bkietz commented on a change in pull request #7033: URL: https://github.com/apache/arrow/pull/7033#discussion_r418111903
########## 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: This is just to stop conversion from erroring if a column is projected but absent from the file. Another way to handle this would be: restrict include_colums to columns present in the file then let the projector handle the rest as you say, but that would require knowledge of the file's columns which we don't have at this stage ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
