ARROW-13390: [C++] Implement coalesce for remaining types

c_glib/test/test-dense-union-scalar.rb

@@ -49,7 +49,7 @@ def test_equal
  end
 
  def test_to_s
- assert_equal("...", @scalar.to_s)
+ assert_equal("union{number: int8 = -29}", @scalar.to_s)
  end
 
  def test_value

c_glib/test/test-sparse-union-scalar.rb

@@ -49,7 +49,7 @@ def test_equal
  end
 
  def test_to_s
- assert_equal("...", @scalar.to_s)
+ assert_equal("union{number: int8 = -29}", @scalar.to_s)
  end
 
  def test_value

cpp/src/arrow/compute/kernels/CMakeLists.txt

@@ -71,3 +71,8 @@ add_arrow_compute_test(aggregate_test
  hash_aggregate_test.cc
  test_util.cc)
 add_arrow_benchmark(aggregate_benchmark PREFIX "arrow-compute")
+
+# ----------------------------------------------------------------------
+# Utilities
+
+add_arrow_compute_test(kernel_utility_test SOURCES codegen_internal_test.cc)

cpp/src/arrow/compute/kernels/codegen_internal.cc

@@ -95,8 +95,14 @@ void ReplaceNullWithOtherType(std::vector<ValueDescr>* descrs) {
 
 void ReplaceTypes(const std::shared_ptr<DataType>& type,
  std::vector<ValueDescr>* descrs) {
- for (auto& descr : *descrs) {
- descr.type = type;
+ ReplaceTypes(type, descrs->data(), descrs->size());
+}
+
+void ReplaceTypes(const std::shared_ptr<DataType>& type, ValueDescr* begin,
+ size_t count) {
+ auto* end = begin + count;
+ for (auto* it = begin; it != end; it++) {
+ it->type = type;
  }
 }
 
@@ -158,26 +164,47 @@ std::shared_ptr<DataType> CommonNumeric(const ValueDescr* begin, size_t count) {
  return int8();
 }
 
-std::shared_ptr<DataType> CommonTimestamp(const std::vector<ValueDescr>& descrs) {
+std::shared_ptr<DataType> CommonTemporal(const std::vector<ValueDescr>& descrs) {
  TimeUnit::type finest_unit = TimeUnit::SECOND;
+ const std::string* timezone = nullptr;
+ bool saw_date32 = false;
+ bool saw_date64 = false;
 
  for (const auto& descr : descrs) {
  auto id = descr.type->id();
  // a common timestamp is only possible if all types are timestamp like
  switch (id) {
  case Type::DATE32:
+ // Date32's unit is days, but the coarsest we have is seconds
+ saw_date32 = true;
+ continue;
  case Type::DATE64:
+ finest_unit = std::max(finest_unit, TimeUnit::MILLI);
+ saw_date64 = true;
  continue;
- case Type::TIMESTAMP:
- finest_unit =
- std::max(finest_unit, checked_cast<const TimestampType&>(*descr.type).unit());
+ case Type::TIMESTAMP: {
+ const auto& ty = checked_cast<const TimestampType&>(*descr.type);
+ // Don't cast to common timezone by default (may not make
+ // sense for all kernels)
+ if (timezone && *timezone != ty.timezone()) return nullptr;
+ timezone = &ty.timezone();
+ finest_unit = std::max(finest_unit, ty.unit());
  continue;
+ }
  default:
  return nullptr;
  }
  }
 
- return timestamp(finest_unit);
+ if (timezone) {
+ // At least one timestamp seen
+ return timestamp(finest_unit, *timezone);
+ } else if (saw_date64) {
+ return date64();
+ } else if (saw_date32) {
+ return date32();
+ }
+ return nullptr;
 }
 
 std::shared_ptr<DataType> CommonBinary(const std::vector<ValueDescr>& descrs) {
@@ -290,6 +317,67 @@ Status CastBinaryDecimalArgs(DecimalPromotion promotion,
  return Status::OK();
 }
 
