我正在here描述的多个环境下运行Heroku应用。我可以在原始的单一环境下运行，但是当我推送到其中一个并运行heroku run rake db:migrate --remote REMOTE_NAME时，我收到Error: Operation timed out - connect(2) (Errno::ETIMEDOUT)形式的错误。
此实例的heroku logs输出如下：
heroku[api]: Starting process with command `rake db:migrate`
heroku[run.9488]: Awaiting client
heroku[run.9488]: Starting process with command `rake db:migrate`
heroku[run.9488]: Error R99 (Platform error) -> Failed to launch the dyno within 10 seconds
heroku[run.9488]: Stopping process with SIGKILL
heroku[run.9488]: Error R13 (Attach error) -> Failed to attach to process
heroku[run.9488]: Process exited with status 128
heroku[run.9488]: State changed from starting to complete
在使用多个部署环境时迁移数据库的正确流程是什么？