zanmato1984 commented on code in PR #45001:
URL: https://github.com/apache/arrow/pull/45001#discussion_r2224858452
##########
docs/source/cpp/compute.rst:
##########
@@ -1271,6 +1271,26 @@ Containment tests
* \(8) Output is true iff :member:`MatchSubstringOptions::pattern`
matches the corresponding input element at any position.
+
+Hash Functions
+~~~~~~~~~~~~~~
+
+Not to be confused with the "group by" functions, Hash functions produce an
array of hash
+values corresponding to the length of the input. Currently, these functions
take a single
+array as input.
+
++---------------+-------+-------------+-------------+---------------+-------+
+| Function name | Arity | Input types | Output type | Options class | Notes |
++===============+=======+=============+=============+===============+=======+
+| hash32 | Unary | Any | UInt32 | | \(1) |
++---------------+-------+-------------+-------------+---------------+-------+
+| hash64 | Unary | Any | UInt64 | | \(1) |
++---------------+-------+-------------+-------------+---------------+-------+
+
+* \(1) The implementation doesn't guarantee hash stability across different
versions of
Review Comment:
Shall we also mention that they don't emit `null`s even for `null` values.
##########
cpp/src/arrow/compute/api_scalar.h:
##########
@@ -1786,5 +1786,42 @@ ARROW_EXPORT Result<Datum> NanosecondsBetween(const
Datum& left, const Datum& ri
/// \note API not yet finalized
ARROW_EXPORT Result<Datum> MapLookup(const Datum& map, MapLookupOptions
options,
ExecContext* ctx = NULLPTR);
+
+/// \brief Construct a hash value for each row of the input.
+///
+/// The result is an Array of length equal to the length of the input;
however, the output
+/// shall be a UInt32Array, with each element being a hash constructed from
each row of
+/// the input. If the input Array is a NestedArray, this means that each
"attribute" or
+/// "field" of the input NestedArray corresponding to the same "row" will
collectively
+/// produce a single uint32_t hash. At the moment, this function does not take
options,
+/// though these may be added in the future.
+///
+/// \param[in] input_array input data to hash
+/// \param[in] ctx function execution context, optional
+/// \return elementwise hash values
+///
+/// \since 21.0.0
+/// \note API not yet finalized
+ARROW_EXPORT
+Result<Datum> Hash32(const Datum& input_array, ExecContext* ctx = NULLPTR);
+
+/// \brief Construct a hash value for each row of the input.
+///
+/// The result is an Array of length equal to the length of the input;
however, the output
+/// shall be a UInt64Array, with each element being a hash constructed from
each row of
+/// the input. If the input Array is a NestedArray, this means that each
"attribute" or
+/// "field" of the input NestedArray corresponding to the same "row" will
collectively
+/// produce a single uint64_t hash. At the moment, this function does not take
options,
+/// though these may be added in the future.
+///
+/// \param[in] input_array input data to hash
+/// \param[in] ctx function execution context, optional
+/// \return elementwise hash values
+///
+/// \since 21.0.0
Review Comment:
```suggestion
/// \since 22.0.0
```
##########
docs/source/cpp/compute.rst:
##########
@@ -1271,6 +1271,26 @@ Containment tests
* \(8) Output is true iff :member:`MatchSubstringOptions::pattern`
matches the corresponding input element at any position.
+
+Hash Functions
+~~~~~~~~~~~~~~
+
+Not to be confused with the "group by" functions, Hash functions produce an
array of hash
+values corresponding to the length of the input. Currently, these functions
take a single
+array as input.
+
++---------------+-------+-------------+-------------+---------------+-------+
+| Function name | Arity | Input types | Output type | Options class | Notes |
++===============+=======+=============+=============+===============+=======+
+| hash32 | Unary | Any | UInt32 | | \(1) |
++---------------+-------+-------------+-------------+---------------+-------+
+| hash64 | Unary | Any | UInt64 | | \(1) |
++---------------+-------+-------------+-------------+---------------+-------+
+
+* \(1) The implementation doesn't guarantee hash stability across different
versions of
+ the library. Union-, view- and run end encoded types are not supported
yet.
