db migrations on heroku. Docs: https://devcenter.heroku.com/articles/upgrade-heroku-postgres-with-pgbackups

db.sh

# add new database to addons before running this

# fill in the blank
# eg. DBNAME=HEROKU_POSTGRESQL_ROSE <- new Database
DBNAME=HEROKU_POSTGRESQL_ROSE

heroku maintenance:on
heroku scale web=0
heroku pgbackups:capture --expire

# prompts for confirmation
heroku pgbackups:restore $DBNAME

heroku pg:promote $DBNAME
heroku maintenance:off
heroku scale web=2


# remove old database