Function main

cpp/examples/parquet/low_level_api/reader_writer2.cc:49–434

const char PARQUET_FILENAME[] = "parquet_cpp_example2.parquet";

int main(int argc, char** argv) {
  /**********************************************************************************
                             PARQUET WRITER EXAMPLE
  **********************************************************************************/
  // parquet::REQUIRED fields do not need definition and repetition level values
  // parquet::OPTIONAL fields require only definition level values
  // parquet::REPEATED fields require both definition and repetition level values
  try {
    // Create a local file output stream instance.
    using FileClass = ::arrow::io::FileOutputStream;
    std::shared_ptr<FileClass> out_file;
    PARQUET_ASSIGN_OR_THROW(out_file, FileClass::Open(PARQUET_FILENAME));

    // Setup the parquet schema
    std::shared_ptr<GroupNode> schema = SetupSchema();

    // Add writer properties
    parquet::WriterProperties::Builder builder;
    builder.compression(parquet::Compression::SNAPPY);
    std::shared_ptr<parquet::WriterProperties> props = builder.build();

    // Create a ParquetFileWriter instance
    std::shared_ptr<parquet::ParquetFileWriter> file_writer =
        parquet::ParquetFileWriter::Open(out_file, schema, props);

    // Append a BufferedRowGroup to keep the RowGroup open until a certain size
    parquet::RowGroupWriter* rg_writer = file_writer->AppendBufferedRowGroup();

    int num_columns = file_writer->num_columns();
    std::vector<int64_t> buffered_values_estimate(num_columns, 0);
    for (int i = 0; i < NUM_ROWS; i++) {
      int64_t estimated_bytes = 0;
      // Get the estimated size of the values that are not written to a page yet
      for (int n = 0; n < num_columns; n++) {
        estimated_bytes += buffered_values_estimate[n];
      }

      // We need to consider the compressed pages
      // as well as the values that are not compressed yet
      if ((rg_writer->total_bytes_written() + rg_writer->total_compressed_bytes() +
           estimated_bytes) > ROW_GROUP_SIZE) {
        rg_writer->Close();
        std::fill(buffered_values_estimate.begin(), buffered_values_estimate.end(), 0);
        rg_writer = file_writer->AppendBufferedRowGroup();
      }

      int col_id = 0;
      // Write the Bool column
      parquet::BoolWriter* bool_writer =
          static_cast<parquet::BoolWriter*>(rg_writer->column(col_id));
      bool bool_value = ((i % 2) == 0) ? true : false;
      bool_writer->WriteBatch(1, nullptr, nullptr, &bool_value);
      buffered_values_estimate[col_id] = bool_writer->estimated_buffered_value_bytes();

      // Write the Int32 column
      col_id++;
      parquet::Int32Writer* int32_writer =
          static_cast<parquet::Int32Writer*>(rg_writer->column(col_id));