Method GetNext

be/src/exec/select-node.cc:92–122

}

Status SelectNode::GetNext(RuntimeState* state, RowBatch* row_batch, bool* eos) {
  SCOPED_TIMER(runtime_profile_->total_time_counter());
  ScopedGetNextEventAdder ea(this, eos);
  RETURN_IF_ERROR(ExecDebugAction(TExecNodePhase::GETNEXT, state));
  // start (or continue) consuming row batches from child
  do {
    RETURN_IF_CANCELLED(state);
    RETURN_IF_ERROR(QueryMaintenance(state));
    if (child_row_batch_->num_rows() == 0) {
      // Fetch rows from child if either child row batch has been
      // consumed completely or it is empty.
      RETURN_IF_ERROR(child(0)->GetNext(state, child_row_batch_.get(), &child_eos_));
    }

    SelectPlanNode::CopyRowsFn copy_rows_fn = codegend_copy_rows_fn_.load();
    if (copy_rows_fn != nullptr) {
      copy_rows_fn(this, row_batch);
    } else {
      CopyRows(row_batch);
    }
    COUNTER_SET(rows_returned_counter_, rows_returned());
    *eos = ReachedLimit()
        || (child_row_idx_ == child_row_batch_->num_rows() && child_eos_);
    if (*eos || child_row_idx_ == child_row_batch_->num_rows()) {
      child_row_idx_ = 0;
      child_row_batch_->TransferResourceOwnership(row_batch);
      child_row_batch_->Reset();
    }
  } while (!*eos && !row_batch->AtCapacity());
  return Status::OK();
}

Status SelectNode::Reset(RuntimeState* state, RowBatch* row_batch) {
  child_row_batch_->TransferResourceOwnership(row_batch);