presto-main/src/main/java/io/prestosql/cost/CostCalculatorUsingExchanges.java/CostCalculatorUsingExchanges/visitAssignUniqueId
class CostCalculatorUsingExchanges:        @Override
        public PlanCostEstimate visitAssignUniqueId(AssignUniqueId node, Void context)
        {
            LocalCostEstimate localCost = LocalCostEstimate.ofCpu(getStats(node).getOutputSizeInBytes(ImmutableList.of(node.getIdColumn()), types));
            return costForStreaming(node, localCost);
        }