[GitHub] [parquet-cpp] pitrou commented on a change in pull request #158: PARQUET-712: Add library to read into Arrow memory

[GitBox <gi...@apache.org>]

pitrou commented on a change in pull request #158:
URL: https://github.com/apache/parquet-cpp/pull/158#discussion_r607025397



##########
File path: src/parquet/arrow/schema.cc
##########
@@ -0,0 +1,351 @@
+// 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 "parquet/arrow/schema.h"
+
+#include <string>
+#include <vector>
+
+#include "parquet/api/schema.h"
+#include "parquet/arrow/utils.h"
+
+#include "arrow/types/decimal.h"
+#include "arrow/types/string.h"
+#include "arrow/util/status.h"
+
+using arrow::Field;
+using arrow::Status;
+using arrow::TypePtr;
+
+using ArrowType = arrow::Type;
+
+using parquet::Repetition;
+using parquet::schema::Node;
+using parquet::schema::NodePtr;
+using parquet::schema::GroupNode;
+using parquet::schema::PrimitiveNode;
+
+using ParquetType = parquet::Type;
+using parquet::LogicalType;
+
+namespace parquet {
+
+namespace arrow {
+
+const auto BOOL = std::make_shared<::arrow::BooleanType>();
+const auto UINT8 = std::make_shared<::arrow::UInt8Type>();
+const auto INT8 = std::make_shared<::arrow::Int8Type>();
+const auto UINT16 = std::make_shared<::arrow::UInt16Type>();
+const auto INT16 = std::make_shared<::arrow::Int16Type>();
+const auto UINT32 = std::make_shared<::arrow::UInt32Type>();
+const auto INT32 = std::make_shared<::arrow::Int32Type>();
+const auto UINT64 = std::make_shared<::arrow::UInt64Type>();
+const auto INT64 = std::make_shared<::arrow::Int64Type>();
+const auto FLOAT = std::make_shared<::arrow::FloatType>();
+const auto DOUBLE = std::make_shared<::arrow::DoubleType>();
+const auto UTF8 = std::make_shared<::arrow::StringType>();
+const auto TIMESTAMP_MS =
+    std::make_shared<::arrow::TimestampType>(::arrow::TimestampType::Unit::MILLI);
+const auto BINARY =
+    std::make_shared<::arrow::ListType>(std::make_shared<::arrow::Field>("", UINT8));
+
+TypePtr MakeDecimalType(const PrimitiveNode* node) {
+  int precision = node->decimal_metadata().precision;
+  int scale = node->decimal_metadata().scale;
+  return std::make_shared<::arrow::DecimalType>(precision, scale);
+}
+
+static Status FromByteArray(const PrimitiveNode* node, TypePtr* out) {
+  switch (node->logical_type()) {
+    case LogicalType::UTF8:
+      *out = UTF8;
+      break;
+    case LogicalType::DECIMAL:
+      *out = MakeDecimalType(node);
+      break;
+    default:
+      // BINARY
+      *out = BINARY;
+      break;
+  }
+  return Status::OK();
+}
+
+static Status FromFLBA(const PrimitiveNode* node, TypePtr* out) {
+  switch (node->logical_type()) {
+    case LogicalType::NONE:
+      *out = BINARY;
+      break;
+    case LogicalType::DECIMAL:
+      *out = MakeDecimalType(node);
+      break;
+    default:
+      return Status::NotImplemented("unhandled type");
+      break;
+  }
+
+  return Status::OK();
+}
+
+static Status FromInt32(const PrimitiveNode* node, TypePtr* out) {
+  switch (node->logical_type()) {
+    case LogicalType::NONE:
+      *out = INT32;
+      break;
+    case LogicalType::UINT_8:
+      *out = UINT8;
+      break;
+    case LogicalType::INT_8:
+      *out = INT8;
+      break;
+    case LogicalType::UINT_16:
+      *out = UINT16;
+      break;
+    case LogicalType::INT_16:
+      *out = INT16;
+      break;
+    case LogicalType::UINT_32:
+      *out = UINT32;
+      break;
+    case LogicalType::DECIMAL:
+      *out = MakeDecimalType(node);
+      break;
+    default:
+      return Status::NotImplemented("Unhandled logical type for int32");
+      break;
+  }
+  return Status::OK();
+}
+
+static Status FromInt64(const PrimitiveNode* node, TypePtr* out) {
+  switch (node->logical_type()) {
+    case LogicalType::NONE:
+      *out = INT64;
+      break;
+    case LogicalType::UINT_64:
+      *out = UINT64;
+      break;
+    case LogicalType::DECIMAL:
+      *out = MakeDecimalType(node);
+      break;
+    case LogicalType::TIMESTAMP_MILLIS:
+      *out = TIMESTAMP_MS;
+      break;
+    default:
+      return Status::NotImplemented("Unhandled logical type for int64");
+      break;
+  }
+  return Status::OK();
+}
+
+// TODO: Logical Type Handling
