presto-main/src/main/java/io/prestosql/operator/aggregation/state/HyperLogLogStateFactory.java/SingleHyperLogLogState/getEstimatedSize
class SingleHyperLogLogState:        @Override
        public long getEstimatedSize()
        {
            long estimatedSize = INSTANCE_SIZE;
            if (hll != null) {
                estimatedSize += hll.estimatedInMemorySize();
            }
            return estimatedSize;
        }