neilechao commented on code in PR #45375: URL: https://github.com/apache/arrow/pull/45375#discussion_r2025232060
########## cpp/src/parquet/arrow/variant.h: ########## @@ -0,0 +1,70 @@ +// 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 <stdexcept> +#include <string> + +#include "arrow/extension_type.h" +#include "parquet/platform.h" + +namespace parquet::arrow { + +/// EXPERIMENTAL: Variant is not yet fully supported. +/// +/// Variant supports semi-structured objects that can be composed of +/// primitives, arrays, and objects, which can be queried by path. +/// An unshredded variant contains two binaries, one for the metadata and +/// one for the value. +/// +/// To read more about variant encoding, see the variant encoding spec at +/// https://github.com/apache/parquet-format/blob/master/VariantEncoding.md +class PARQUET_EXPORT VariantExtensionType : public ::arrow::ExtensionType { + public: + explicit VariantExtensionType(const std::shared_ptr<::arrow::DataType>& storage_type) + : ::arrow::ExtensionType(std::move(storage_type)) {} + + std::string extension_name() const override { return "parquet.variant"; } + + bool ExtensionEquals(const ::arrow::ExtensionType& other) const override; + + ::arrow::Result<std::shared_ptr<::arrow::DataType>> Deserialize( + std::shared_ptr<::arrow::DataType> storage_type, + const std::string& serialized_data) const override; + + std::string Serialize() const override; + + std::shared_ptr<::arrow::Array> MakeArray( + std::shared_ptr<::arrow::ArrayData> data) const override; + + static ::arrow::Result<std::shared_ptr<::arrow::DataType>> Make( + std::shared_ptr<::arrow::DataType> storage_type); + + static bool IsSupportedStorageType( + const std::shared_ptr<::arrow::DataType>& storage_type); + + std::shared_ptr<::arrow::Field> metadata_field() const { return children_.at(0); } Review Comment: It is in the Arrow DataType class, but I'm going to remove this since the spec doesn't enforce ordering of the fields. In a followup PR, my plan is to parse the unshredded variant and explicitly set the metadata and value fields (shared_ptrs) and add some testing around their access -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
