I wasn't familiar with StarRocks so thanks for calling attention to it.
It appears to make very different tradeoffs in a number of areas so that makes it a potential useful alternative. In particular transactional DML will make it much more convenient for workloads involving mutation. Plus as you suggested, having a proper Cost-Based Optimizer should make joins more efficient (I find ClickHouse joins to be fine for typical OLAP patterns but they do break down in creative queries...)
It's a bummer though that the deployment model is so complicated. One thing I truly like about ClickHouse is its ability to wring every drop of performance out of a single machine, with a super simple operational model. Being able to scale to a cluster is great but having to start there is Not Great.
