[Data][Cherry-pick] Prevent Limit from getting pushed past map_groups (#60881)#60893
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aslonnie merged 2 commits intoreleases/2.54.0from Feb 10, 2026
Merged
[Data][Cherry-pick] Prevent Limit from getting pushed past map_groups (#60881)#60893aslonnie merged 2 commits intoreleases/2.54.0from
Limit from getting pushed past map_groups (#60881)#60893aslonnie merged 2 commits intoreleases/2.54.0from
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This PR updates `map_groups` to assume that the UDF might change the row count. This change is necessary to fix a bug where `Limit` gets incorrectly pushed past the `map_groups` (fixes #60872). For more context, see: * #60448 * #60756 --------- Signed-off-by: Balaji Veeramani <bveeramani@berkeley.edu>
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This pull request addresses a bug in Ray Data's optimizer where a Limit operation could be incorrectly pushed down past a map_groups operation. The map_groups operation was incorrectly marked as not modifying row counts, which is now fixed by setting udf_modifying_row_count=True. This ensures that optimizations like limit pushdown are not applied when they could lead to incorrect results. A new test case has been added to verify that the Limit operation is no longer pushed past map_groups by default, confirming the fix. The changes are correct and well-tested.
alexeykudinkin
approved these changes
Feb 9, 2026
iamjustinhsu
approved these changes
Feb 9, 2026
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Cherry-pick of #60881