Review Comment:
```suggestion
the library. Union, view and run end encoded types are not supported
yet.
```
##########
cpp/src/arrow/compute/key_hash_benchmark.cc:
##########
@@ -0,0 +1,125 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <algorithm>
+#include <cstdint>
+#include <limits>
+#include <random>
+#include <string>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+
+#include "arrow/testing/gtest_util.h"
+#include "arrow/testing/random.h"
+#include "arrow/util/hashing.h"
+
+#include "arrow/array/builder_primitive.h"
+#include "arrow/compute/key_hash_internal.h"
+#include "arrow/compute/util_internal.h"
+
+namespace arrow {
+namespace internal {
+
+namespace {
+// copied from scalar_string_benchmark
+constexpr auto kSeed = 0x94378165;
+
+static random::RandomArrayGenerator hashing_rng(kSeed);
+} // namespace
+
+static void KeyHashIntegers32(benchmark::State& state) { // NOLINT non-const
reference
+ auto test_vals = hashing_rng.Int32(10000, 0,
std::numeric_limits<int32_t>::max());
+
+ // initialize the stack allocator
+ util::TempVectorStack stack_memallocator;
+ ASSERT_OK(
+ stack_memallocator.Init(compute::default_exec_context()->memory_pool(),
+ 3 * sizeof(int32_t) *
util::MiniBatch::kMiniBatchLength));
+
+ // prepare the execution context for Hashing32
+ compute::LightContext hash_ctx;
+ hash_ctx.hardware_flags =
compute::default_exec_context()->cpu_info()->hardware_flags();
+ hash_ctx.stack = &stack_memallocator;
+
+ // allocate memory for results
+ ASSERT_OK_AND_ASSIGN(std::unique_ptr<Buffer> hash_buffer,
+ AllocateBuffer(test_vals->length() * sizeof(int32_t)));
+
+ // run the benchmark
+ while (state.KeepRunning()) {
+ // Prepare input data structure for propagation to hash function
+ ASSERT_OK_AND_ASSIGN(
+ compute::KeyColumnArray input_keycol,
+ compute::ColumnArrayFromArrayData(test_vals->data(), 0,
test_vals->length()));
+
+ compute::Hashing32::HashMultiColumn(
+ {input_keycol}, &hash_ctx,
+ reinterpret_cast<uint32_t*>(hash_buffer->mutable_data()));
+
+ // benchmark::DoNotOptimize(hash_buffer);
Review Comment:
```suggestion
```
##########
cpp/src/arrow/compute/kernels/scalar_hash.cc:
##########
@@ -0,0 +1,240 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <algorithm>
+
+#include "arrow/array/array_base.h"
+#include "arrow/array/builder_primitive.h"
+#include "arrow/compute/kernels/common_internal.h"
+#include "arrow/compute/key_hash_internal.h"
+#include "arrow/compute/light_array_internal.h"
+#include "arrow/compute/util.h"
+#include "arrow/result.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+
+// Define symbols visible within `arrow::compute::internal` in this file;
+// these symbols are not visible outside of this file.
