I'm trying to switch my RoR app from sqlite3 to postgresql, and deploy it on heroku (it seems that heroku doesn't works good with sqlite)

this is my database.yml

```
default: &default
adapter: sqlite3
pool: 5
timeout: 5000

development:
 <<: *default
database: db/development.sqlite3

test: &test
 <<: *default
database: db/test.sqlite3

production:
 <<: *default
database: db/production.sqlite3

cucumber:
<<: *test

```

now, switching to postgresql is 

```
default: &default
adapter:  postgresql
encoding: unicode
pool: 5
timeout: 5000

development:
 <<: *default
database: development

test: &test
 <<: *default
database: test

production:
 <<: *default
database: production

cucumber:
 <<: *test

```

in gemfile I have replace gem 'sqlite3' with gem 'pg'

typing rails db:migrate the error is 

```
ActiveRecord::NoDatabaseError: FATAL:  database "development" does not exist

```