message: Enable parallel execution of perfect aggregate ht
diff: @@ -168,6 +168,14 @@ void Pipeline::Schedule() {
  }
  break;
  }
  + case PhysicalOperatorType::PERFECT_HASH_GROUP_BY: {
  + // perfect hash aggregate can always be parallelized
  + if (ScheduleOperator(sink->children[0].get())) {
  + // all parallel tasks have been scheduled: return
  + return;
  + }
  + break;
  + }
  case PhysicalOperatorType::HASH_GROUP_BY: {
  auto &hash_aggr = (PhysicalHashAggregate &)*sink;
  if (!hash_aggr.all_combinable) {
  