feat(parquet): apply column default values when reading missing fields (2/4)

huan233usc · huan233usc · commit 8db3067e4429 · 2026-06-29T19:55:17.000-07:00
When a column is present in the read schema but missing from a Parquet data file (written before the column existed), fill it with the column's v3 initial-default instead of null. Adds a shared Arrow materializer (arrow/literal_util) that turns a Literal into an Arrow scalar/array, and a kDefault projection branch in the Parquet schema/data projection paths. The materializer wraps the storage array in the extension type for extension types such as `arrow.uuid` (compute::Cast has no storage->extension kernel). Part 2 of the v3 column-default-values work (POC #731), built on the schema support merged in #746.
diff --git a/src/iceberg/CMakeLists.txt b/src/iceberg/CMakeLists.txt
@@ -261,6 +261,7 @@ if(ICEBERG_BUILD_BUNDLE)
       arrow/arrow_io.cc
       arrow/s3/arrow_s3_file_io.cc
       arrow/arrow_register.cc
+      arrow/literal_util.cc
       arrow/metadata_column_util.cc
       avro/avro_data_util.cc
       avro/avro_direct_decoder.cc
diff --git a/src/iceberg/arrow/literal_util.cc b/src/iceberg/arrow/literal_util.cc
@@ -0,0 +1,208 @@
+/*
+ * 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 <cstring>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <arrow/array.h>
+#include <arrow/array/builder_base.h>
+#include <arrow/array/util.h>
+#include <arrow/buffer.h>
+#include <arrow/compute/api.h>
+#include <arrow/extension_type.h>
+#include <arrow/scalar.h>
+#include <arrow/type.h>
+
+#include "iceberg/arrow/arrow_status_internal.h"
+#include "iceberg/arrow/literal_util_internal.h"
+#include "iceberg/type.h"
+#include "iceberg/util/checked_cast.h"
+#include "iceberg/util/formatter.h"  // IWYU pragma: keep
+#include "iceberg/util/macros.h"
+
+namespace iceberg::arrow {
+
+namespace {
+
+Result<std::shared_ptr<::arrow::DataType>> ToArrowType(const PrimitiveType& type) {
+  switch (type.type_id()) {
+    case TypeId::kBoolean:
+      return ::arrow::boolean();
+    case TypeId::kInt:
+      return ::arrow::int32();
+    case TypeId::kLong:
+      return ::arrow::int64();
+    case TypeId::kFloat:
+      return ::arrow::float32();
+    case TypeId::kDouble:
+      return ::arrow::float64();
+    case TypeId::kDecimal: {
+      const auto& decimal_type = internal::checked_cast<const DecimalType&>(type);
+      return ::arrow::decimal128(decimal_type.precision(), decimal_type.scale());
+    }
+    case TypeId::kDate:
+      return ::arrow::date32();
+    case TypeId::kTime:
+      return ::arrow::time64(::arrow::TimeUnit::MICRO);
+    case TypeId::kTimestamp:
+      return ::arrow::timestamp(::arrow::TimeUnit::MICRO);
+    case TypeId::kTimestampTz:
+      return ::arrow::timestamp(::arrow::TimeUnit::MICRO, "UTC");
+    case TypeId::kTimestampNs:
+      return ::arrow::timestamp(::arrow::TimeUnit::NANO);
+    case TypeId::kTimestampTzNs:
+      return ::arrow::timestamp(::arrow::TimeUnit::NANO, "UTC");
+    case TypeId::kString:
+      return ::arrow::utf8();
+    case TypeId::kBinary:
+      return ::arrow::binary();
+    case TypeId::kFixed: {
+      const auto& fixed_type = internal::checked_cast<const FixedType&>(type);
+      return ::arrow::fixed_size_binary(static_cast<int32_t>(fixed_type.length()));
+    }
+    case TypeId::kUuid:
+      return ::arrow::fixed_size_binary(16);
+    default:
+      return NotSupported("Cannot convert {} to an Arrow type", type);
+  }
+}
+
+Result<std::shared_ptr<::arrow::Buffer>> ToArrowBuffer(
+    const std::vector<uint8_t>& bytes) {
+  ICEBERG_ARROW_ASSIGN_OR_RETURN(std::unique_ptr<::arrow::Buffer> buffer,
+                                 ::arrow::AllocateBuffer(bytes.size()));
+  std::memcpy(buffer->mutable_data(), bytes.data(), bytes.size());
+  return std::shared_ptr<::arrow::Buffer>(std::move(buffer));
+}
+
+}  // namespace
+
