While trying to work with django-planet with MySQL I've encountered two problems:
The Blog model requires the "url" will be both unique and with max_length of 1024. In MySQL this is not possible. URLFields (or actually any char field) can be unique only if it's 256 characters or less.
The second problem is that mysql limits prefix support to 767, and planet requires more. I don't understand this completely but this is documented here: http://dev.mysql.com/doc/refman/5.1/en/create-index.html
search for 767
Blog model url attribute hasn't any given max_length. So, by default, it will use max_length=200. See http://docs.djangoproject.com/en/1.2/ref/models/fields/#urlfield
Are you sure you're using my django-planet? It seems you are suing someone else's fork.
I have the same exact issue; I don't know what to do? I have copied your model into my planet app and still no good news.... please have a look
It's the Post model that has a URLField with max_length=200, changing it wouldn't be enough as the migrations would still be trying to create a broken field in 0001_initial.py