presto-orc/src/main/java/io/prestosql/orc/OrcWriteValidation.java/CountStatisticsBuilder/addBlock
class CountStatisticsBuilder:        @Override
        public void addBlock(Type type, Block block)
        {
            for (int position = 0; position < block.getPositionCount(); position++) {
                if (!block.isNull(position)) {
                    rowCount++;
                }
            }
        }