presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/SemiTransactionalHiveMetastore.java/SemiTransactionalHiveMetastore/updateColumnStatistics
class SemiTransactionalHiveMetastore:    private Map<String, HiveColumnStatistics> updateColumnStatistics(Map<String, HiveColumnStatistics> oldColumnStats, Map<String, HiveColumnStatistics> newColumnStats)
    {
        Map<String, HiveColumnStatistics> result = new HashMap<>(oldColumnStats);
        result.putAll(newColumnStats);
        return ImmutableMap.copyOf(result);
    }