Method GetRecordBatchGenerator

cpp/src/parquet/arrow/reader.cc:1213–1453

};

::arrow::Result<::arrow::AsyncGenerator<std::shared_ptr<::arrow::RecordBatch>>>
FileReaderImpl::GetRecordBatchGenerator(std::shared_ptr<FileReader> reader,
                                        const std::vector<int> row_group_indices,
                                        const std::vector<int> column_indices,
                                        ::arrow::internal::Executor* cpu_executor,
                                        int64_t rows_to_readahead) {
  RETURN_NOT_OK(BoundsCheck(row_group_indices, column_indices));
  if (rows_to_readahead < 0) {
    return Status::Invalid("rows_to_readahead must be >= 0");
  }
  if (reader_properties_.pre_buffer()) {
    BEGIN_PARQUET_CATCH_EXCEPTIONS
    reader_->PreBuffer(row_group_indices, column_indices, reader_properties_.io_context(),
                       reader_properties_.cache_options());
    END_PARQUET_CATCH_EXCEPTIONS
  }
  ::arrow::AsyncGenerator<RowGroupGenerator::RecordBatchGenerator> row_group_generator =
      RowGroupGenerator(::arrow::internal::checked_pointer_cast<FileReaderImpl>(reader),
                        cpu_executor, row_group_indices, column_indices,
                        rows_to_readahead);
  ::arrow::AsyncGenerator<std::shared_ptr<::arrow::RecordBatch>> concatenated =
      ::arrow::MakeConcatenatedGenerator(std::move(row_group_generator));
  WRAP_ASYNC_GENERATOR(std::move(concatenated));
  return concatenated;
}

Status FileReaderImpl::GetColumn(int i, FileColumnIteratorFactory iterator_factory,
                                 std::unique_ptr<ColumnReader>* out) {
  RETURN_NOT_OK(BoundsCheckColumn(i));
  auto ctx = std::make_shared<ReaderContext>();
  ctx->reader = reader_.get();
  ctx->pool = pool_;
  ctx->iterator_factory = iterator_factory;
  ctx->filter_leaves = false;
  ctx->reader_properties = &reader_properties_;
  std::unique_ptr<ColumnReaderImpl> result;
  RETURN_NOT_OK(GetReader(manifest_.schema_fields[i], ctx, &result));
  *out = std::move(result);
  return Status::OK();
}

Result<std::shared_ptr<Table>> FileReaderImpl::ReadRowGroups(
    const std::vector<int>& row_groups, const std::vector<int>& column_indices) {
  RETURN_NOT_OK(BoundsCheck(row_groups, column_indices));

  // PARQUET-1698/PARQUET-1820: pre-buffer row groups/column chunks if enabled
  if (reader_properties_.pre_buffer()) {
    BEGIN_PARQUET_CATCH_EXCEPTIONS
    parquet_reader()->PreBuffer(row_groups, column_indices,
                                reader_properties_.io_context(),
                                reader_properties_.cache_options());
    END_PARQUET_CATCH_EXCEPTIONS
  }

  auto fut = DecodeRowGroups(/*self=*/nullptr, row_groups, column_indices,
                             /*cpu_executor=*/nullptr);
  return fut.MoveResult();
}