As a sibling commenter mentioned, it's built on timely dataflow (which is lower-level), but that already has differential dataflow[0] built on top of it by the same authors.
How do they differ?
(btw. I think dataflow is very cool as a computing model (not just timely dataflow), to the point of building OctoSQL[1] around it, so I'm really curious about the details here)
[0]: https://github.com/TimelyDataflow/differential-dataflow