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new 2108f20db1 feat(parquet): add all-null fast paths for level building
(#9954)
2108f20db1 is described below
commit 2108f20db1f6bc300bc6e1deacc0fca299e7feda
Author: Hippolyte Barraud <[email protected]>
AuthorDate: Thu May 14 15:22:12 2026 -0400
feat(parquet): add all-null fast paths for level building (#9954)
# Which issue does this PR close?
<!--
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enhancements and this helps us generate change logs for our releases.
You can link an issue to this PR using the GitHub syntax.
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- Spawn off from #9653
- Contributes to #9731
# Rationale for this change
<!--
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.
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See #9731
# What changes are included in this PR?
When an entire list, struct, fixed-size list, or leaf array is null,
skip per-row iteration and emit bulk uniform def/rep levels via
`extend_uniform_levels` in O(1).
# Are these changes tested?
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All tests passing + additional all null unit tests.
# Are there any user-facing changes?
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None.
Signed-off-by: Hippolyte Barraud <[email protected]>
---
parquet/src/arrow/arrow_writer/levels.rs | 200 ++++++++++++++++++++++++++++++-
1 file changed, 197 insertions(+), 3 deletions(-)
diff --git a/parquet/src/arrow/arrow_writer/levels.rs
b/parquet/src/arrow/arrow_writer/levels.rs
index 1f66de349d..73f9221376 100644
--- a/parquet/src/arrow/arrow_writer/levels.rs
+++ b/parquet/src/arrow/arrow_writer/levels.rs
@@ -311,6 +311,15 @@ impl LevelInfoBuilder {
nulls: Option<&NullBuffer>,
range: Range<usize>,
) {
+ // Fast path: entire list array is null; emit bulk null rep/def levels
+ if nulls.is_some_and(|nulls| nulls.null_count() == nulls.len()) {
+ let count = range.end - range.start;
+ child.visit_leaves(|leaf| {
+ leaf.extend_uniform_levels(ctx.def_level - 2, ctx.rep_level -
1, count);
+ });
+ return;
+ }
+
let offsets = &offsets[range.start..range.end + 1];
let write_non_null_slice =
@@ -502,15 +511,20 @@ impl LevelInfoBuilder {
range: Range<usize>,
) {
let write_null = |children: &mut [LevelInfoBuilder], range:
Range<usize>| {
+ let len = range.end - range.start;
for child in children {
child.visit_leaves(|info| {
- let len = range.end - range.start;
- info.append_def_level_run(ctx.def_level - 1, len);
- info.append_rep_level_run(ctx.rep_level, len);
+ info.extend_uniform_levels(ctx.def_level - 1,
ctx.rep_level, len);
})
}
};
+ // Fast path: entire struct array is null; emit bulk null def/rep
levels
+ if nulls.is_some_and(|nulls| nulls.null_count() == nulls.len()) {
+ write_null(children, range);
+ return;
+ }
+
let write_non_null = |children: &mut [LevelInfoBuilder], range:
Range<usize>| {
for child in children {
child.write(range.clone())
@@ -560,6 +574,15 @@ impl LevelInfoBuilder {
nulls: Option<&NullBuffer>,
range: Range<usize>,
) {
+ // Fast path: entire fixed-size list array is null
+ if nulls.is_some_and(|nulls| nulls.null_count() == nulls.len()) {
+ let count = range.end - range.start;
+ child.visit_leaves(|leaf| {
+ leaf.extend_uniform_levels(ctx.def_level - 2, ctx.rep_level -
1, count);
+ });
+ return;
+ }
+
let write_non_null = |child: &mut LevelInfoBuilder, start_idx: usize,
end_idx: usize| {
let values_start = start_idx * fixed_size;
let values_end = end_idx * fixed_size;
@@ -638,6 +661,14 @@ impl LevelInfoBuilder {
fn write_leaf(info: &mut ArrayLevels, range: Range<usize>) {
let len = range.end - range.start;
+ // Fast path: entire leaf array is null
+ if let Some(nulls) = &info.logical_nulls {
+ if !matches!(info.def_levels, LevelData::Absent) &&
nulls.null_count() == nulls.len() {
+ info.extend_uniform_levels(info.max_def_level - 1,
info.max_rep_level, len);
+ return;
+ }
+ }
+
if matches!(info.def_levels, LevelData::Absent) {
info.non_null_indices.extend(range.clone());
} else {
@@ -972,6 +1003,12 @@ impl ArrayLevels {
}
}
+ /// Bulk-emit `count` uniform def/rep levels.
