No "ON UPDATE CASCADE" available?

[Markus-]

I just discovered Pony ORM and as reading through the documentation I stumbled across the missing "ON UPDATE CASCADE" part. I found "ON DELETE CASCADE" part, but not for the UPDATE.

So I have multiple tables with a explicit defined primary key which is not an integer and so it could be changed regulary.

How does Pony handle this in a relationship?

For example I have a table which has the primary key role_level = PrimaryKey(str) and a table ProductRoles which has a Set('RoleLevel')

Regards
Markus