presto-benchmark/src/main/java/io/prestosql/benchmark/CountAggregationBenchmark.java/CountAggregationBenchmark/createOperatorFactories
class CountAggregationBenchmark:    @Override
    protected List<? extends OperatorFactory> createOperatorFactories()
    {
        OperatorFactory tableScanOperator = createTableScanOperator(0, new PlanNodeId("test"), "orders", "orderkey");
        Metadata metadata = localQueryRunner.getMetadata();
        InternalAggregationFunction countFunction = metadata.getAggregateFunctionImplementation(metadata.resolveFunction(QualifiedName.of("count"), ImmutableList.of()));
        AggregationOperatorFactory aggregationOperator = new AggregationOperatorFactory(1, new PlanNodeId("test"), Step.SINGLE, ImmutableList.of(countFunction.bind(ImmutableList.of(0), Optional.empty())), false);
        return ImmutableList.of(tableScanOperator, aggregationOperator);
    }