This query does not show realtime metrics:

```
INSERT INTO wikistat 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,
    CAST(values[3], 'UInt64') AS hits
FROM s3('https://....s3.eu-central-1.amazonaws.com/wikistat/original/*.gz', '...', '...', LineAsString, auto)
WHERE length(values) >= 3
```

Although this query does:

```
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,
    CAST(values[3], 'UInt64') AS hits
FROM s3('https://....s3.eu-central-1.amazonaws.com/wikistat/original/*.gz', '...', '...', LineAsString, auto)
WHERE length(values) >= 3
```

I also was not able to cancel the first query.
{
public:
    explicit Impl(const std::vector<String> & keys_) : keys(keys_), keys_iter(keys.begin())
    {
    }
    String next()
    {
        std::lock_guard lock(mutex);
        if (keys_iter == keys.end())
            return "";
        auto key = *keys_iter;
        ++keys_iter;
        return key;
    }
private:
    std::mutex mutex;
    Strings keys;
    Strings::iterator keys_iter;
};
StorageS3Source::KeysIterator::KeysIterator(const std::vector<String> & keys_) : pimpl(std::make_shared<StorageS3Source::KeysIterator::Impl>(keys_))