presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/storage/OrcStorageManager.java/OrcStorageManager/computeShardStats
class OrcStorageManager:    private List<ColumnStats> computeShardStats(File file)
    {
        try (OrcDataSource dataSource = fileOrcDataSource(orcReaderOptions, file)) {
            OrcReader reader = new OrcReader(dataSource, orcReaderOptions);

            ImmutableList.Builder<ColumnStats> list = ImmutableList.builder();
            for (ColumnInfo info : getColumnInfo(reader)) {
                computeColumnStats(reader, info.getColumnId(), info.getType(), typeManager).ifPresent(list::add);
            }
            return list.build();
        }
        catch (IOException e) {
            throw new PrestoException(RAPTOR_ERROR, "Failed to read file: " + file, e);
        }
    }