+Result<std::shared_ptr<::arrow::Scalar>> ToArrowScalar(const Literal& literal) {
+  if (literal.type() == nullptr) {
+    return InvalidArgument("Cannot convert a literal without type to an Arrow scalar");
+  }
+
+  if (literal.IsAboveMax() || literal.IsBelowMin()) {
+    return NotSupported("Cannot convert {} to an Arrow scalar", literal);
+  }
+
+  ICEBERG_ASSIGN_OR_RAISE(std::shared_ptr<::arrow::DataType> arrow_type,
+                          ToArrowType(*literal.type()));
+  if (literal.IsNull()) {
+    return ::arrow::MakeNullScalar(std::move(arrow_type));
+  }
+
+  const Literal::Value& value = literal.value();
+  switch (literal.type()->type_id()) {
+    case TypeId::kBoolean:
+      return std::make_shared<::arrow::BooleanScalar>(std::get<bool>(value));
+    case TypeId::kInt:
+      return std::make_shared<::arrow::Int32Scalar>(std::get<int32_t>(value));
+    case TypeId::kLong:
+      return std::make_shared<::arrow::Int64Scalar>(std::get<int64_t>(value));
+    case TypeId::kFloat:
+      return std::make_shared<::arrow::FloatScalar>(std::get<float>(value));
+    case TypeId::kDouble:
+      return std::make_shared<::arrow::DoubleScalar>(std::get<double>(value));
+    case TypeId::kDecimal: {
+      const auto& decimal = std::get<Decimal>(value);
+      ::arrow::Decimal128 arrow_decimal(
+          static_cast<int64_t>(decimal.value() >> 64),
+          static_cast<uint64_t>(decimal.value() & ~uint64_t{0}));
+      return std::make_shared<::arrow::Decimal128Scalar>(arrow_decimal,
+                                                         std::move(arrow_type));
+    }
+    case TypeId::kDate:
+      return std::make_shared<::arrow::Date32Scalar>(std::get<int32_t>(value));
+    case TypeId::kTime:
+      return std::make_shared<::arrow::Time64Scalar>(std::get<int64_t>(value),
+                                                     std::move(arrow_type));
+    case TypeId::kTimestamp:
+    case TypeId::kTimestampTz:
+    case TypeId::kTimestampNs:
+    case TypeId::kTimestampTzNs:
+      return std::make_shared<::arrow::TimestampScalar>(std::get<int64_t>(value),
+                                                        std::move(arrow_type));
+    case TypeId::kString:
+      return std::make_shared<::arrow::StringScalar>(std::get<std::string>(value));
+    case TypeId::kBinary: {
+      ICEBERG_ASSIGN_OR_RAISE(std::shared_ptr<::arrow::Buffer> buffer,
+                              ToArrowBuffer(std::get<std::vector<uint8_t>>(value)));
+      return std::make_shared<::arrow::BinaryScalar>(std::move(buffer));
+    }
+    case TypeId::kFixed: {
+      ICEBERG_ASSIGN_OR_RAISE(std::shared_ptr<::arrow::Buffer> buffer,
+                              ToArrowBuffer(std::get<std::vector<uint8_t>>(value)));
+      return std::make_shared<::arrow::FixedSizeBinaryScalar>(std::move(buffer),
+                                                              std::move(arrow_type));
+    }
+    case TypeId::kUuid: {
+      const Uuid& uuid = std::get<Uuid>(value);
+      ICEBERG_ASSIGN_OR_RAISE(
+          std::shared_ptr<::arrow::Buffer> buffer,
+          ToArrowBuffer(std::vector<uint8_t>(uuid.bytes().begin(), uuid.bytes().end())));
+      return std::make_shared<::arrow::FixedSizeBinaryScalar>(std::move(buffer),
+                                                              std::move(arrow_type));
+    }
+    default:
+      return NotSupported("Cannot convert {} literal to an Arrow scalar",
+                          *literal.type());
+  }
+}
+
+Result<std::shared_ptr<::arrow::Array>> MakeDefaultArray(
+    const Literal& literal, const std::shared_ptr<::arrow::DataType>& type,
+    int64_t num_rows, ::arrow::MemoryPool* pool) {
+  // An extension type (e.g. `arrow.uuid` for an Iceberg UUID) is backed by a storage
+  // type, and compute::Cast has no kernel that casts a storage array into an extension
+  // type. Materialize the array as the storage type and wrap it in the extension type.