+namespace {
+
+// ------------------------------
+// Kernel implementations
+// It is expected that HashArrowType is either UInt32Type or UInt64Type
(default)
+
+template <typename ArrowType, typename Hasher>
+struct FastHashScalar {
+ using c_type = typename ArrowType::c_type;
+
+ static Result<KeyColumnArray> ToColumnArray(
+ const ArraySpan& array, LightContext* ctx,
+ const uint8_t* list_values_buffer = nullptr) {
+ KeyColumnMetadata metadata;
+ const uint8_t* validity_buffer = nullptr;
+ const uint8_t* fixed_length_buffer = nullptr;
+ const uint8_t* var_length_buffer = nullptr;
+
+ if (array.GetBuffer(0) != nullptr) {
+ validity_buffer = array.GetBuffer(0)->data();
+ }
+ if (array.GetBuffer(1) != nullptr) {
+ fixed_length_buffer = array.GetBuffer(1)->data();
+ }
+
+ auto type = array.type;
+ auto type_id = type->id();
+ if (type_id == Type::NA) {
+ metadata = KeyColumnMetadata(true, 0, true);
+ } else if (type_id == Type::BOOL) {
+ metadata = KeyColumnMetadata(true, 0);
+ } else if (is_fixed_width(type_id)) {
+ metadata = KeyColumnMetadata(true, type->bit_width() / 8);
+ } else if (is_binary_like(type_id)) {
+ metadata = KeyColumnMetadata(false, sizeof(uint32_t));
+ var_length_buffer = array.GetBuffer(2)->data();
+ } else if (is_large_binary_like(type_id)) {
+ metadata = KeyColumnMetadata(false, sizeof(uint64_t));
+ var_length_buffer = array.GetBuffer(2)->data();
+ } else if (type_id == Type::MAP) {
+ metadata = KeyColumnMetadata(false, sizeof(uint32_t));
+ var_length_buffer = list_values_buffer;
+ } else if (type_id == Type::LIST) {
+ metadata = KeyColumnMetadata(false, sizeof(uint32_t));
+ var_length_buffer = list_values_buffer;
+ } else if (type_id == Type::LARGE_LIST) {
+ metadata = KeyColumnMetadata(false, sizeof(uint64_t));
+ var_length_buffer = list_values_buffer;
+ } else if (type_id == Type::FIXED_SIZE_LIST) {
+ auto list_type = checked_cast<const FixedSizeListType*>(type);
+ metadata = KeyColumnMetadata(true, list_type->list_size());
+ fixed_length_buffer = list_values_buffer;
+ } else {
+ return Status::TypeError("Unsupported column data type ", type->name(),
+ " used with hash32/hash64 compute kernel");
+ }
+
+ return KeyColumnArray(metadata, array.length, validity_buffer,
fixed_length_buffer,
+ var_length_buffer);
+ }
+
+ static Result<std::shared_ptr<ArrayData>> HashChild(const ArraySpan& array,
+ const ArraySpan& child,
+ LightContext* hash_ctx,
+ MemoryPool* memory_pool)
{
+ auto arrow_type = TypeTraits<ArrowType>::type_singleton();
+ auto buffer_size = child.length * sizeof(c_type);
+ ARROW_ASSIGN_OR_RAISE(auto buffer, AllocateBuffer(buffer_size,
memory_pool));
+ ARROW_RETURN_NOT_OK(
+ HashArray(child, hash_ctx, memory_pool,
buffer->mutable_data_as<c_type>()));
+ return ArrayData::Make(arrow_type, child.length,
+ {array.GetBuffer(0), std::move(buffer)},
array.null_count);
+ }
+
+ static Status HashArray(const ArraySpan& array, LightContext* hash_ctx,
+ MemoryPool* memory_pool, c_type* out) {
+ // KeyColumnArray objects are being passed to the hashing utility
+ KeyColumnArray column;
+ std::vector<KeyColumnArray> columns(1);
+
+ auto type_id = array.type->id();
+ if (type_id == Type::EXTENSION) {
+ auto extension_type = checked_cast<const ExtensionType*>(array.type);
+ auto storage_array = array;
+ storage_array.type = extension_type->storage_type().get();
+ return HashArray(storage_array, hash_ctx, memory_pool, out);
+ }
+
+ if (type_id == Type::STRUCT) {
+ std::vector<std::shared_ptr<ArrayData>>
child_hashes(array.child_data.size());
+ columns.resize(array.child_data.size());
+ for (size_t i = 0; i < array.child_data.size(); i++) {
+ auto child = array.child_data[i];
+ if (is_nested(child.type->id())) {
+ ARROW_ASSIGN_OR_RAISE(child_hashes[i],
+ HashChild(array, child, hash_ctx,
memory_pool));
+ ARROW_ASSIGN_OR_RAISE(column, ToColumnArray(*child_hashes[i],
hash_ctx));
+ } else {
+ ARROW_ASSIGN_OR_RAISE(column, ToColumnArray(child, hash_ctx));
+ }
+ columns[i] = column.Slice(array.offset, array.length);
+ }
+ Hasher::HashMultiColumn(columns, hash_ctx, out);
+ } else if (is_list_like(type_id)) {
+ auto values = array.child_data[0];
+ ARROW_ASSIGN_OR_RAISE(auto value_hashes,
+ HashChild(array, values, hash_ctx, memory_pool));
+ ARROW_ASSIGN_OR_RAISE(
+ column, ToColumnArray(array, hash_ctx,
value_hashes->buffers[1]->data()));
Review Comment:
Is it possible to make a copy of the `array`, and set `array_copy.buffers[2]
= value_hashes->buffers[1]->data()`? This way, function `ToColumnArray` won't
need the extra `list_values_buffer` parameter.
