presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/thrift/ThriftHiveMetastore.java/ThriftHiveMetastore/getPartitionColumnStatistics
class ThriftHiveMetastore:    private Map<String, Map<String, HiveColumnStatistics>> getPartitionColumnStatistics(
            HiveIdentity identity,
            String databaseName,
            String tableName,
            Set<String> partitionNames,
            List<String> columnNames,
            Map<String, OptionalLong> partitionRowCounts)
    {
        return getMetastorePartitionColumnStatistics(identity, databaseName, tableName, partitionNames, columnNames).entrySet().stream()
                .filter(entry -> !entry.getValue().isEmpty())
                .collect(toImmutableMap(
                        Map.Entry::getKey,
                        entry -> groupStatisticsByColumn(entry.getValue(), partitionRowCounts.getOrDefault(entry.getKey(), OptionalLong.empty()))));
    }