if you do rename_column/add/remove in your migration, don't forget to call reset_column_information in the changed class. Otherwise you may have a problem with running migration on an empty DB if you pre-seed data in the migration after change Example:

 class RenameLinkTemplateElementsToSubtemplates < ActiveRecord::Migration
   def self.up
     rename_column :template_elements, :template_id, :sub_template_id
     TemplateElement.reset_column_information()
   end

  def self.down
     rename_column :template_elements, :sub_template_id, :template_id
     TemplateElement.reset_column_information()
   end
end