Function GetColumnParquetInfo

cpp/src/parquet/chunker_internal_test.cc:378–404

using ParquetInfo = std::vector<ColumnInfo>;

ParquetInfo GetColumnParquetInfo(const std::shared_ptr<Buffer>& data, int column_index) {
  // Read the parquet data out of the buffer and get the sizes and lengths of the
  // data pages in given column. We assert on the sizes and lengths of the pages
  // to ensure that the chunking is done correctly.
  ParquetInfo result;

  auto buffer_reader = std::make_shared<BufferReader>(data);
  auto parquet_reader = ParquetFileReader::Open(std::move(buffer_reader));

  auto metadata = parquet_reader->metadata();
  for (int rg = 0; rg < metadata->num_row_groups(); rg++) {
    auto page_reader = parquet_reader->RowGroup(rg)->GetColumnPageReader(column_index);
    ColumnInfo column_info;
    while (auto page = page_reader->NextPage()) {
      if (page->type() == PageType::DATA_PAGE || page->type() == PageType::DATA_PAGE_V2) {
        auto data_page = static_cast<DataPage*>(page.get());
        column_info.page_sizes.push_back(data_page->uncompressed_size());
        column_info.page_lengths.push_back(data_page->num_values());
      } else if (page->type() == PageType::DICTIONARY_PAGE) {
        column_info.has_dictionary_page = true;
      }
    }
    result.push_back(column_info);
  }

  return result;
}

// A git-hunk like side-by-side data structure to represent the differences between two
// vectors of uint64_t values.