docs: private ParsedResultAccumulator getBestCostPlanForEphemeralScans(List<StmtEphemeralTableScan> scans) {
          int nextPlanId = m_planSelector.m_planId;
          boolean orderIsDeterministic = true;
          boolean hasSignificantOffsetOrLimit = false;
          String contentNonDeterminismMessage = null;
          for (StmtEphemeralTableScan scan : scans) {
              if (scan instanceof StmtSubqueryScan) {
                  nextPlanId = planForParsedSubquery((StmtSubqueryScan)scan, nextPlanId);
                  // If we can't plan this, then give up.
                  if (((StmtSubqueryScan) scan).getBestCostPlan() == null) {
                      return null;
                  }
              }
              else if (scan instanceof StmtCommonTableScan) {
                  nextPlanId = planForCommonTableQuery((StmtCommonTableScan)scan, nextPlanId);
                  if (((StmtCommonTableScan) scan).getBestCostBasePlan() == null) {
                      return null;
                  }
              }
              else {
                  throw new PlanningErrorException("Unknown scan plan type.");
              }
              orderIsDeterministic = scan.isOrderDeterministic(orderIsDeterministic);
              contentNonDeterminismMessage = scan.contentNonDeterminismMessage(contentNonDeterminismMessage);
              hasSignificantOffsetOrLimit = scan.hasSignificantOffsetOrLimit(hasSignificantOffsetOrLimit);
          }
          // need to reset plan id for the entire SQL
          m_planSelector.m_planId = nextPlanId;
  
          return new ParsedResultAccumulator(orderIsDeterministic,
                                             hasSignificantOffsetOrLimit,
                                             contentNonDeterminismMessage);
      }