Method ReadBatch

cpp/src/arrow/adapters/orc/adapter.cc:469–494

  }

  Result<std::shared_ptr<RecordBatch>> ReadBatch(const liborc::RowReaderOptions& opts,
                                                 const std::shared_ptr<Schema>& schema,
                                                 int64_t nrows) {
    std::unique_ptr<liborc::RowReader> row_reader;
    std::unique_ptr<liborc::ColumnVectorBatch> batch;
    std::unique_ptr<RecordBatchBuilder> builder;

    ORC_BEGIN_CATCH_NOT_OK
    row_reader = reader_->createRowReader(opts);
    batch = row_reader->createRowBatch(std::min(nrows, kReadRowsBatch));

    ARROW_ASSIGN_OR_RAISE(builder, RecordBatchBuilder::Make(schema, pool_, nrows));
    // The top-level type must be a struct to read into an arrow table
    const auto& struct_batch = checked_cast<liborc::StructVectorBatch&>(*batch);

    const liborc::Type& type = row_reader->getSelectedType();
    while (row_reader->next(*batch)) {
      for (int i = 0; i < builder->num_fields(); i++) {
        RETURN_NOT_OK(AppendBatch(type.getSubtype(i), struct_batch.fields[i], 0,
                                  batch->numElements, builder->GetField(i)));
      }
    }
    ORC_END_CATCH_NOT_OK

    return builder->Flush();
  }

  Status Seek(int64_t row_number) {
    ARROW_RETURN_IF(row_number >= NumberOfRows(),