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GH-43010: [C++][Compute] Support view arrays in selection kernels #50164

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GH-43010: [C++][Compute] Support view arrays in selection kernels #50164

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4 changes: 1 addition & 3 deletions cpp/src/arrow/compute/kernels/scalar_cast_internal.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -280,10 +280,8 @@ void AddZeroCopyCast(Type::type in_type_id, InputType in_type, OutputType out_ty
}

static bool CanCastFromDictionary(Type::type type_id) {
/// TODO(GH-43010): add is_binary_view_like() here once array_take
/// can handle string-views
return (is_primitive(type_id) || is_base_binary_like(type_id) ||
is_fixed_size_binary(type_id));
is_binary_view_like(type_id) || is_fixed_size_binary(type_id));
}

void AddCommonCasts(Type::type out_type_id, OutputType out_ty, CastFunction* func) {
Expand Down
47 changes: 47 additions & 0 deletions cpp/src/arrow/compute/kernels/scalar_cast_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -4368,6 +4368,53 @@ TEST(Cast, FromDictionary) {
}
}

TEST(Cast, DictionaryDecodeFromViewDictionary) {
for (const auto& value_type : {binary_view(), utf8_view()}) {
ARROW_SCOPED_TRACE(value_type->ToString());
auto dict_values = ArrayFromJSON(
value_type, R"(["alpha", "long-value-over-inline-limit", "omega"])");
auto indices = ArrayFromJSON(int8(), "[0, 1, null, 2, 1]");
ASSERT_OK_AND_ASSIGN(auto dict_arr,
DictionaryArray::FromArrays(dictionary(int8(), value_type),
indices, dict_values));
auto expected = ArrayFromJSON(
value_type,
R"(["alpha", "long-value-over-inline-limit", null, "omega", "long-value-over-inline-limit"])");

ASSERT_OK_AND_ASSIGN(Datum decoded, CallFunction("dictionary_decode", {dict_arr}));
ValidateOutput(decoded);
AssertArraysEqual(*expected, *decoded.make_array(), /*verbose=*/true);
CheckCast(dict_arr, expected);

auto chunked_dict = std::make_shared<ChunkedArray>(
ArrayVector{dict_arr->Slice(0, 2), dict_arr->Slice(2, 3)});
ASSERT_OK_AND_ASSIGN(Datum decoded_chunked,
CallFunction("dictionary_decode", {chunked_dict}));
ValidateOutput(decoded_chunked);
AssertChunkedEqual(
*ChunkedArrayFromJSON(value_type,
{R"(["alpha", "long-value-over-inline-limit"])",
R"([null, "omega", "long-value-over-inline-limit"])"}),
*decoded_chunked.chunked_array());

auto dict_values_with_null = ArrayFromJSON(value_type, R"(["alpha", null, "omega"])");
auto indices_with_null_source = ArrayFromJSON(int8(), "[0, 1, null, 2]");
ASSERT_OK_AND_ASSIGN(
auto dict_arr_with_null,
DictionaryArray::FromArrays(dictionary(int8(), value_type),
indices_with_null_source, dict_values_with_null));
auto expected_with_null_source =
ArrayFromJSON(value_type, R"(["alpha", null, null, "omega"])");

ASSERT_OK_AND_ASSIGN(Datum decoded_with_null_source,
CallFunction("dictionary_decode", {dict_arr_with_null}));
ValidateOutput(decoded_with_null_source);
AssertArraysEqual(*expected_with_null_source, *decoded_with_null_source.make_array(),
/*verbose=*/true);
CheckCast(dict_arr_with_null, expected_with_null_source);
}
}

std::shared_ptr<Array> SmallintArrayFromJSON(const std::string& json_data) {
auto arr = ArrayFromJSON(int16(), json_data);
auto ext_data = arr->data()->Copy();
Expand Down
9 changes: 9 additions & 0 deletions cpp/src/arrow/compute/kernels/vector_selection_filter_internal.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -919,6 +919,11 @@ Status SparseUnionFilterExec(KernelContext* ctx, const ExecSpan& batch, ExecResu
return FilterWithTakeExec(SparseUnionTakeExec, ctx, batch, out);
}

Status VarBinaryViewFilterExec(KernelContext* ctx, const ExecSpan& batch,
ExecResult* out) {
return FilterWithTakeExec(VarBinaryViewTakeExec, ctx, batch, out);
}

// ----------------------------------------------------------------------
// Implement Filter metafunction

