presto-main/src/main/java/io/prestosql/operator/aggregation/builder/MergingHashAggregationBuilder.java/MergingHashAggregationBuilder/shouldProduceOutput
class MergingHashAggregationBuilder:    private boolean shouldProduceOutput(long memorySize)
    {
        return (memoryLimitForMerge > 0 && memorySize > memoryLimitForMerge);
    }