+ fn extend_uniform_levels(&mut self, def_val: i16, rep_val: i16, count:
usize) {
+ self.def_levels.append_run(def_val, count);
+ self.rep_levels.append_run(rep_val, count);
+ }
+
fn append_def_level_run(&mut self, value: i16, count: usize) {
self.def_levels.append_run(value, count);
}
@@ -2442,4 +2479,161 @@ mod tests {
assert_eq!(sliced.non_null_indices, Vec::<usize>::new());
assert_eq!(sliced.array.len(), 0);
}
+
+ #[test]
+ fn test_all_null_list() {
+ // List<Int32> where every list slot is null.
+ // Schema: list (nullable) -> item (int32, nullable)
+ // Data: [null, null, null, null]
+ //
+ // Expected: max_def=3, max_rep=1, def/rep levels all 0.
+ let item_field = Arc::new(Field::new_list_field(DataType::Int32,
true));
+ let list = ListArray::new_null(item_field, 4);
+ let values = list.values().clone();
+ let field = Field::new("list", list.data_type().clone(), true);
+ let array = Arc::new(list) as ArrayRef;
+
+ let levels = calculate_array_levels(&array, &field).unwrap();
+ assert_eq!(levels.len(), 1);
+
+ let logical_nulls = values.logical_nulls();
+ let expected = ArrayLevels {
+ def_levels: LevelData::Uniform { value: 0, count: 4 },
+ rep_levels: LevelData::Uniform { value: 0, count: 4 },
+ non_null_indices: vec![],
+ max_def_level: 3,
+ max_rep_level: 1,
+ array: values,
+ logical_nulls,
+ };
+ assert_eq!(&levels[0], &expected);
+ }
+
+ #[test]
+ fn test_all_null_fixed_size_list() {
+ // FixedSizeList<Int32; 2> where every list slot is null.
+ // Schema: list (nullable) -> item (int32, nullable)
+ // Data: [null, null, null]
+ //
+ // Expected: max_def=3, max_rep=1, def/rep levels all 0.
+ let item_field = Arc::new(Field::new_list_field(DataType::Int32,
true));
+ let list = FixedSizeListArray::new_null(item_field, 2, 3);
+ let values = list.values().clone();
+ let field = Field::new("list", list.data_type().clone(), true);
+ let array = Arc::new(list) as ArrayRef;
+
+ let levels = calculate_array_levels(&array, &field).unwrap();
+ assert_eq!(levels.len(), 1);
+
+ let logical_nulls = values.logical_nulls();
+ let expected = ArrayLevels {
+ def_levels: LevelData::Uniform { value: 0, count: 3 },
+ rep_levels: LevelData::Uniform { value: 0, count: 3 },
+ non_null_indices: vec![],
+ max_def_level: 3,
+ max_rep_level: 1,
+ array: values,
+ logical_nulls,
+ };
+ assert_eq!(&levels[0], &expected);
+ }
+
+ #[test]
+ fn test_all_null_struct() {
+ // Struct<Int32> where every struct slot is null.
+ // Schema: a (struct, nullable) -> c (int32, nullable)
+ // Data: [null, null, null, null]
+ //
+ // Expected: max_def=2, def_levels all 0 (struct is null → child never
reached),
+ // leaf values are empty.
