presto-hive/src/main/java/io/prestosql/plugin/hive/PartitionUpdate.java/PartitionUpdate/getStatistics
class PartitionUpdate:    public HiveBasicStatistics getStatistics()
    {
        return new HiveBasicStatistics(fileNames.size(), rowCount, inMemoryDataSizeInBytes, onDiskDataSizeInBytes);
    }