presto-main/src/main/java/io/prestosql/operator/WindowOperator.java/WindowOperator/PagesToPagesIndexes
class WindowOperator:        PagesToPagesIndexes(
                PagesIndexWithHashStrategies pagesIndexWithHashStrategies,
                List<Integer> orderChannels,
                List<SortOrder> ordering)
        {
            this.pagesIndexWithHashStrategies = pagesIndexWithHashStrategies;
            this.orderChannels = orderChannels;
            this.ordering = ordering;
            this.memoryContext = operatorContext.aggregateUserMemoryContext().newLocalMemoryContext(PagesToPagesIndexes.class.getSimpleName());
        }