+ let c = Int32Array::from(vec![None::<i32>; 4]);
+ let leaf = Arc::new(c) as ArrayRef;
+ let c_field = Arc::new(Field::new("c", DataType::Int32, true));
+ let a = StructArray::from((vec![(c_field, leaf.clone())],
Buffer::from([0b00000000])));
+ let a_field = Field::new("a", a.data_type().clone(), true);
+ let a_array = Arc::new(a) as ArrayRef;
+
+ let levels = calculate_array_levels(&a_array, &a_field).unwrap();
+ assert_eq!(levels.len(), 1);
+
+ let expected = ArrayLevels {
+ def_levels: LevelData::Uniform { value: 0, count: 4 },
+ rep_levels: LevelData::Absent,
+ non_null_indices: vec![],
+ max_def_level: 2,
+ max_rep_level: 0,
+ array: leaf,
+ logical_nulls: Some(NullBuffer::new_null(4)),
+ };
+ assert_eq!(&levels[0], &expected);
+ }
+
+ #[test]
+ fn test_all_null_nested_struct() {
+ // Struct<Struct<Int32>> where the outer struct is entirely null.
+ // Schema: a (struct, nullable) -> b (struct, nullable) -> c (int32,
nullable)
+ // Data: [null, null, null]
+ //
+ // Expected: max_def=3, def_levels all 0.
+ let c = Int32Array::from(vec![None::<i32>; 3]);
+ let leaf = Arc::new(c) as ArrayRef;
+ let c_field = Arc::new(Field::new("c", DataType::Int32, true));
+ let b = StructArray::from((vec![(c_field, leaf.clone())],
Buffer::from([0b00000000])));
+ let b_field = Arc::new(Field::new("b", b.data_type().clone(), true));
+ let a = StructArray::from((
+ vec![(b_field, Arc::new(b) as ArrayRef)],
+ Buffer::from([0b00000000]),
+ ));
+ let a_field = Field::new("a", a.data_type().clone(), true);
+ let a_array = Arc::new(a) as ArrayRef;
+
+ let levels = calculate_array_levels(&a_array, &a_field).unwrap();
+ assert_eq!(levels.len(), 1);
+
+ let expected = ArrayLevels {
+ def_levels: LevelData::Uniform { value: 0, count: 3 },
+ rep_levels: LevelData::Absent,
+ non_null_indices: vec![],
+ max_def_level: 3,
+ max_rep_level: 0,
+ array: leaf,
+ logical_nulls: Some(NullBuffer::new_null(3)),
+ };
+ assert_eq!(&levels[0], &expected);
+ }
+
+ #[test]
+ fn test_all_null_struct_multiple_children() {
+ // Struct with two leaf children, entirely null.
+ // Schema: a (struct, nullable) -> { c1 (int32, nullable), c2 (int32,
nullable) }
+ // Data: [null, null]
+ //
+ // Both leaf columns should get uniform def_levels=0.
+ let c1 = Arc::new(Int32Array::from(vec![None::<i32>; 2])) as ArrayRef;
+ let c2 = Arc::new(Int32Array::from(vec![None::<i32>; 2])) as ArrayRef;
+ let c1_field = Arc::new(Field::new("c1", DataType::Int32, true));
+ let c2_field = Arc::new(Field::new("c2", DataType::Int32, true));
+ let a = StructArray::from((
+ vec![(c1_field, c1.clone()), (c2_field, c2.clone())],
+ Buffer::from([0b00000000]),
+ ));
+ let a_field = Field::new("a", a.data_type().clone(), true);
+ let a_array = Arc::new(a) as ArrayRef;
+
+ let levels = calculate_array_levels(&a_array, &a_field).unwrap();
+ assert_eq!(levels.len(), 2);
+
+ for (i, leaf) in [c1, c2].into_iter().enumerate() {
+ let expected = ArrayLevels {
+ def_levels: LevelData::Uniform { value: 0, count: 2 },
+ rep_levels: LevelData::Absent,
+ non_null_indices: vec![],
+ max_def_level: 2,
+ max_rep_level: 0,
+ array: leaf,
+ logical_nulls: Some(NullBuffer::new_null(2)),
+ };
+ assert_eq!(&levels[i], &expected, "leaf {i} mismatch");
+ }
+ }
}
