[connortsui20]

Summary

Every grouped is_sorted and is_constant call fails with "Return DType mismatch". Both finalize methods read the result field out of the nullable partial struct, which gives Bool? while the return dtype is a non-nullable Bool. #11188 found the is_sorted case, and its grouped pushdown test covers only min_max because of it.

Changes

Both finalize methods now fill null partials. A null partial comes from an empty or null group and is the empty state, so each fill uses the verdict that finalize_scalar already gives that state: true for is_sorted (vacuously sorted) and false for is_constant. Grouped and scalar results now agree. Note that a null group gets the same verdict as an empty group, since the partial can't tell them apart and the return dtype is non-nullable.

Each aggregate gets a grouped test that puts empty, all-null, and null groups next to ordinary ones.

[codspeed]

Merging this PR will improve performance by 22.47%

1 warning

⚠️ Walltime results may be unreliable

Some benchmarks used the Walltime instrument outside CodSpeed Macro Runners, which can make the results inconsistent.

Learn more about Macro Runners

See affected benchmarks

⚡ 1 improved benchmark
✅ 1769 untouched benchmarks
⏩ 105 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	CPU Simulation	missing_stats[16]	92.8 µs	75.8 µs	+22.47%

Tip

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_{Comparing ct/grouped-is-sorted-finalize (47a34bd) with develop (3be54de)}

Footnotes

1. 105 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