+Status NodeToField(const NodePtr& node, std::shared_ptr<Field>* out) {
+  std::shared_ptr<::arrow::DataType> type;
+
+  if (node->is_repeated()) {
+    return Status::NotImplemented("No support yet for repeated node types");
+  }
+
+  if (node->is_group()) {
+    const GroupNode* group = static_cast<const GroupNode*>(node.get());
+    std::vector<std::shared_ptr<Field>> fields(group->field_count());
+    for (int i = 0; i < group->field_count(); i++) {
+      RETURN_NOT_OK(NodeToField(group->field(i), &fields[i]));
+    }
+    type = std::make_shared<::arrow::StructType>(fields);
+  } else {
+    // Primitive (leaf) node
+    const PrimitiveNode* primitive = static_cast<const PrimitiveNode*>(node.get());
+
+    switch (primitive->physical_type()) {
+      case ParquetType::BOOLEAN:
+        type = BOOL;
+        break;
+      case ParquetType::INT32:
+        RETURN_NOT_OK(FromInt32(primitive, &type));
+        break;
+      case ParquetType::INT64:
+        RETURN_NOT_OK(FromInt64(primitive, &type));
+        break;
+      case ParquetType::INT96:
+        // TODO: Do we have that type in Arrow?
+        // type = TypePtr(new Int96Type());
+        return Status::NotImplemented("int96");
+      case ParquetType::FLOAT:
+        type = FLOAT;
+        break;
+      case ParquetType::DOUBLE:
+        type = DOUBLE;
+        break;
+      case ParquetType::BYTE_ARRAY:
+        // TODO: Do we have that type in Arrow?
+        RETURN_NOT_OK(FromByteArray(primitive, &type));
+        break;
+      case ParquetType::FIXED_LEN_BYTE_ARRAY:
+        RETURN_NOT_OK(FromFLBA(primitive, &type));
+        break;
+    }
+  }
+
+  *out = std::make_shared<Field>(node->name(), type, !node->is_required());
+  return Status::OK();
+}
+
+Status FromParquetSchema(
+    const SchemaDescriptor* parquet_schema, std::shared_ptr<::arrow::Schema>* out) {
+  // TODO(wesm): Consider adding an arrow::Schema name attribute, which comes
+  // from the root Parquet node
+  const GroupNode* schema_node = parquet_schema->group_node();
+
+  std::vector<std::shared_ptr<Field>> fields(schema_node->field_count());
+  for (int i = 0; i < schema_node->field_count(); i++) {
+    RETURN_NOT_OK(NodeToField(schema_node->field(i), &fields[i]));
+  }
+
+  *out = std::make_shared<::arrow::Schema>(fields);
+  return Status::OK();
+}
+
+Status StructToNode(const std::shared_ptr<::arrow::StructType>& type,
+    const std::string& name, bool nullable, const WriterProperties& properties,
+    NodePtr* out) {
+  Repetition::type repetition = Repetition::REQUIRED;
+  if (nullable) { repetition = Repetition::OPTIONAL; }
+
+  std::vector<NodePtr> children(type->num_children());
+  for (int i = 0; i < type->num_children(); i++) {
+    RETURN_NOT_OK(FieldToNode(type->child(i), properties, &children[i]));
+  }
+
+  *out = GroupNode::Make(name, repetition, children);
+  return Status::OK();
+}
+
+Status FieldToNode(const std::shared_ptr<Field>& field,
+    const WriterProperties& properties, NodePtr* out) {
+  LogicalType::type logical_type = LogicalType::NONE;
+  ParquetType::type type;
+  Repetition::type repetition = Repetition::REQUIRED;
+  if (field->nullable) { repetition = Repetition::OPTIONAL; }
+  int length = -1;
+
+  switch (field->type->type) {
+    // TODO:
+    // case ArrowType::NA:
+    // break;
+    case ArrowType::BOOL:
+      type = ParquetType::BOOLEAN;
+      break;
+    case ArrowType::UINT8:
+      type = ParquetType::INT32;
+      logical_type = LogicalType::UINT_8;
+      break;
+    case ArrowType::INT8:
+      type = ParquetType::INT32;
+      logical_type = LogicalType::INT_8;
+      break;
+    case ArrowType::UINT16:
+      type = ParquetType::INT32;
+      logical_type = LogicalType::UINT_16;
+      break;
+    case ArrowType::INT16:
+      type = ParquetType::INT32;
+      logical_type = LogicalType::INT_16;
+      break;
+    case ArrowType::UINT32:
+      if (properties.version() == ::parquet::ParquetVersion::PARQUET_1_0) {
+        type = ParquetType::INT64;

Review comment:
       @xhochy Can you explain why UINT_32 is not emitted for Parquet version 1.0? There's zero comment and I can't find any explanation otherwise.




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