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perf: reuse mask in truncate_list_nulls and avoid counting all true bits #22158

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Merged
rluvaton merged 3 commits into from
May 14, 2026
+8 −6
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perf: reuse mask in truncate_list_nulls and avoid counting all true bits #22158

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perf: reuse mask in `truncate_list_nulls` and avoid counting all true
rluvaton May 13, 2026
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rluvaton May 13, 2026
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rluvaton May 14, 2026
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14 changes: 8 additions & 6 deletions datafusion/common/src/utils/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,12 +31,12 @@ use arrow::array::{
cast::AsArray,
};
use arrow::array::{
ArrowPrimitiveType, Datum, GenericListArray, Int32Array, Int64Array,
ArrowPrimitiveType, BooleanArray, Datum, GenericListArray, Int32Array, Int64Array,
MutableArrayData, PrimitiveArray, make_array,
};
use arrow::array::{LargeListViewArray, ListViewArray};
use arrow::buffer::{OffsetBuffer, ScalarBuffer};
use arrow::compute::kernels::cmp::neq;
use arrow::compute::kernels::cmp::eq;
use arrow::compute::kernels::length::length;
use arrow::compute::{SortColumn, SortOptions, partition};
use arrow::datatypes::{
Expand Down Expand Up @@ -1129,6 +1129,7 @@ pub fn remove_list_null_values(array: &ArrayRef) -> Result<ArrayRef> {
}
}

/// Create a new list array where all the nulls point to empty lists
fn truncate_list_nulls<O: OffsetSizeTrait>(
list: &GenericListArray<O>,
) -> Result<GenericListArray<O>> {
Expand All @@ -1142,17 +1143,18 @@ fn truncate_list_nulls<O: OffsetSizeTrait>(
&Int64Array::new_scalar(0)
};

let not_empty = neq(&lengths, zero)?;
let null_and_non_empty = &!nulls.inner() & not_empty.values();
let (mut valid_or_empty, _nulls) = eq(&lengths, zero)?.into_parts();
valid_or_empty |= nulls.inner();
let valid_or_empty = BooleanArray::from(valid_or_empty);
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@comphead comphead May 13, 2026

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I was thinking can we optimize even more and avoid allocating BooleanArray here?

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@gstvg gstvg May 14, 2026

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BooleanArray::has_false used below I believe has no performatic BooleanBuffer equivalent: .iter().any(|v| !v) checks bit for bit (as a future improvement, the non-null branch could be moved to BooleanBuffer). But that BooleanArray::from BooleanBuffer should be cheap anyway.

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@rluvaton rluvaton May 14, 2026 •
edited
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IMO This is really premature optimization, BooleanArray allocation is super cheap

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@alamb alamb May 14, 2026

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Is the proposal to move the code from BooleanArray::has_false to BooleanBuffer::has_false upstream? That seems reasonable for what it is worth

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@rluvaton rluvaton May 14, 2026

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I would like that too, need to create a pr for that


if null_and_non_empty.count_set_bits() > 0 {
if valid_or_empty.has_false() {
let array_data = list.values().to_data();
let offsets = list.offsets();
let capacity = offsets[offsets.len() - 1] - offsets[0];
let mut mutable_array_data =
MutableArrayData::new(vec![&array_data], false, capacity.as_usize());

let valid_or_empty = nulls.inner() | &!not_empty.values();
let (valid_or_empty, _nulls) = valid_or_empty.into_parts();

for (start, end) in valid_or_empty.set_slices() {
mutable_array_data.extend(
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