presto-hive/src/main/java/io/prestosql/plugin/hive/statistics/MetastoreHiveStatisticsProvider.java/MetastoreHiveStatisticsProvider/getPartitionRowCount
class MetastoreHiveStatisticsProvider:    private static OptionalDouble getPartitionRowCount(String partitionName, Map<String, PartitionStatistics> statistics)
    {
        PartitionStatistics partitionStatistics = statistics.get(partitionName);
        if (partitionStatistics == null) {
            return OptionalDouble.empty();
        }
        OptionalLong rowCount = partitionStatistics.getBasicStatistics().getRowCount();
        if (rowCount.isPresent()) {
            verify(rowCount.getAsLong() >= 0, "rowCount must be greater than or equal to zero");
            return OptionalDouble.of(rowCount.getAsLong());
        }
        return OptionalDouble.empty();
    }