##########
cpp/src/arrow/compute/key_hash_benchmark.cc:
##########
@@ -0,0 +1,125 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <algorithm>
+#include <cstdint>
+#include <limits>
+#include <random>
+#include <string>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+
+#include "arrow/testing/gtest_util.h"
+#include "arrow/testing/random.h"
+#include "arrow/util/hashing.h"
+
+#include "arrow/array/builder_primitive.h"
+#include "arrow/compute/key_hash_internal.h"
+#include "arrow/compute/util_internal.h"
+
+namespace arrow {
+namespace internal {
+
+namespace {
+// copied from scalar_string_benchmark
+constexpr auto kSeed = 0x94378165;
+
+static random::RandomArrayGenerator hashing_rng(kSeed);
+} // namespace
+
+static void KeyHashIntegers32(benchmark::State& state) { // NOLINT non-const
reference
+ auto test_vals = hashing_rng.Int32(10000, 0,
std::numeric_limits<int32_t>::max());
+
+ // initialize the stack allocator
+ util::TempVectorStack stack_memallocator;
+ ASSERT_OK(
+ stack_memallocator.Init(compute::default_exec_context()->memory_pool(),
+ 3 * sizeof(int32_t) *
util::MiniBatch::kMiniBatchLength));
+
+ // prepare the execution context for Hashing32
+ compute::LightContext hash_ctx;
+ hash_ctx.hardware_flags =
compute::default_exec_context()->cpu_info()->hardware_flags();
+ hash_ctx.stack = &stack_memallocator;
+
+ // allocate memory for results
+ ASSERT_OK_AND_ASSIGN(std::unique_ptr<Buffer> hash_buffer,
+ AllocateBuffer(test_vals->length() * sizeof(int32_t)));
+
+ // run the benchmark
+ while (state.KeepRunning()) {
+ // Prepare input data structure for propagation to hash function
+ ASSERT_OK_AND_ASSIGN(
+ compute::KeyColumnArray input_keycol,
+ compute::ColumnArrayFromArrayData(test_vals->data(), 0,
test_vals->length()));
+
+ compute::Hashing32::HashMultiColumn(
+ {input_keycol}, &hash_ctx,
+ reinterpret_cast<uint32_t*>(hash_buffer->mutable_data()));
+
+ // benchmark::DoNotOptimize(hash_buffer);
Review Comment:
Useless?
##########
cpp/src/arrow/compute/kernels/scalar_hash.cc:
##########
@@ -0,0 +1,240 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <algorithm>
+
+#include "arrow/array/array_base.h"
+#include "arrow/array/builder_primitive.h"
+#include "arrow/compute/kernels/common_internal.h"
+#include "arrow/compute/key_hash_internal.h"
+#include "arrow/compute/light_array_internal.h"
+#include "arrow/compute/util.h"
+#include "arrow/result.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+
+// Define symbols visible within `arrow::compute::internal` in this file;
+// these symbols are not visible outside of this file.
