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Fix IPC roundtripping dicts nested in ListViews #9126

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Merged
alamb merged 1 commit into from
Jan 10, 2026
Merged

Fix IPC roundtripping dicts nested in ListViews #9126

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136 changes: 136 additions & 0 deletions arrow-ipc/src/writer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -296,6 +296,30 @@ impl IpcDataGenerator {
compression_context,
)?;
}
DataType::ListView(field) => {
let list = column.as_list_view::<i32>();
self.encode_dictionaries(
field,
list.values(),
encoded_dictionaries,
dictionary_tracker,
write_options,
dict_id,
compression_context,
)?;
}
DataType::LargeListView(field) => {
let list = column.as_list_view::<i64>();
self.encode_dictionaries(
field,
list.values(),
encoded_dictionaries,
dictionary_tracker,
write_options,
dict_id,
compression_context,
)?;
}
DataType::FixedSizeList(field, _) => {
let list = column
.as_any()
Expand Down Expand Up @@ -3402,6 +3426,118 @@ mod tests {
assert_eq!(in_batch, out_batch);
}

fn test_roundtrip_list_view_of_dict_impl<OffsetSize: OffsetSizeTrait, U: ArrowNativeType>(

@alamb alamb Jan 9, 2026

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I verified these tests fail without the provided code fix

failures:

---- writer::tests::test_roundtrip_large_list_view_of_dict stdout ----

thread 'writer::tests::test_roundtrip_large_list_view_of_dict' (26537286) panicked at arrow-ipc/src/writer.rs:2145:32:
called `Result::unwrap()` on an `Err` value: ParseError("Cannot find a dictionary batch with dict id: 0")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- writer::tests::test_roundtrip_list_view_of_dict stdout ----

thread 'writer::tests::test_roundtrip_list_view_of_dict' (26537289) panicked at arrow-ipc/src/writer.rs:2145:32:
called `Result::unwrap()` on an `Err` value: ParseError("Cannot find a dictionary batch with dict id: 0")

---- writer::tests::test_roundtrip_sliced_list_view_of_dict stdout ----

thread 'writer::tests::test_roundtrip_sliced_list_view_of_dict' (26537290) panicked at arrow-ipc/src/writer.rs:2145:32:
called `Result::unwrap()` on an `Err` value: ParseError("Cannot find a dictionary batch with dict id: 0")


failures:
    writer::tests::test_roundtrip_large_list_view_of_dict
    writer::tests::test_roundtrip_list_view_of_dict
    writer::tests::test_roundtrip_sliced_list_view_of_dict

test result: FAILED. 92 passed; 3 failed; 0 ignored; 0 measured; 0 filtered out; finished in 4.73s

list_data_type: DataType,
offsets: &[U; 5],
sizes: &[U; 4],
) {
let values = StringArray::from(vec![Some("alpha"), None, Some("beta"), Some("gamma")]);
let keys = Int32Array::from_iter_values([0, 0, 1, 2, 3, 0, 2]);
let dict_array = DictionaryArray::new(keys, Arc::new(values));
let dict_data = dict_array.to_data();

let value_offsets = Buffer::from_slice_ref(offsets);
let value_sizes = Buffer::from_slice_ref(sizes);

let list_data = ArrayData::builder(list_data_type)
.len(4)
.add_buffer(value_offsets)
.add_buffer(value_sizes)
.add_child_data(dict_data)
.build()
.unwrap();
let list_view_array = GenericListViewArray::<OffsetSize>::from(list_data);

let schema = Arc::new(Schema::new(vec![Field::new(
"f1",
list_view_array.data_type().clone(),
false,
)]));
let input_batch = RecordBatch::try_new(schema, vec![Arc::new(list_view_array)]).unwrap();

let output_batch = deserialize_file(serialize_file(&input_batch));
assert_eq!(input_batch, output_batch);

let output_batch = deserialize_stream(serialize_stream(&input_batch));
assert_eq!(input_batch, output_batch);
}

#[test]
fn test_roundtrip_list_view_of_dict() {
#[allow(deprecated)]
let list_data_type = DataType::ListView(Arc::new(Field::new_dict(
"item",
DataType::Dictionary(Box::new(DataType::Int32), Box::new(DataType::Utf8)),
true,
1,
false,
)));
let offsets: &[i32; 5] = &[0, 2, 4, 4, 7];
let sizes: &[i32; 4] = &[2, 2, 0, 3];
test_roundtrip_list_view_of_dict_impl::<i32, i32>(list_data_type, offsets, sizes);
}

#[test]
fn test_roundtrip_large_list_view_of_dict() {
#[allow(deprecated)]
let list_data_type = DataType::LargeListView(Arc::new(Field::new_dict(
"item",
DataType::Dictionary(Box::new(DataType::Int32), Box::new(DataType::Utf8)),
true,
2,
false,
)));
let offsets: &[i64; 5] = &[0, 2, 4, 4, 7];
let sizes: &[i64; 4] = &[2, 2, 0, 3];
test_roundtrip_list_view_of_dict_impl::<i64, i64>(list_data_type, offsets, sizes);
}

#[test]
fn test_roundtrip_sliced_list_view_of_dict() {
#[allow(deprecated)]
let list_data_type = DataType::ListView(Arc::new(Field::new_dict(
"item",
DataType::Dictionary(Box::new(DataType::Int32), Box::new(DataType::Utf8)),
true,
3,
false,
)));

let values = StringArray::from(vec![Some("alpha"), None, Some("beta"), Some("gamma")]);
let keys = Int32Array::from_iter_values([0, 0, 1, 2, 3, 0, 2, 1, 0, 3, 2, 1]);
let dict_array = DictionaryArray::new(keys, Arc::new(values));
let dict_data = dict_array.to_data();

let offsets: &[i32; 7] = &[0, 2, 4, 4, 7, 9, 12];
let sizes: &[i32; 6] = &[2, 2, 0, 3, 2, 3];
let value_offsets = Buffer::from_slice_ref(offsets);
let value_sizes = Buffer::from_slice_ref(sizes);

let list_data = ArrayData::builder(list_data_type)
.len(6)
.add_buffer(value_offsets)
.add_buffer(value_sizes)
.add_child_data(dict_data)
.build()
.unwrap();
let list_view_array = GenericListViewArray::<i32>::from(list_data);

let schema = Arc::new(Schema::new(vec![Field::new(
"f1",
list_view_array.data_type().clone(),
false,
)]));
let input_batch = RecordBatch::try_new(schema, vec![Arc::new(list_view_array)]).unwrap();

let sliced_batch = input_batch.slice(1, 4);

let output_batch = deserialize_file(serialize_file(&sliced_batch));
assert_eq!(sliced_batch, output_batch);

let output_batch = deserialize_stream(serialize_stream(&sliced_batch));
assert_eq!(sliced_batch, output_batch);
}

#[test]
fn test_decimal128_alignment16_is_sufficient() {
const IPC_ALIGNMENT: usize = 16;
Expand Down
2 changes: 2 additions & 0 deletions arrow-schema/src/field.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -718,6 +718,8 @@ impl Field {
DataType::Union(fields, _) => fields.iter().flat_map(|(_, f)| f.fields()).collect(),
DataType::List(field)
| DataType::LargeList(field)
| DataType::ListView(field)
| DataType::LargeListView(field)
| DataType::FixedSizeList(field, _)
| DataType::Map(field, _) => field.fields(),
DataType::Dictionary(_, value_field) => Field::_fields(value_field.as_ref()),
Expand Down
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