+Status CastDecimalArgs(ValueDescr* begin, size_t count) {
+ Type::type casted_type_id = Type::DECIMAL128;
+ auto* end = begin + count;
+
+ int32_t max_scale = 0;
+ bool any_floating = false;
+ for (auto* it = begin; it != end; ++it) {
+ const auto& ty = *it->type;
+ if (is_floating(ty.id())) {
+ // Decimal + float = float
+ any_floating = true;
+ } else if (is_integer(ty.id())) {
+ // Nothing to do here
+ } else if (is_decimal(ty.id())) {
+ max_scale = std::max(max_scale, checked_cast<const DecimalType&>(ty).scale());
+ if (ty.id() == Type::DECIMAL256) {
+ casted_type_id = Type::DECIMAL256;
+ }
+ } else {
+ // Non-numeric, can't cast
+ return Status::OK();
+ }
+ }
+ if (any_floating) {
+ ReplaceTypes(float64(), begin, count);
+ return Status::OK();
+ }
+
+ // All integer and decimal, rescale
+ int32_t common_precision = 0;
+ for (auto* it = begin; it != end; ++it) {
+ const auto& ty = *it->type;
+ if (is_integer(ty.id())) {
+ ARROW_ASSIGN_OR_RAISE(auto precision, MaxDecimalDigitsForInteger(ty.id()));
+ precision += max_scale;
+ common_precision = std::max(common_precision, precision);
+ } else if (is_decimal(ty.id())) {
+ const auto& decimal_ty = checked_cast<const DecimalType&>(ty);
+ auto precision = decimal_ty.precision();
+ const auto scale = decimal_ty.scale();
+ precision += max_scale - scale;
+ common_precision = std::max(common_precision, precision);
+ }
+ }
+
+ if (common_precision > BasicDecimal256::kMaxPrecision) {
+ return Status::Invalid("Result precision (", common_precision,
+ ") exceeds max precision of Decimal256 (",
+ BasicDecimal256::kMaxPrecision, ")");
+ } else if (common_precision > BasicDecimal128::kMaxPrecision) {
+ casted_type_id = Type::DECIMAL256;
+ }
+
+ for (auto* it = begin; it != end; ++it) {
+ ARROW_ASSIGN_OR_RAISE(it->type,
+ DecimalType::Make(casted_type_id, common_precision, max_scale));
+ }
+
+ return Status::OK();
+}
+
 bool HasDecimal(const std::vector<ValueDescr>& descrs) {
  for (const auto& descr : descrs) {
  if (is_decimal(descr.type->id())) {

cpp/src/arrow/compute/kernels/codegen_internal.h

@@ -1279,14 +1279,17 @@ void ReplaceNullWithOtherType(std::vector<ValueDescr>* descrs);
 ARROW_EXPORT
 void ReplaceTypes(const std::shared_ptr<DataType>&, std::vector<ValueDescr>* descrs);
 
+ARROW_EXPORT
+void ReplaceTypes(const std::shared_ptr<DataType>&, ValueDescr* descrs, size_t count);
+
 ARROW_EXPORT
 std::shared_ptr<DataType> CommonNumeric(const std::vector<ValueDescr>& descrs);
 
 ARROW_EXPORT
 std::shared_ptr<DataType> CommonNumeric(const ValueDescr* begin, size_t count);
 
 ARROW_EXPORT
-std::shared_ptr<DataType> CommonTimestamp(const std::vector<ValueDescr>& descrs);
+std::shared_ptr<DataType> CommonTemporal(const std::vector<ValueDescr>& descrs);
 
 ARROW_EXPORT
 std::shared_ptr<DataType> CommonBinary(const std::vector<ValueDescr>& descrs);
@@ -1298,9 +1301,17 @@ enum class DecimalPromotion : uint8_t {
  kDivide,
 };
 
+/// Given two arguments, at least one of which is decimal, promote all
+/// to not necessarily identical types, but types which are compatible
+/// for the given operator (add/multiply/divide).
 ARROW_EXPORT
 Status CastBinaryDecimalArgs(DecimalPromotion promotion, std::vector<ValueDescr>* descrs);
 
+/// Given one or more arguments, at least one of which is decimal,
+/// promote all to an identical type.
+ARROW_EXPORT
+Status CastDecimalArgs(ValueDescr* begin, size_t count);
+
 ARROW_EXPORT
 bool HasDecimal(const std::vector<ValueDescr>& descrs);
 