+namespace {
+
+// ------------------------------
+// Kernel implementations
+// It is expected that HashArrowType is either UInt32Type or UInt64Type
(default)
+
+template <typename ArrowType, typename Hasher>
+struct FastHashScalar {
+ using c_type = typename ArrowType::c_type;
+
+ static Result<KeyColumnArray> ToColumnArray(
+ const ArraySpan& array, LightContext* ctx,
+ const uint8_t* list_values_buffer = nullptr) {
Review Comment:
```suggestion
const ArraySpan& array, const uint8_t* list_values_buffer = nullptr) {
```
##########
cpp/src/arrow/compute/kernels/scalar_hash.cc:
##########
@@ -0,0 +1,240 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <algorithm>
+
+#include "arrow/array/array_base.h"
+#include "arrow/array/builder_primitive.h"
+#include "arrow/compute/kernels/common_internal.h"
+#include "arrow/compute/key_hash_internal.h"
+#include "arrow/compute/light_array_internal.h"
+#include "arrow/compute/util.h"
+#include "arrow/result.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+
+// Define symbols visible within `arrow::compute::internal` in this file;
+// these symbols are not visible outside of this file.
+namespace {
+
+// ------------------------------
+// Kernel implementations
+// It is expected that HashArrowType is either UInt32Type or UInt64Type
(default)
+
+template <typename ArrowType, typename Hasher>
+struct FastHashScalar {
+ using c_type = typename ArrowType::c_type;
+
+ static Result<KeyColumnArray> ToColumnArray(
+ const ArraySpan& array, LightContext* ctx,
+ const uint8_t* list_values_buffer = nullptr) {
+ KeyColumnMetadata metadata;
+ const uint8_t* validity_buffer = nullptr;
+ const uint8_t* fixed_length_buffer = nullptr;
+ const uint8_t* var_length_buffer = nullptr;
+
+ if (array.GetBuffer(0) != nullptr) {
+ validity_buffer = array.GetBuffer(0)->data();
+ }
+ if (array.GetBuffer(1) != nullptr) {
+ fixed_length_buffer = array.GetBuffer(1)->data();
+ }
+
+ auto type = array.type;
+ auto type_id = type->id();
+ if (type_id == Type::NA) {
+ metadata = KeyColumnMetadata(true, 0, true);
+ } else if (type_id == Type::BOOL) {
+ metadata = KeyColumnMetadata(true, 0);
+ } else if (is_fixed_width(type_id)) {
+ metadata = KeyColumnMetadata(true, type->bit_width() / 8);
+ } else if (is_binary_like(type_id)) {
+ metadata = KeyColumnMetadata(false, sizeof(uint32_t));
+ var_length_buffer = array.GetBuffer(2)->data();
+ } else if (is_large_binary_like(type_id)) {
+ metadata = KeyColumnMetadata(false, sizeof(uint64_t));
+ var_length_buffer = array.GetBuffer(2)->data();
+ } else if (type_id == Type::MAP) {
+ metadata = KeyColumnMetadata(false, sizeof(uint32_t));
+ var_length_buffer = list_values_buffer;
+ } else if (type_id == Type::LIST) {
+ metadata = KeyColumnMetadata(false, sizeof(uint32_t));
+ var_length_buffer = list_values_buffer;
+ } else if (type_id == Type::LARGE_LIST) {
+ metadata = KeyColumnMetadata(false, sizeof(uint64_t));
+ var_length_buffer = list_values_buffer;
+ } else if (type_id == Type::FIXED_SIZE_LIST) {
+ auto list_type = checked_cast<const FixedSizeListType*>(type);
+ metadata = KeyColumnMetadata(true, list_type->list_size());
+ fixed_length_buffer = list_values_buffer;
+ } else {
+ return Status::TypeError("Unsupported column data type ", type->name(),
+ " used with hash32/hash64 compute kernel");
+ }
+
+ return KeyColumnArray(metadata, array.length, validity_buffer,
fixed_length_buffer,
+ var_length_buffer);
+ }
+
+ static Result<std::shared_ptr<ArrayData>> HashChild(const ArraySpan& array,
+ const ArraySpan& child,
+ LightContext* hash_ctx,
+ MemoryPool* memory_pool)
{
+ auto arrow_type = TypeTraits<ArrowType>::type_singleton();
+ auto buffer_size = child.length * sizeof(c_type);
+ ARROW_ASSIGN_OR_RAISE(auto buffer, AllocateBuffer(buffer_size,
memory_pool));
Review Comment:
This is actually allocating memory within a kernel that claims to be
`MemAllocation::PREALLOCATE`. I'm not sure if this is problematic given that,
IIRC, we may do tricky things for `MemAllocation::PREALLOCATE` kernels
evaluation. @pitrou would you help to confirm that?
