presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/thrift/ThriftMetastoreUtil.java/ThriftMetastoreUtil/getTotalSizeInBytes
class ThriftMetastoreUtil:    private static OptionalLong getTotalSizeInBytes(OptionalDouble averageColumnLength, OptionalLong rowCount, OptionalLong nullsCount)
    {
        if (averageColumnLength.isPresent() && rowCount.isPresent() && nullsCount.isPresent()) {
            long nonNullsCount = rowCount.getAsLong() - nullsCount.getAsLong();
            if (nonNullsCount < 0) {
                return OptionalLong.empty();
            }
            return OptionalLong.of(round(averageColumnLength.getAsDouble() * nonNullsCount));
        }
        return OptionalLong.empty();
    }