Expand Down Expand Up @@ -1094,6 +1099,8 @@ void PopulateFilterKernels(std::vector<SelectionKernelData>* out) {
{InputType(match::Primitive()), plain_filter, PrimitiveFilterExec},
{InputType(match::BinaryLike()), plain_filter, BinaryFilterExec},
{InputType(match::LargeBinaryLike()), plain_filter, BinaryFilterExec},
{InputType(Type::BINARY_VIEW), plain_filter, VarBinaryViewFilterExec},
{InputType(Type::STRING_VIEW), plain_filter, VarBinaryViewFilterExec},
{InputType(null()), plain_filter, NullFilterExec},
{InputType(Type::FIXED_SIZE_BINARY), plain_filter, PrimitiveFilterExec},
{InputType(Type::DECIMAL32), plain_filter, PrimitiveFilterExec},
Expand All @@ -1116,6 +1123,8 @@ void PopulateFilterKernels(std::vector<SelectionKernelData>* out) {
{InputType(match::Primitive()), ree_filter, PrimitiveFilterExec},
{InputType(match::BinaryLike()), ree_filter, BinaryFilterExec},
{InputType(match::LargeBinaryLike()), ree_filter, BinaryFilterExec},
{InputType(Type::BINARY_VIEW), ree_filter, VarBinaryViewFilterExec},
{InputType(Type::STRING_VIEW), ree_filter, VarBinaryViewFilterExec},
{InputType(null()), ree_filter, NullFilterExec},
{InputType(Type::FIXED_SIZE_BINARY), ree_filter, PrimitiveFilterExec},
{InputType(Type::DECIMAL32), ree_filter, PrimitiveFilterExec},
Expand Down
1 change: 1 addition & 0 deletions cpp/src/arrow/compute/kernels/vector_selection_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,7 @@ Status MapFilterExec(KernelContext*, const ExecSpan&, ExecResult*);

Status VarBinaryTakeExec(KernelContext*, const ExecSpan&, ExecResult*);
Status LargeVarBinaryTakeExec(KernelContext*, const ExecSpan&, ExecResult*);
Status VarBinaryViewTakeExec(KernelContext*, const ExecSpan&, ExecResult*);
Status FixedWidthTakeExec(KernelContext*, const ExecSpan&, ExecResult*);
Status ListTakeExec(KernelContext*, const ExecSpan&, ExecResult*);
Status LargeListTakeExec(KernelContext*, const ExecSpan&, ExecResult*);
Expand Down
120 changes: 120 additions & 0 deletions cpp/src/arrow/compute/kernels/vector_selection_take_internal.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@

#include "arrow/array/builder_primitive.h"
#include "arrow/array/concatenate.h"
#include "arrow/buffer.h"
#include "arrow/buffer_builder.h"
#include "arrow/chunked_array.h"
#include "arrow/compute/api_vector.h"
Expand Down Expand Up @@ -488,6 +489,123 @@ Status FixedWidthTakeExec(KernelContext* ctx, const ExecSpan& batch, ExecResult*

namespace {

template <typename IndexCType>
Status VarBinaryViewTakeTyped(const ArraySpan& values, const ArraySpan& indices,
BinaryViewType::c_type* out_views, uint8_t* out_validity,
int64_t* valid_count) {
const auto* source_views = values.GetValues<BinaryViewType::c_type>(1);
const auto* index_values = indices.GetValues<IndexCType>(1);

const bool values_may_have_nulls = values.MayHaveNulls();
const bool indices_may_have_nulls = indices.MayHaveNulls();

if (!values_may_have_nulls && !indices_may_have_nulls) {
for (int64_t out_i = 0; out_i < indices.length; ++out_i) {
out_views[out_i] = source_views[static_cast<int64_t>(index_values[out_i])];
}
*valid_count = indices.length;
return Status::OK();
}

for (int64_t out_i = 0; out_i < indices.length; ++out_i) {
if (indices_may_have_nulls &&
!bit_util::GetBit(indices.buffers[0].data, indices.offset + out_i)) {
Comment on lines +511 to +512

@pitrou pitrou Jun 15, 2026

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I think you can use VisitTwoBitBlocksVoid which will be more efficient than individual calls to GetBit for each item.

continue;
}

const int64_t source_i = static_cast<int64_t>(index_values[out_i]);
const bool source_valid =
!values_may_have_nulls ||
bit_util::GetBit(values.buffers[0].data, values.offset + source_i);
if (!source_valid) {
continue;
}

out_views[out_i] = source_views[source_i];
if (out_validity != nullptr) {
bit_util::SetBit(out_validity, out_i);
}
Comment on lines +525 to +527

@pitrou pitrou Jun 15, 2026 •
edited
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OptionalBitmapAnd would probably be much more efficient than settings output validity bits individually.