##########
cpp/src/arrow/util/hashing_benchmark.cc:
##########
@@ -25,11 +25,21 @@
#include "benchmark/benchmark.h"
#include "arrow/testing/gtest_util.h"
+#include "arrow/testing/random.h"
#include "arrow/util/hashing.h"
+#include "arrow/array/builder_primitive.h"
Review Comment:
Why is this separated?
##########
cpp/src/arrow/compute/CMakeLists.txt:
##########
@@ -138,6 +138,19 @@ add_arrow_compute_test(row_test
add_arrow_benchmark(function_benchmark PREFIX "arrow-compute")
+if(ARROW_TEST_LINKAGE STREQUAL "static")
+ set(ARROW_COMPUTE_BENCHMARK_LINK_LIBS arrow_compute_static)
+else()
+ set(ARROW_COMPUTE_BENCHMARK_LINK_LIBS arrow_compute_shared)
+endif()
+if(ARROW_COMPUTE)
Review Comment:
I think these might be unnecessary if you rebase to the latest main branch?
##########
cpp/src/arrow/compute/kernels/scalar_hash.cc:
##########
@@ -0,0 +1,240 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <algorithm>
+
+#include "arrow/array/array_base.h"
+#include "arrow/array/builder_primitive.h"
+#include "arrow/compute/kernels/common_internal.h"
+#include "arrow/compute/key_hash_internal.h"
+#include "arrow/compute/light_array_internal.h"
+#include "arrow/compute/util.h"
+#include "arrow/result.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+
+// Define symbols visible within `arrow::compute::internal` in this file;
+// these symbols are not visible outside of this file.
+namespace {
+
+// ------------------------------
+// Kernel implementations
+// It is expected that HashArrowType is either UInt32Type or UInt64Type
(default)
+
+template <typename ArrowType, typename Hasher>
+struct FastHashScalar {
+ using c_type = typename ArrowType::c_type;
+
+ static Result<KeyColumnArray> ToColumnArray(
Review Comment:
Since this function is not template argument depending, can we move it
outside the class to reduce the code generation?
##########
cpp/src/arrow/compute/api_scalar.h:
##########
@@ -1786,5 +1786,42 @@ ARROW_EXPORT Result<Datum> NanosecondsBetween(const
Datum& left, const Datum& ri
/// \note API not yet finalized
ARROW_EXPORT Result<Datum> MapLookup(const Datum& map, MapLookupOptions
options,
ExecContext* ctx = NULLPTR);
+
+/// \brief Construct a hash value for each row of the input.
+///
+/// The result is an Array of length equal to the length of the input;
however, the output
+/// shall be a UInt32Array, with each element being a hash constructed from
each row of
+/// the input. If the input Array is a NestedArray, this means that each
"attribute" or
+/// "field" of the input NestedArray corresponding to the same "row" will
collectively
+/// produce a single uint32_t hash. At the moment, this function does not take
options,
+/// though these may be added in the future.
+///
+/// \param[in] input_array input data to hash
+/// \param[in] ctx function execution context, optional
+/// \return elementwise hash values
+///
+/// \since 21.0.0
+/// \note API not yet finalized
+ARROW_EXPORT
+Result<Datum> Hash32(const Datum& input_array, ExecContext* ctx = NULLPTR);
+
+/// \brief Construct a hash value for each row of the input.
