I think this is a little bit harsh; you are pointing to one specific query that does not work out of a dataset of 1.6 billion rows exposed live to the internet

I think this is a little bit harsh; you are pointing to one specific query that does not work out of a dataset of 1.6 billion rows exposed live to the internet and could sustain tens of thousands of users concurrently. In any case, we're grateful for the cto of clickhouse to point those things so we can improve the product further. But generalisations such as "the demo does not work at all" is not a fair comment, nor beneficial IMO.