I'm more interesting in queries with joins and doing it efficiently, instead of just tracking updates to tables that are modified, and re-rerunning the entire query.

If we think about modern frontends using SQL-based backends, essentially every time we render, its ultimately the result of a tree of SQL queries (queries depend on results of other queries) running in the backend. Our frontend app state is just a tree of materialized views of our database which depend on each other. We've got a bunch of state management libraries that deal with trees but they don't fit so well with relational/graph-like data.

I came across a Postgres proposal for [Incremental View Maintenance][2] which generates a diff against an existing query with the purpose of updating a materialized view. Oracle also has [`FAST REFRESH`][3] for materialized views.

I guess it's relatively easy to do until you start needing joins or traversing graphs/hierarchies - which is why its maybe avoided.

EDIT: [Materialize][1] looks interesting in this space: "Execute streaming SQL Joins" but more focused on the event streams rather than general-purpose DML/OLTP.

[1]: https://github.com/rethinkdb/rethinkdb_rebirth

[2]: https://wiki.postgresql.org/wiki/Incremental_View_Maintenance

[3]: https://docs.oracle.com/database/121/DWHSG/refresh.htm#DWHSG8361

[4]: https://materialize.com/