code: func altSet(db *sql.DB, key, value string) error {
  	r, err := db.Query("SELECT replaceinto($1, $2)", key, value)
  	if err != nil {
  		return err
  	}
  	return r.Close()
  }
docs: // postgres does not have REPLACE INTO (upsert), so we use that custom
  // one for Set operations instead