Upgrade Heroku databse with database copy

gistfile1.txt

There are few things to remember 
1) Before upgrading datbase for safer side create backup or current database.
2) Start manatance on so that in middle there should not save any other record which may loss due to databse upgradation 
3) Look into the heroku plans according to your need you can find it here https://devcenter.heroku.com/articles/heroku-postgres-plans

I am sharing example to upgrade my database from Hobby-basic to Standard0	
heroku maintenance:on
heroku addons:create heroku-postgresql:standard-0

heroku pg:copy DATABASE_URL HEROKU_POSTGRESQL_RED_URL --app sushi

heroku pg:promote HEROKU_POSTGRESQL_RED_URL

heroku maintenance:of