fsaintjacques commented on a change in pull request #7033: URL: https://github.com/apache/arrow/pull/7033#discussion_r417959216
########## File path: cpp/src/arrow/dataset/file_csv.cc ########## @@ -0,0 +1,136 @@ +// 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 "arrow/dataset/file_csv.h" + +#include <algorithm> +#include <memory> +#include <string> +#include <utility> + +#include "arrow/csv/options.h" +#include "arrow/csv/reader.h" +#include "arrow/dataset/dataset_internal.h" +#include "arrow/dataset/file_base.h" +#include "arrow/dataset/filter.h" +#include "arrow/dataset/type_fwd.h" +#include "arrow/dataset/visibility.h" +#include "arrow/result.h" +#include "arrow/type.h" +#include "arrow/util/iterator.h" + +namespace arrow { +namespace dataset { + +using internal::checked_cast; +using internal::checked_pointer_cast; + +static inline Result<csv::ConvertOptions> GetConvertOptions( + const CsvFileFormat& format, const std::shared_ptr<ScanOptions>& scan_options) { + auto options = csv::ConvertOptions::Defaults(); + if (scan_options != nullptr) { + // This is set to true to match behavior with other formats; a missing column + // will be materialized as null. + options.include_missing_columns = true; Review comment: I would expect the FilterAndProjectScanTask to fix this in a more efficient way. ########## File path: cpp/src/arrow/dataset/file_csv.cc ########## @@ -0,0 +1,136 @@ +// 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 "arrow/dataset/file_csv.h" + +#include <algorithm> +#include <memory> +#include <string> +#include <utility> + +#include "arrow/csv/options.h" +#include "arrow/csv/reader.h" +#include "arrow/dataset/dataset_internal.h" +#include "arrow/dataset/file_base.h" +#include "arrow/dataset/filter.h" +#include "arrow/dataset/type_fwd.h" +#include "arrow/dataset/visibility.h" +#include "arrow/result.h" +#include "arrow/type.h" +#include "arrow/util/iterator.h" + +namespace arrow { +namespace dataset { + +using internal::checked_cast; +using internal::checked_pointer_cast; + +static inline Result<csv::ConvertOptions> GetConvertOptions( + const CsvFileFormat& format, const std::shared_ptr<ScanOptions>& scan_options) { + auto options = csv::ConvertOptions::Defaults(); + if (scan_options != nullptr) { + // This is set to true to match behavior with other formats; a missing column + // will be materialized as null. + options.include_missing_columns = true; + + for (const auto& field : scan_options->schema()->fields()) { + options.column_types[field->name()] = field->type(); + options.include_columns.push_back(field->name()); + } + + // FIXME(bkietz) also acquire types of fields materialized but not projected. + for (auto&& name : FieldsInExpression(scan_options->filter)) { + ARROW_ASSIGN_OR_RAISE(auto match, + FieldRef(name).FindOneOrNone(*scan_options->schema())); + if (match.indices().empty()) { + options.include_columns.push_back(std::move(name)); + } + } + } + return options; +} + +static inline csv::ReadOptions GetReadOptions(const CsvFileFormat& format) { + auto options = csv::ReadOptions::Defaults(); + // Multithreaded conversion of individual files would lead to excessive thread + // contention when ScanTasks are also executed in multiple threads, so we disable it + // here. + options.use_threads = false; + return options; +} + +static inline Result<std::shared_ptr<csv::StreamingReader>> OpenReader( + const FileSource& source, const CsvFileFormat& format, + const std::shared_ptr<ScanOptions>& options = nullptr, Review comment: I'd take a ConvertOption instead of a ScanTask. ########## File path: cpp/src/arrow/dataset/file_csv.cc ########## @@ -0,0 +1,136 @@ +// 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 "arrow/dataset/file_csv.h" + +#include <algorithm> +#include <memory> +#include <string> +#include <utility> + +#include "arrow/csv/options.h" +#include "arrow/csv/reader.h" +#include "arrow/dataset/dataset_internal.h" +#include "arrow/dataset/file_base.h" +#include "arrow/dataset/filter.h" +#include "arrow/dataset/type_fwd.h" +#include "arrow/dataset/visibility.h" +#include "arrow/result.h" +#include "arrow/type.h" +#include "arrow/util/iterator.h" + +namespace arrow { +namespace dataset { + +using internal::checked_cast; +using internal::checked_pointer_cast; + +static inline Result<csv::ConvertOptions> GetConvertOptions( + const CsvFileFormat& format, const std::shared_ptr<ScanOptions>& scan_options) { + auto options = csv::ConvertOptions::Defaults(); + if (scan_options != nullptr) { + // This is set to true to match behavior with other formats; a missing column + // will be materialized as null. + options.include_missing_columns = true; + + for (const auto& field : scan_options->schema()->fields()) { + options.column_types[field->name()] = field->type(); + options.include_columns.push_back(field->name()); + } + + // FIXME(bkietz) also acquire types of fields materialized but not projected. + for (auto&& name : FieldsInExpression(scan_options->filter)) { + ARROW_ASSIGN_OR_RAISE(auto match, + FieldRef(name).FindOneOrNone(*scan_options->schema())); + if (match.indices().empty()) { + options.include_columns.push_back(std::move(name)); + } + } + } + return options; +} + +static inline csv::ReadOptions GetReadOptions(const CsvFileFormat& format) { + auto options = csv::ReadOptions::Defaults(); + // Multithreaded conversion of individual files would lead to excessive thread + // contention when ScanTasks are also executed in multiple threads, so we disable it + // here. + options.use_threads = false; + return options; +} + +static inline Result<std::shared_ptr<csv::StreamingReader>> OpenReader( + const FileSource& source, const CsvFileFormat& format, + const std::shared_ptr<ScanOptions>& options = nullptr, + MemoryPool* pool = default_memory_pool()) { + ARROW_ASSIGN_OR_RAISE(auto input, source.Open()); + + auto reader_options = GetReadOptions(format); + const auto& parse_options = format.parse_options; + ARROW_ASSIGN_OR_RAISE(auto convert_options, GetConvertOptions(format, options)); + auto maybe_reader = csv::StreamingReader::Make(pool, std::move(input), reader_options, + parse_options, convert_options); + if (!maybe_reader.ok()) { + return maybe_reader.status().WithMessage("Could not open CSV input source '", + source.path(), "': ", maybe_reader.status()); + } + + return std::move(maybe_reader).ValueOrDie(); +} + +/// \brief A ScanTask backed by an Csv file. +class CsvScanTask : public ScanTask { + public: + CsvScanTask(std::shared_ptr<const CsvFileFormat> format, FileSource source, + std::shared_ptr<ScanOptions> options, std::shared_ptr<ScanContext> context) + : ScanTask(std::move(options), std::move(context)), + format_(std::move(format)), + source_(std::move(source)) {} + + Result<RecordBatchIterator> Execute() override { + ARROW_ASSIGN_OR_RAISE(auto reader, + OpenReader(source_, *format_, options(), context()->pool)); + return IteratorFromReader(std::move(reader)); + } + + private: + std::shared_ptr<const CsvFileFormat> format_; + FileSource source_; +}; + +Result<bool> CsvFileFormat::IsSupported(const FileSource& source) const { + RETURN_NOT_OK(source.Open().status()); Review comment: Can't you let OpenReader fail? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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