```
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:
    explicit Impl(const std::vector<const String> & uris_, ContextPtr context)
    {
        auto path_and_uri = getPathFromUriAndUriWithoutPath(uris_[0]);
        HDFSBuilderWrapper builder = createHDFSBuilder(path_and_uri.second + "/", context->getGlobalContext()->getConfigRef());
        HDFSFSPtr fs = createHDFSFS(builder.get());
        for (const auto & uri : uris_)
        {
            path_and_uri = getPathFromUriAndUriWithoutPath(uri);
            if (!hdfsExists(fs.get(), path_and_uri.first.c_str()))
                uris.push_back(uri);
        }
        uris_iter = uris.begin();
    }
    String next()