Any relational database design tool written in Python

[metaperl]

Hello,

I am wondering if I overlooked such a tool at freshmeat, sf.net, and
cheeseshop and google.  I prefer Python, so that I can patch and
upgrade it. Which also means I prefer opensource over commercial.

I am hoping for something that can create database deltas.  I am sort
of divided over the logical versus physical modeling issue.

While I am looking for something fairly graphical like dbSketch or
dbWrench, I am pretty impressed with Django's built-in ORM's ability to
create and update databases.