I use PG with an alternative materialized views implementation[0] that is pure PlPgSQL and that exposes real tables that can be used to write to in triggers, and where the views can be marked stale too.

This means hand-coding triggers to keep the materializations up to date, or else to mark them as out of date (because maybe some operations would be slow or hard to hand-code triggers for), but this works remarkably well.

As a bonus, I get an update history table that can be used to generate updates to external systems.

In principle one can get the AST for a VIEW's query from the PG catalog and use that generate triggers on the tables it queries to keep it up to date. In practice that's only trivial for some kinds of queries, and I've not written such a tool yet.

[0] https://github.com/twosigma/postgresql-contrib/blob/master/m...