presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/SemiTransactionalHiveMetastore.java/UpdateStatisticsOperation/updateStatistics
class UpdateStatisticsOperation:        private PartitionStatistics updateStatistics(PartitionStatistics currentStatistics)
        {
            return merge ? merge(currentStatistics, statistics) : statistics;
        }