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

{
public:
    Impl(ContextPtr context_, const String & uri)
    {
        const auto [path_from_uri, uri_without_path] = getPathFromUriAndUriWithoutPath(uri);
        uris = getPathsList(path_from_uri, uri_without_path, context_);
        for (auto & elem : uris)
            elem = uri_without_path + elem;
        uris_iter = uris.begin();
    }
    String next()
    {
        std::lock_guard lock(mutex);
        if (uris_iter != uris.end())
        {
            auto answer = *uris_iter;
            ++uris_iter;
            return answer;
        }
        return {};
    }
private:
    std::mutex mutex;
    Strings uris;
    Strings::iterator uris_iter;
};
class HDFSSource::URISIterator::Impl