Pythonic ORM with support for composite primary/foreign keys?

[Wolfgang Keller]

Hello,

so far it seems to me as if the only ORM module for Python which 
supports composite primary/foreign keys was SQLAlchemy. Which looks a 
little bit "overbloated" for my needs: I "just" need to be able to 
define a "logical model" (à la UML) in Python and have the ORM connect 
to a database (running on PostgreSQL in my case) which uses a 
corresponding (pre-defined) "physical model" as its schema.

Modeling really does look exactly like what I need. Among others, it 
seems to be understandable even for a Clueless Python Scripting 
Dilettant like me. But support for primary keys is not yet completely 
built-in (and tested).

So, is there another ORM module for Python besides SQLAlchemy which 
supports composite porimary (and foreign) keys, and maybe also other 
more "advanced", maybe even some of the PostgreSQL-specific features 
(such as e.g. composite types)?

TIA,

Sincerely,

Wolfgang Keller