I think the Continuous Computation Language (CCL) name captures the essence of these systems: data flows through the computation/query.
These systems have always had promise but none have found anything but niche adoption. The two most popular use cases seem to be ETL-like dataflows and OLAP style Window queries incrementally updated with streaming data (e.g. computations over stock tick data joined with multiple data sources).
[1] https://en.wikipedia.org/wiki/StreamSQL
[2] https://help.sap.com/doc/PRODUCTION/e1b391d2a3f3439fbab27ed8...