text: SELECT
  	CONCAT('Comment', '-', comments.id) AS id,
  	comments.body AS body,
  	'Comment' AS contentable_type,
  	comments.id AS contentable_id
  FROM
  	comments
  UNION
  SELECT
  	CONCAT('Post', '-', posts.id) AS id,
  	posts.body AS body,
  	'Post' AS contentable_type,
  	posts.id AS contentable_id
  FROM
  	posts
  