presto-hive/src/main/java/io/prestosql/plugin/hive/HiveMetadata.java/HiveMetadata/getColumnStatistics
class HiveMetadata:    private static Map<ColumnStatisticMetadata, Block> getColumnStatistics(Map<List<String>, ComputedStatistics> statistics, List<String> partitionValues)
    {
        return Optional.ofNullable(statistics.get(partitionValues))
                .map(ComputedStatistics::getColumnStatistics)
                .orElse(ImmutableMap.of());
    }