```
ubuntu@ip-172-31-79-147:/opt/downloads$ clickhouse-local --max_threads 8 --query "WITH parseDateTimeBestEffort(extract(_path, 'pageviews-([\\d\\-]+)\\.gz$')) AS time, splitByChar(' ', line) AS values, splitByChar('.', values[1]) AS projects SELECT time, projects[1] AS project, projects[2] AS subproject, values[2] AS path, (values[3])::UInt64 AS hits FROM file('pageviews*.gz', LineAsString) WHERE length(values) >= 3" | pv > /dev/null
^C01GiB 0:01:08 [ 129MiB/s] [                                                                                                                                                                   <=>                                                                                    ]

ubuntu@ip-172-31-79-147:/opt/downloads$ clickhouse-local --max_threads 8 --query "WITH parseDateTimeBestEffort(extract(toLowCardinality(_path), 'pageviews-([\\d\\-]+)\\.gz$')) AS time, splitByChar(' ', line) AS values, splitByChar('.', values[1]) AS projects SELECT time, projects[1] AS project, projects[2] AS subproject, values[2] AS path, (values[3])::UInt64 AS hits FROM file('pageviews*.gz', LineAsString) WHERE length(values) >= 3" | pv > /dev/null
^C46GiB 0:00:48 [ 175MiB/s] [                                                                                                                                                                                                                                        <=>               ]
```

{
    ReadBufferFromFile in(full_name);
    UInt64 _, last_written_pos;
    if (!tryReadIntText(_, in))
    {
        throw Exception(ErrorCodes::CANNOT_READ_ALL_DATA, "Read meta file {} failed", full_name);
    }
    assertChar('\n', in);
    if (!tryReadIntText(last_written_pos, in))
    {
        throw Exception(ErrorCodes::CANNOT_READ_ALL_DATA, "Read meta file {} failed", full_name);
    }
    if (last_written_pos > offset)
        throw Exception(
            ErrorCodes::LOGICAL_ERROR, "Last stored last_written_pos in meta file {} is bigger than current last_written_pos", full_name);
}
size_t StorageFileLog::getMaxBlockSize() const
{
    return filelog_settings->max_block_size.changed ? filelog_settings->max_block_size.value
                                                    : getContext()->getSettingsRef().max_insert_block_size.value;
}
size_t StorageFileLog::getPollMaxBatchSize() const
{
    size_t batch_size = filelog_settings->poll_max_batch_size.changed ? filelog_settings->poll_max_batch_size.value
                                                                      : getContext()->getSettingsRef().max_block_size.value;
    return std::min(batch_size, getMaxBlockSize());
}
size_t StorageFileLog::getPollTimeoutMillisecond() const