++(*valid_count);
}

return Status::OK();
}

Status VarBinaryViewTakeDispatch(const ArraySpan& values, const ArraySpan& indices,
BinaryViewType::c_type* out_views, uint8_t* out_validity,
int64_t* valid_count) {
switch (indices.type->byte_width()) {
case 1:
return VarBinaryViewTakeTyped<uint8_t>(values, indices, out_views, out_validity,
valid_count);
case 2:
return VarBinaryViewTakeTyped<uint16_t>(values, indices, out_views, out_validity,
valid_count);
case 4:
return VarBinaryViewTakeTyped<uint32_t>(values, indices, out_views, out_validity,
valid_count);
default:
DCHECK_EQ(indices.type->byte_width(), 8);
return VarBinaryViewTakeTyped<uint64_t>(values, indices, out_views, out_validity,
valid_count);
}
}

} // namespace

Status VarBinaryViewTakeExec(KernelContext* ctx, const ExecSpan& batch, ExecResult* out) {
const ArraySpan& values = batch[0].array;
const ArraySpan& indices = batch[1].array;

if (TakeState::Get(ctx).boundscheck) {
RETURN_NOT_OK(CheckIndexBounds(indices, values.length));
}

const int64_t out_length = indices.length;
const bool may_have_nulls = values.MayHaveNulls() || indices.MayHaveNulls();
const auto data_buffers = values.GetVariadicBuffers();

ARROW_ASSIGN_OR_RAISE(
auto views_buf,
AllocateBuffer(out_length * static_cast<int64_t>(sizeof(BinaryViewType::c_type)),
ctx->memory_pool()));
auto* out_views = reinterpret_cast<BinaryViewType::c_type*>(views_buf->mutable_data());
if (may_have_nulls && views_buf->size() > 0) {
std::memset(out_views, 0, views_buf->size());
}

std::shared_ptr<Buffer> validity_buf;
uint8_t* out_validity = nullptr;
if (may_have_nulls) {
ARROW_ASSIGN_OR_RAISE(validity_buf,
AllocateEmptyBitmap(out_length, ctx->memory_pool()));
if (validity_buf->size() > 0) {
std::memset(validity_buf->mutable_data(), 0, validity_buf->size());
}
Comment on lines +582 to +584

@pitrou pitrou Jun 15, 2026

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AllocateEmptyBitmap should ensure that the bitmap is already zero-filled, IIRC.

out_validity = validity_buf->mutable_data();
}

int64_t valid_count = 0;
RETURN_NOT_OK(
VarBinaryViewTakeDispatch(values, indices, out_views, out_validity, &valid_count));

const int64_t null_count = out_length - valid_count;
BufferVector buffers;
buffers.reserve(2 + data_buffers.size());
buffers.push_back(null_count == 0 ? nullptr : std::move(validity_buf));
buffers.push_back(std::move(views_buf));

for (const auto& data_buffer : data_buffers) {
buffers.push_back(data_buffer);
}
Comment on lines +598 to +600

@pitrou pitrou Jun 15, 2026

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This is going to keep alive all data buffers from the input, but it would be nice to only keep alive those that are actually used by the output.

Depending on the outcome from #50172 we may replace the unused buffers with NULL slots, or with zero-sized buffers (or we can remap the buffer indices, which is going to be more costly).


out->value = ArrayData::Make(values.type->GetSharedPtr(), out_length,
std::move(buffers), null_count, /*offset=*/0);
return Status::OK();
}

namespace {

// ----------------------------------------------------------------------
// Null take

Expand Down Expand Up @@ -740,6 +858,8 @@ void PopulateTakeKernels(std::vector<SelectionKernelData>* out) {
{InputType(match::Primitive()), take_indices, FixedWidthTakeExec},
{InputType(match::BinaryLike()), take_indices, VarBinaryTakeExec},
{InputType(match::LargeBinaryLike()), take_indices, LargeVarBinaryTakeExec},
{InputType(Type::BINARY_VIEW), take_indices, VarBinaryViewTakeExec},
{InputType(Type::STRING_VIEW), take_indices, VarBinaryViewTakeExec},
{InputType(match::FixedSizeBinaryLike()), take_indices, FixedWidthTakeExec},
{InputType(null()), take_indices, NullTakeExec},
{InputType(Type::DICTIONARY), take_indices, DictionaryTake},
Expand Down
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