+///
+/// The result is an Array of length equal to the length of the input;
however, the output
+/// shall be a UInt64Array, with each element being a hash constructed from
each row of
+/// the input. If the input Array is a NestedArray, this means that each
"attribute" or
+/// "field" of the input NestedArray corresponding to the same "row" will
collectively
+/// produce a single uint64_t hash. At the moment, this function does not take
options,
+/// though these may be added in the future.
+///
+/// \param[in] input_array input data to hash
+/// \param[in] ctx function execution context, optional
+/// \return elementwise hash values
+///
+/// \since 21.0.0
Review Comment:
Hopefully it can land in 22.0.0.
##########
cpp/src/arrow/compute/api_scalar.h:
##########
@@ -1786,5 +1786,42 @@ ARROW_EXPORT Result<Datum> NanosecondsBetween(const
Datum& left, const Datum& ri
/// \note API not yet finalized
ARROW_EXPORT Result<Datum> MapLookup(const Datum& map, MapLookupOptions
options,
ExecContext* ctx = NULLPTR);
+
+/// \brief Construct a hash value for each row of the input.
+///
+/// The result is an Array of length equal to the length of the input;
however, the output
+/// shall be a UInt32Array, with each element being a hash constructed from
each row of
+/// the input. If the input Array is a NestedArray, this means that each
"attribute" or
+/// "field" of the input NestedArray corresponding to the same "row" will
collectively
+/// produce a single uint32_t hash. At the moment, this function does not take
options,
+/// though these may be added in the future.
+///
+/// \param[in] input_array input data to hash
+/// \param[in] ctx function execution context, optional
+/// \return elementwise hash values
+///
+/// \since 21.0.0
Review Comment:
```suggestion
/// \since 22.0.0
```
##########
cpp/src/arrow/compute/kernels/scalar_hash.cc:
##########
@@ -0,0 +1,240 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <algorithm>
+
+#include "arrow/array/array_base.h"
+#include "arrow/array/builder_primitive.h"
+#include "arrow/compute/kernels/common_internal.h"
+#include "arrow/compute/key_hash_internal.h"
+#include "arrow/compute/light_array_internal.h"
+#include "arrow/compute/util.h"
+#include "arrow/result.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+
+// Define symbols visible within `arrow::compute::internal` in this file;
+// these symbols are not visible outside of this file.
+namespace {
+
+// ------------------------------
+// Kernel implementations
+// It is expected that HashArrowType is either UInt32Type or UInt64Type
(default)
+
+template <typename ArrowType, typename Hasher>
+struct FastHashScalar {
+ using c_type = typename ArrowType::c_type;
+
+ static Result<KeyColumnArray> ToColumnArray(
+ const ArraySpan& array, LightContext* ctx,
+ const uint8_t* list_values_buffer = nullptr) {
Review Comment:
The `ctx` isn't used within the function.
##########
docs/source/cpp/compute.rst:
##########
@@ -1271,6 +1271,26 @@ Containment tests
* \(8) Output is true iff :member:`MatchSubstringOptions::pattern`
matches the corresponding input element at any position.
+
+Hash Functions
+~~~~~~~~~~~~~~
+
+Not to be confused with the "group by" functions, Hash functions produce an
array of hash
+values corresponding to the length of the input. Currently, these functions
take a single
+array as input.
+
++---------------+-------+-------------+-------------+---------------+-------+
+| Function name | Arity | Input types | Output type | Options class | Notes |
++===============+=======+=============+=============+===============+=======+
+| hash32 | Unary | Any | UInt32 | | \(1) |
++---------------+-------+-------------+-------------+---------------+-------+
+| hash64 | Unary | Any | UInt64 | | \(1) |
++---------------+-------+-------------+-------------+---------------+-------+
+
+* \(1) The implementation doesn't guarantee hash stability across different
versions of
+ the library. Union-, view- and run end encoded types are not supported
yet.
Review Comment:
We don't really need the dash I guess?
