```
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] [                                                                                                                                                                                                                                        <=>               ]
```

if (file_infos.file_names.empty())
    {
        LOG_WARNING(log, "There is a idle table named {}, no files need to parse.", getName());
        return Pipe{};
    }
    auto modified_context = Context::createCopy(local_context);
    auto max_streams_number = std::min<UInt64>(filelog_settings->max_threads, file_infos.file_names.size());
    
    openFilesAndSetPos();
    Pipes pipes;
    pipes.reserve(max_streams_number);
    for (size_t stream_number = 0; stream_number < max_streams_number; ++stream_number)
    {
        pipes.emplace_back(std::make_shared<FileLogSource>(
            *this,
            metadata_snapshot,
            modified_context,
            column_names,
            getMaxBlockSize(),
            getPollTimeoutMillisecond(),
            stream_number,
            max_streams_number));
    }
    return Pipe::unitePipes(std::move(pipes));
}
void StorageFileLog::increaseStreams()
{
    running_streams += 1;
}
void StorageFileLog::reduceStreams()