Method GetNext

be/src/exec/union-node.cc:304–347

}

Status UnionNode::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));
  RETURN_IF_CANCELLED(state);
  RETURN_IF_ERROR(QueryMaintenance(state));

  if (to_close_child_idx_ != -1) {
    // The previous child needs to be closed if passthrough was enabled for it. In the non
    // passthrough case, the child was already closed in the previous call to GetNext().
    DCHECK(IsChildPassthrough(to_close_child_idx_));
    DCHECK(!IsInSubplan());
    child(to_close_child_idx_)->Close(state);
    to_close_child_idx_ = -1;
  }

  // Save the number of rows in case GetNext() is called with a non-empty batch, which can
  // happen in a subplan.
  int num_rows_before = row_batch->num_rows();

  if (HasMorePassthrough()) {
    RETURN_IF_ERROR(GetNextPassThrough(state, row_batch));
  } else if (HasMoreMaterialized()) {
    RETURN_IF_ERROR(GetNextMaterialized(state, row_batch));
  } else if (HasMoreConst(state)) {
    RETURN_IF_ERROR(GetNextConst(state, row_batch));
  }

  int num_rows_added = row_batch->num_rows() - num_rows_before;
  DCHECK_GE(num_rows_added, 0);
  if (limit_ != -1 && rows_returned() + num_rows_added > limit_) {
    // Truncate the row batch if we went over the limit.
    num_rows_added = limit_ - rows_returned();
    row_batch->set_num_rows(num_rows_before + num_rows_added);
    DCHECK_GE(num_rows_added, 0);
  }
  IncrementNumRowsReturned(num_rows_added);

  *eos = ReachedLimit() ||
      (!HasMorePassthrough() && !HasMoreMaterialized() && !HasMoreConst(state));

  COUNTER_SET(rows_returned_counter_, rows_returned());
  return Status::OK();
}

Status UnionNode::Reset(RuntimeState* state, RowBatch* row_batch) {
  child_idx_ = 0;