+  if (type->id() == ::arrow::Type::EXTENSION) {
+    const auto& extension_type =
+        internal::checked_cast<const ::arrow::ExtensionType&>(*type);
+    ICEBERG_ASSIGN_OR_RAISE(
+        std::shared_ptr<::arrow::Array> storage,
+        MakeDefaultArray(literal, extension_type.storage_type(), num_rows, pool));
+    return ::arrow::ExtensionType::WrapArray(type, storage);
+  }
+
+  ICEBERG_ASSIGN_OR_RAISE(std::shared_ptr<::arrow::Scalar> scalar,
+                          ToArrowScalar(literal));
+  ICEBERG_ARROW_ASSIGN_OR_RETURN(std::shared_ptr<::arrow::Array> array,
+                                 ::arrow::MakeArrayFromScalar(*scalar, num_rows, pool));
+  if (!array->type()->Equals(*type)) {
+    ICEBERG_ARROW_ASSIGN_OR_RETURN(::arrow::Datum cast_result,
+                                   ::arrow::compute::Cast(array, type));
+    return cast_result.make_array();
+  }
+  return array;
+}
+
+Status AppendDefaultToBuilder(const Literal& literal, ::arrow::ArrayBuilder* builder) {
+  ICEBERG_ASSIGN_OR_RAISE(std::shared_ptr<::arrow::Scalar> scalar,
+                          ToArrowScalar(literal));
+  if (!scalar->type->Equals(*builder->type())) {
+    ICEBERG_ARROW_ASSIGN_OR_RETURN(scalar, scalar->CastTo(builder->type()));
+  }
+  ICEBERG_ARROW_RETURN_NOT_OK(builder->AppendScalar(*scalar));
+  return {};
+}
+
+}  // namespace iceberg::arrow
diff --git a/src/iceberg/arrow/literal_util_internal.h b/src/iceberg/arrow/literal_util_internal.h
@@ -0,0 +1,49 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <memory>
+
+#include <arrow/type_fwd.h>
+
+#include "iceberg/expression/literal.h"
+#include "iceberg/result.h"
+
+namespace iceberg::arrow {
+
+/// \brief Convert a primitive literal to an Arrow scalar of its canonical Arrow type.
+///
+/// A null literal converts to a null scalar of the corresponding Arrow type.
+Result<std::shared_ptr<::arrow::Scalar>> ToArrowScalar(const Literal& literal);
+
+/// \brief Create an Arrow array of `num_rows` rows where every row holds the literal
+/// value, e.g. to materialize a missing column with a default value.
+///
+/// The array is cast to `type` when the literal's canonical Arrow type differs.
+Result<std::shared_ptr<::arrow::Array>> MakeDefaultArray(
+    const Literal& literal, const std::shared_ptr<::arrow::DataType>& type,
+    int64_t num_rows, ::arrow::MemoryPool* pool);
+
+/// \brief Append the literal value once to `builder`, e.g. to materialize a missing
+/// field with a default value while building rows.
+Status AppendDefaultToBuilder(const Literal& literal, ::arrow::ArrayBuilder* builder);
+
+}  // namespace iceberg::arrow
diff --git a/src/iceberg/parquet/parquet_data_util.cc b/src/iceberg/parquet/parquet_data_util.cc
@@ -24,6 +24,7 @@
 #include <arrow/type.h>
 
 #include "iceberg/arrow/arrow_status_internal.h"
+#include "iceberg/arrow/literal_util_internal.h"
 #include "iceberg/metadata_columns.h"
 #include "iceberg/parquet/parquet_data_util_internal.h"
 #include "iceberg/schema.h"
@@ -119,6 +120,11 @@ Result<std::shared_ptr<::arrow::Array>> ProjectStructArray(
       ICEBERG_ASSIGN_OR_RAISE(
           projected_array,
           MakeNullArray(output_arrow_type, struct_array->length(), pool));
+    } else if (field_projection.kind == FieldProjection::Kind::kDefault) {
+      ICEBERG_ASSIGN_OR_RAISE(
+          projected_array,
+          arrow::MakeDefaultArray(std::get<Literal>(field_projection.from),
+                                  output_arrow_type, struct_array->length(), pool));
     } else if (field_projection.kind == FieldProjection::Kind::kMetadata) {
       int32_t field_id = projected_field.field_id();
       if (field_id == MetadataColumns::kFilePathColumnId) {
diff --git a/src/iceberg/parquet/parquet_schema_util.cc b/src/iceberg/parquet/parquet_schema_util.cc
@@ -341,6 +341,10 @@ Result<FieldProjection> ProjectStruct(
           child_projection, ProjectField(field, parquet_field, iter->second.local_index));
     } else if (MetadataColumns::IsMetadataColumn(field_id)) {
       child_projection.kind = FieldProjection::Kind::kMetadata;
+    } else if (field.initial_default() != nullptr) {
+      // Rows written before the field existed assume its `initial-default` value.
+      child_projection.kind = FieldProjection::Kind::kDefault;
+      child_projection.from = *field.initial_default();
     } else if (field.optional()) {
       child_projection.kind = FieldProjection::Kind::kNull;
     } else {
diff --git a/src/iceberg/test/CMakeLists.txt b/src/iceberg/test/CMakeLists.txt
@@ -253,7 +253,8 @@ if(ICEBERG_BUILD_BUNDLE)
                    data_writer_test.cc
                    delete_filter_test.cc
                    delete_loader_test.cc
-                   file_scan_task_reader_test.cc)
+                   file_scan_task_reader_test.cc
+                   literal_util_test.cc)
 
 endif()
 
diff --git a/src/iceberg/test/literal_util_test.cc b/src/iceberg/test/literal_util_test.cc
diff --git a/src/iceberg/test/parquet_data_test.cc b/src/iceberg/test/parquet_data_test.cc
diff --git a/src/iceberg/test/parquet_test.cc b/src/iceberg/test/parquet_test.cc
