Oracle Database Discussions

Is it possible to create a materialized view with Refresh On Commit that is built from an external table?

I would think the answer is, "No, as there is no way for the external table to signal to the Materialized View that it has been modified," but I would like to be sure before I tell my customer that requested the ability to do this (or, alternatively, learn what Oracle hoops I have to jump through in order to get it to work).

I can create one with Refresh On Demand, so it's not a question of not having permissions to create the materialized view itself.