Tagging.where(taggable_type: 'Discussion').pluck(:taggable_id).uniq.each do |discussion_id|
      tag_ids = Tagging.where(taggable_id: discussion_id, taggable_type: 'Discussion').pluck(:tag_id)
      names = Tag.where(id: tag_ids).pluck(:name)
      if d = Discussion.find_by(id: discussion_id)
        group_ids.push d.group_id