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

{
        std::lock_guard lock(mutex);
        return nextAssumeLocked();
    }
private:
    String nextAssumeLocked()
    {
        if (buffer_iter != buffer.end())
        {
            auto answer = *buffer_iter;
            ++buffer_iter;
            return answer;
        }
        if (is_finished)
            return {};
        fillInternalBufferAssumeLocked();
        return nextAssumeLocked();
    }
    void fillInternalBufferAssumeLocked()
    {
        buffer.clear();
        outcome = client.ListObjectsV2(request);
        if (!outcome.IsSuccess())
            throw Exception(ErrorCodes::S3_ERROR, "Could not list objects in bucket {} with prefix {}, S3 exception: {}, message: {}",
                            quoteString(request.GetBucket()), quoteString(request.GetPrefix()),
                            backQuote(outcome.GetError().GetExceptionName()), quoteString(outcome.GetError().GetMessage()));
        const auto & result_batch = outcome.GetResult().GetContents();