title: Create Sequence In Migration Not Reflected In Schema
body: <p>I have an application that requires a sequence to be present in the database. I have a migration that does the following:</p>
  
  <pre><code>class CreateSequence &lt; ActiveRecord::Migration
    def self.up
      execute "CREATE SEQUENCE sequence"
    end
  
    def self.down
      execute "DROP SEQUENCE sequence"
    end
  end
  </code></pre>
  
  <p>This does not modify the <code>schema.rb</code> and thus breaks <code>rake db:setup</code>. How can I force the schema to include the sequence?</p>
  
  <p>Note: The sequence exists after running <code>rake db:migrate</code>.</p>