presto-main/src/main/java/io/prestosql/operator/aggregation/GenericAccumulatorFactory.java/GenericAccumulatorFactory/OrderingGroupedAccumulator
class GenericAccumulatorFactory:        private OrderingGroupedAccumulator(
                GroupedAccumulator accumulator,
                List<Type> aggregationSourceTypes,
                List<Integer> orderByChannels,
                List<SortOrder> orderings,
                PagesIndex.Factory pagesIndexFactory)
        {
            this.accumulator = requireNonNull(accumulator, "accumulator is null");
            requireNonNull(aggregationSourceTypes, "aggregationSourceTypes is null");
            this.orderByChannels = ImmutableList.copyOf(requireNonNull(orderByChannels, "orderByChannels is null"));
            this.orderings = ImmutableList.copyOf(requireNonNull(orderings, "orderings is null"));
            List<Type> pageIndexTypes = new ArrayList<>(aggregationSourceTypes);
            // Add group id column
            pageIndexTypes.add(BIGINT);
            this.pagesIndex = pagesIndexFactory.newPagesIndex(pageIndexTypes, 10_000);
            this.groupCount = 0;
        }