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