It's used in production by many thousands of companies at this point. The ClickHouse Inc numbers are just a fraction of the total users.
p.s., It's also possible to break ClickHouse as you demonstrated. It used to be a lot easier.
p.s., It's also possible to break ClickHouse as you demonstrated. It used to be a lot easier.
When you use INSERT ... SELECT in ClickHouse you do need to pay attention to the generated table partitions, as they coexist in memory before flushing to storage. The usual approach is to break up the insert into chunks so you can control how many parts are generated or to adjust the partitioning in the target table.
It's possible the problem might be somehow related to this behavior but that's just conjecture. It's usually pretty easy to work around. Meanwhile if it's a bug it will probably get fixed quickly.