Currently, the extensions patch considers that foreign data wrappers,
foreign servers, and user mapping objects can all be parts of extensions.
This is slightly problematic for pg_dump, where somebody decided to take
a shortcut and not implement user mappings using the full DumpableObject
infrastructure. That could be fixed, but I'm wondering whether it's
worth the trouble. I can see the point of writing an FDW as an
extension but it's a lot harder to see why either foreign server or user
mapping objects would ever be part of an extension. So it might just be
best to remove those two object types from the set that can be managed
by an extension.
Comments?
regards, tom lane