message: Correctly negate comparison type of join operator if children are switched
diff: @@ -684,6 +684,10 @@ pair<RelationSet*, unique_ptr<LogicalOperator>> JoinOrderOptimizer::GenerateJoin
  cond.left = move(condition->children[left_child]);
  cond.right = move(condition->children[right_child]);
  cond.comparison = condition->type;
  + if (left_child != 0) {
  + // reverse comparison expression if we reverse the order of the children
  + cond.comparison = ComparisonExpression::NegateComparisionExpression(cond.comparison);
  + }
  join->conditions.push_back(move(cond));
  }
  assert(join->conditions.size() > 0);
  