##########
cpp/src/arrow/compute/key_hash_benchmark.cc:
##########
@@ -0,0 +1,125 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include <algorithm>
+#include <cstdint>
+#include <limits>
+#include <random>
+#include <string>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+
+#include "arrow/testing/gtest_util.h"
+#include "arrow/testing/random.h"
+#include "arrow/util/hashing.h"
+
+#include "arrow/array/builder_primitive.h"
+#include "arrow/compute/key_hash_internal.h"
+#include "arrow/compute/util_internal.h"
+
+namespace arrow {
+namespace internal {
+
+namespace {
+// copied from scalar_string_benchmark
+constexpr auto kSeed = 0x94378165;
+
+static random::RandomArrayGenerator hashing_rng(kSeed);
+} // namespace
+
+static void KeyHashIntegers32(benchmark::State& state) { // NOLINT non-const
reference
+ auto test_vals = hashing_rng.Int32(10000, 0,
std::numeric_limits<int32_t>::max());
+
+ // initialize the stack allocator
+ util::TempVectorStack stack_memallocator;
+ ASSERT_OK(
+ stack_memallocator.Init(compute::default_exec_context()->memory_pool(),
+ 3 * sizeof(int32_t) *
util::MiniBatch::kMiniBatchLength));
+
+ // prepare the execution context for Hashing32
+ compute::LightContext hash_ctx;
+ hash_ctx.hardware_flags =
compute::default_exec_context()->cpu_info()->hardware_flags();
+ hash_ctx.stack = &stack_memallocator;
+
+ // allocate memory for results
+ ASSERT_OK_AND_ASSIGN(std::unique_ptr<Buffer> hash_buffer,
+ AllocateBuffer(test_vals->length() * sizeof(int32_t)));
+
+ // run the benchmark
+ while (state.KeepRunning()) {
+ // Prepare input data structure for propagation to hash function
+ ASSERT_OK_AND_ASSIGN(
+ compute::KeyColumnArray input_keycol,
+ compute::ColumnArrayFromArrayData(test_vals->data(), 0,
test_vals->length()));
+
+ compute::Hashing32::HashMultiColumn(
+ {input_keycol}, &hash_ctx,
+ reinterpret_cast<uint32_t*>(hash_buffer->mutable_data()));
+
+ // benchmark::DoNotOptimize(hash_buffer);
+ }
+
+ state.SetBytesProcessed(state.iterations() * test_vals->length() *
sizeof(int32_t));
+ state.SetItemsProcessed(state.iterations() * test_vals->length());
+}
+
+static void KeyHashIntegers64(benchmark::State& state) { // NOLINT non-const
reference
+ auto test_vals = hashing_rng.Int64(10000, 0,
std::numeric_limits<int64_t>::max());
+
+ // initialize the stack allocator
+ util::TempVectorStack stack_memallocator;
+ ASSERT_OK(
+ stack_memallocator.Init(compute::default_exec_context()->memory_pool(),
+ 3 * sizeof(int32_t) *
util::MiniBatch::kMiniBatchLength));
+
+ // prepare the execution context for Hashing32
+ compute::LightContext hash_ctx;
+ hash_ctx.hardware_flags =
compute::default_exec_context()->cpu_info()->hardware_flags();
+ hash_ctx.stack = &stack_memallocator;
+
+ // allocate memory for results
+ ASSERT_OK_AND_ASSIGN(std::unique_ptr<Buffer> hash_buffer,
+ AllocateBuffer(test_vals->length() * sizeof(int64_t)));
+
+ // run the benchmark
+ while (state.KeepRunning()) {
+ // Prepare input data structure for propagation to hash function
+ ASSERT_OK_AND_ASSIGN(
+ compute::KeyColumnArray input_keycol,
+ compute::ColumnArrayFromArrayData(test_vals->data(), 0,
test_vals->length()));
+
+ compute::Hashing64::HashMultiColumn(
+ {input_keycol}, &hash_ctx,
+ reinterpret_cast<uint64_t*>(hash_buffer->mutable_data()));
+
+ // benchmark::DoNotOptimize(hash_buffer);
Review Comment:
```suggestion
```
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