Django & DBAs: "Performance problems due to incorrect many-many primary key on many tables"

Extract from a great thread on the django-developper mailing list started by Trey Raymond:

I’m a DB engineer working for Yahoo, and we have a new product using django that I’m onboarding. We see a variety of easily fixed issues, but one major one - there are 21 many-many tables here, yet they have auto increment primary keys

Looking forward to see how it goes !

Star the thread.