perf: Optimize scalar fast path for iszero#19919
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Jefffrey merged 2 commits intoapache:mainfrom Jan 22, 2026
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| assert!(booleans.value(1)); | ||
| assert!(!booleans.value(2)); | ||
| assert!(booleans.value(3)); | ||
| let array = Arc::new(Float32Array::from(vec![1.0, 0.0, 3.0, -0.0])); |
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Could we move the tests to SLTs
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Do you want all of the unit test removed from here or only the new ones I added? All of these are already covered in slt.
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It would be good if we can do it for all the tests there
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| Test | Coverage Status |
|---|---|
| test_iszero_f64 - array [1.0, 0.0, 3.0, -0.0] | Covered by scalar.slt:828 (column test with small_floats) |
| test_iszero_f32 - array [1.0, 0.0, 3.0, -0.0] | Covered by scalar.slt:828 (column test with small_floats) |
| test_iszero_scalar_f64_zero - 0.0 | iszero(0.0) in scalar.slt:816 and math.slt:116 |
| test_iszero_scalar_f64_neg_zero - -0.0 | iszero(-0.0) in scalar.slt:816 and math.slt:116 |
| test_iszero_scalar_f64_non_zero - 1.5 | iszero(10.0) returns false in scalar.slt:816, iszero(1.0) in math.slt:116 |
| test_iszero_scalar_null - null | iszero(NULL) in scalar.slt:822 and math.slt:116 |
Jefffrey
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Jan 21, 2026
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Thanks @kumarUjjawal |
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## Which issue does this PR close? <!-- We generally require a GitHub issue to be filed for all bug fixes and enhancements and this helps us generate change logs for our releases. You can link an issue to this PR using the GitHub syntax. For example `Closes apache#123` indicates that this PR will close issue apache#123. --> - Part of apache/datafusion-comet#2986. ## Rationale for this change The `iszero` function currently converts scalar inputs to arrays before processing, even for single scalar values. This adds unnecessary overhead from array allocation and conversion. Adding a scalar fast path avoids this overhead and improves performance <!-- Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed. Explaining clearly why changes are proposed helps reviewers understand your changes and offer better suggestions for fixes. --> ## What changes are included in this PR? - Added scalar fast path for `Float16`, `Float32`, and `Float64` scalar inputs - Updated tests | Type | Before | After | Speedup | |------|--------|-------|---------| | **iszero f32 scalar** | 244 ns | 62 ns | **3.9x** | | **iszero f64 scalar** | 245 ns | 62 ns | **4.0x** | <!-- There is no need to duplicate the description in the issue here but it is sometimes worth providing a summary of the individual changes in this PR. --> ## Are these changes tested? Yes <!-- We typically require tests for all PRs in order to: 1. Prevent the code from being accidentally broken by subsequent changes 2. Serve as another way to document the expected behavior of the code If tests are not included in your PR, please explain why (for example, are they covered by existing tests)? --> ## Are there any user-facing changes? No <!-- If there are user-facing changes then we may require documentation to be updated before approving the PR. --> <!-- If there are any breaking changes to public APIs, please add the `api change` label. -->
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Which issue does this PR close?
Rationale for this change
The
iszerofunction currently converts scalar inputs to arrays before processing, even for single scalar values. This adds unnecessary overhead from array allocation and conversion. Adding a scalar fast path avoids this overhead and improves performanceWhat changes are included in this PR?
Float16,Float32, andFloat64scalar inputsAre these changes tested?
Yes
Are there any user-facing changes?
No