A marked this pull request as draft August 5, 2026 11:50
@github-actions github-actions Bot added the sqllogictest SQL Logic Tests (.slt) label Aug 5, 2026
@LDM-A
LDM-A marked this pull request as ready for review August 5, 2026 12:28
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Incorrect results: GROUP BY returns two rows for the NULL group with a nullable UNIQUE constraint

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