It is great to see that SQL becomes one of the de facto standards of building streaming analytics applications.

Personally I'm not a big fan of KSQL, given that:

(1) KSQL is built on top of Kafka Stream. There are use cases that we don't think Kafka Stream is a good fit. Please see the explanations above

(2) Inventing yet another SQL dialect is a bad idea in practice. Not only it incurs additional learning curves, but more importantly you have few hopes winning in development velocity. Calcite has been used by Flink, Storm, Beam, Dremio, etc. The community is simply way bigger even compared to the total number of engineers in Confluent.

Again this is just my personal take it does not reflect the stands of Uber.