message: sync commit
diff: @@ -824,7 +824,7 @@ TempResultSet* GeneralEvaluation::rewritingBasedQueryEvaluation(int dep)
  sub_result = new_result;
  }
  - if (!sub_result->results[0].result.empty())
  + if (sub_result->results.empty() || !sub_result->results[0].result.empty())
  {
  for (int j = 0; j < (int)group_pattern->sub_group_pattern.size(); j++)
  if (group_pattern->sub_group_pattern[j].type == QueryTree::GroupPattern::SubGroupPattern::Optional_type)
  @@ -900,6 +900,12 @@ void GeneralEvaluation::getFinalResult(ResultSet &ret_result)
  {
  long t0 = Util::get_cur_time();
  + if (this->temp_result->results.empty())
  + {
  + this->temp_result->results.push_back(TempResult());
  + this->temp_result->results[0].id_varset += this->query_tree.getGroupPattern().group_pattern_resultset_maximal_varset;
  + }
  +
  Varset useful = this->query_tree.getResultProjectionVarset() + this->query_tree.getGroupByVarset();
  if (this->query_tree.checkProjectionAsterisk())
  