title: migration error switching to postgresql in RoR app
body: <p>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)</p>
  
  <p>this is my database.yml</p>
  
  <pre><code>default: &amp;default
  adapter: sqlite3
  pool: 5
  timeout: 5000
  
  development:
   &lt;&lt;: *default
  database: db/development.sqlite3
  
  
  test: &amp;test
   &lt;&lt;: *default
  database: db/test.sqlite3
  
  production:
   &lt;&lt;: *default
  database: db/production.sqlite3
  
  cucumber:
  &lt;&lt;: *test
  </code></pre>
  
  <p>now, switching to postgresql is </p>
  
  <pre><code>default: &amp;default
  adapter:  postgresql
  encoding: unicode
  pool: 5
  timeout: 5000
  
  development:
   &lt;&lt;: *default
  database: development
  
  
  test: &amp;test
   &lt;&lt;: *default
  database: test
  
  production:
   &lt;&lt;: *default
  database: production
  
  cucumber:
   &lt;&lt;: *test
  </code></pre>
  
  <p>in gemfile I have replace gem 'sqlite3' with gem 'pg'</p>
  
  <p>typing rails db:migrate the error is </p>
  
  <pre><code>ActiveRecord::NoDatabaseError: FATAL:  database "development" does not exist
  </code></pre>