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perf: optimize array_empty udf #23923

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rluvaton merged 3 commits into from
Jul 28, 2026
+14 −4
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perf: optimize array_empty udf #23923

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perf: optimize `array_empty` udf
rluvaton Jul 27, 2026
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rluvaton Jul 27, 2026
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rluvaton Jul 28, 2026
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18 changes: 14 additions & 4 deletions datafusion/functions-nested/src/empty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -122,9 +122,19 @@ fn array_empty_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
}

fn general_array_empty<O: OffsetSizeTrait>(array: &ArrayRef) -> Result<ArrayRef> {
let result = as_generic_list_array::<O>(array)?
.iter()

@rluvaton rluvaton Jul 27, 2026

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calling iter on ListArray is slow since it slice each list values which every slice recompute the null count and more

.map(|arr| arr.map(|arr| arr.is_empty()))

@rluvaton rluvaton Jul 27, 2026

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iter also return None for nulls which means that it need to read the null info while it is not needed

.collect::<BooleanArray>();

@rluvaton rluvaton Jul 27, 2026

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collect not using the from_trusted_len_iter helper which is faster

let result = as_generic_list_array::<O>(array)?;
let is_empty_iter = result.offsets().lengths().map(|n| n == 0);

@rluvaton rluvaton Jul 27, 2026

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this is faster since we only need to look at one buffer and can make it very fast
the values of the list are irrelevent

// SAFETY: this is safe since the iterator lengths is exact size and
// trusted - it maps over fixed known number of elements
let output_buffer = unsafe { BooleanArray::from_trusted_len_iter(is_empty_iter) };

let (values, _) = output_buffer.into_parts();

// Add the nulls
let result = BooleanArray::new(
values,
result.nulls().filter(|n| n.null_count() > 0).cloned(),
);

Ok(Arc::new(result))
}
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