cpp/src/arrow/compute/kernels/codegen_internal_test.cc

@@ -0,0 +1,155 @@
+// 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 <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include "arrow/compute/kernels/codegen_internal.h"
+#include "arrow/testing/gtest_util.h"
+#include "arrow/type.h"
+#include "arrow/type_fwd.h"
+
+namespace arrow {
+namespace compute {
+namespace internal {
+
+TEST(TestDispatchBest, CastBinaryDecimalArgs) {
+ std::vector<ValueDescr> args;
+ std::vector<DecimalPromotion> modes = {
+ DecimalPromotion::kAdd, DecimalPromotion::kMultiply, DecimalPromotion::kDivide};
+
+ // Any float -> all float
+ for (auto mode : modes) {
+ args = {decimal128(3, 2), float64()};
+ ASSERT_OK(CastBinaryDecimalArgs(mode, &args));
+ AssertTypeEqual(args[0].type, float64());
+ AssertTypeEqual(args[1].type, float64());
+ }
+
+ // Integer -> decimal with common scale
+ args = {decimal128(1, 0), int64()};
+ ASSERT_OK(CastBinaryDecimalArgs(DecimalPromotion::kAdd, &args));
+ AssertTypeEqual(args[0].type, decimal128(1, 0));
+ AssertTypeEqual(args[1].type, decimal128(19, 0));
+
+ // Add: rescale so all have common scale
+ args = {decimal128(3, 2), decimal128(3, -2)};
+ EXPECT_RAISES_WITH_MESSAGE_THAT(
+ NotImplemented, ::testing::HasSubstr("Decimals with negative scales not supported"),
+ CastBinaryDecimalArgs(DecimalPromotion::kAdd, &args));
+}
+
+TEST(TestDispatchBest, CastDecimalArgs) {
+ std::vector<ValueDescr> args;
+
+ // Any float -> all float
+ args = {decimal128(3, 2), float64()};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, float64());
+ AssertTypeEqual(args[1].type, float64());
+
+ args = {float32(), float64(), decimal128(3, 2)};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, float64());
+ AssertTypeEqual(args[1].type, float64());
+ AssertTypeEqual(args[2].type, float64());
+
+ // Promote to common decimal width
+ args = {decimal128(3, 2), decimal256(3, 2)};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal256(3, 2));
+ AssertTypeEqual(args[1].type, decimal256(3, 2));
+
+ // Rescale so all have common scale/precision
+ args = {decimal128(3, 2), decimal128(3, 0)};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal128(5, 2));
+ AssertTypeEqual(args[1].type, decimal128(5, 2));
+
+ args = {decimal128(3, 2), decimal128(3, -2)};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal128(7, 2));
+ AssertTypeEqual(args[1].type, decimal128(7, 2));
+
+ args = {decimal128(3, 0), decimal128(3, 1), decimal128(3, 2)};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal128(5, 2));
+ AssertTypeEqual(args[1].type, decimal128(5, 2));
+ AssertTypeEqual(args[2].type, decimal128(5, 2));
+
+ // Integer -> decimal with appropriate precision
+ args = {decimal128(3, 0), int64()};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal128(19, 0));
+ AssertTypeEqual(args[1].type, decimal128(19, 0));
+
+ args = {decimal128(3, 1), int64()};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal128(20, 1));
+ AssertTypeEqual(args[1].type, decimal128(20, 1));
+
+ args = {decimal128(3, -1), int64()};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal128(19, 0));
+ AssertTypeEqual(args[1].type, decimal128(19, 0));
+
+ // Overflow decimal128 max precision -> promote to decimal256
+ args = {decimal128(38, 0), decimal128(37, 2)};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal256(40, 2));
+ AssertTypeEqual(args[1].type, decimal256(40, 2));
+
+ // Overflow decimal256 max precision
+ args = {decimal256(76, 0), decimal256(75, 1)};
+ EXPECT_RAISES_WITH_MESSAGE_THAT(
+ Invalid,
+ ::testing::HasSubstr(
+ "Result precision (77) exceeds max precision of Decimal256 (76)"),
+ CastDecimalArgs(args.data(), args.size()));
+
+ // Incompatible, no cast
+ args = {decimal256(3, 2), float64(), utf8()};
+ ASSERT_OK(CastDecimalArgs(args.data(), args.size()));
+ AssertTypeEqual(args[0].type, decimal256(3, 2));
+ AssertTypeEqual(args[1].type, float64());
+ AssertTypeEqual(args[2].type, utf8());
+}
+
+TEST(TestDispatchBest, CommonTemporal) {
+ AssertTypeEqual(timestamp(TimeUnit::NANO), CommonTemporal({timestamp(TimeUnit::SECOND),
+ timestamp(TimeUnit::NANO)}));
+ AssertTypeEqual(timestamp(TimeUnit::NANO, "UTC"),
+ CommonTemporal({timestamp(TimeUnit::SECOND, "UTC"),
+ timestamp(TimeUnit::NANO, "UTC")}));
+ AssertTypeEqual(timestamp(TimeUnit::NANO),
+ CommonTemporal({date32(), timestamp(TimeUnit::NANO)}));
+ AssertTypeEqual(timestamp(TimeUnit::MILLI),
+ CommonTemporal({date64(), timestamp(TimeUnit::SECOND)}));
+ AssertTypeEqual(date32(), CommonTemporal({date32(), date32()}));
+ AssertTypeEqual(date64(), CommonTemporal({date64(), date64()}));
+ AssertTypeEqual(date64(), CommonTemporal({date32(), date64()}));
+ ASSERT_EQ(nullptr, CommonTemporal({}));
+ ASSERT_EQ(nullptr, CommonTemporal({float64(), int32()}));
+ ASSERT_EQ(nullptr, CommonTemporal({timestamp(TimeUnit::SECOND),
+ timestamp(TimeUnit::SECOND, "UTC")}));
+ ASSERT_EQ(nullptr, CommonTemporal({timestamp(TimeUnit::SECOND, "America/Phoenix"),
+ timestamp(TimeUnit::SECOND, "UTC")}));
+}
+
+} // namespace internal
+} // namespace compute
+} // namespace arrow