presto-main/src/main/java/io/prestosql/operator/aggregation/GenericAccumulatorFactory.java/GenericAccumulatorFactory/OrderingAccumulator
class GenericAccumulatorFactory:        private OrderingAccumulator(
                Accumulator accumulator,
                List<Type> aggregationSourceTypes,
                List<Integer> orderByChannels,
                List<SortOrder> orderings,
                PagesIndex.Factory pagesIndexFactory)
        {
            this.accumulator = requireNonNull(accumulator, "accumulator is null");
            this.orderByChannels = ImmutableList.copyOf(requireNonNull(orderByChannels, "orderByChannels is null"));
            this.orderings = ImmutableList.copyOf(requireNonNull(orderings, "orderings is null"));
            this.pagesIndex = pagesIndexFactory.newPagesIndex(aggregationSourceTypes, 10_000);
        }