Database migrations on django production
If its not trivial, you should have pre-prod database/ app that mimic the production one. To avoid downtime on production.
From someone who has a django application in a non-trivial production environment, how do you handle database migrations? I know there is south, but it seems like that would miss quite a lot if anything substantial is involved. 
The other two options (that I can think of or have used) is doing the changes on a test database and then (going offline with the app) and importing that sql export. Or, perhaps a riskier option, doing the necessary changes on the production database in real-time, and if anything goes wrong reverting to the back-up.
How do you usually handle your database migrations and schema changes?