django migration doesn't progress and makes database lock
Open connections will likely stop schema updates. If you can't wait for existing connections to finish, or if your environment is such that long-running connections are used, you may need to halt all connections while you run the update(s).
The downtime, if it's likely to be significant to you, could be mitigated if you have a read-only slave that could stay online. If not, ensuring your site fails over to some sort of error/explanation page/redirect would at least avoid raw failure code responses to requests that come in if downtime for migrations is acceptable.
I've tried to deploy (includes migration) production environment. But my Django migration (like add columns) very often stops and doesn't progress anymore.
I'm working with postgresql 9.3, and I find some reasons of this problem. If postgresql has an active transaction, alter table query is not worked. So until now, restarting postgresql service before migration was a solution, but I think this is a bad idea.
Is there any good idea to progress deploying nicely?