lib/slugged/caching.rb
def globally_cache_slug
      return unless send(:"#{self.cached_slug_column}_changed?")
      value = self.to_slug
      self.class.cache_slug_lookup!(value, self) if value.present?
      unless use_slug_history
        value = send(:"#{self.cached_slug_column}_was")
        self.class.cache_slug_lookup!(value, nil)
      end
    end
def globally_cache_slug
      return unless send(:"#{self.cached_slug_column}_changed?")
      value = self.to_slug
      self.class.cache_slug_lookup!(value, self) if value.present?
      unless use_slug_history
        value = send(:"#{self.cached_slug_column}_was")
        self.class.cache_slug_lookup!(value, nil)
      end
    end
Automatically called in after_save, will cache this records id
 with to match the current records slug / scope