SELECT u.id,
       ut.tags,
       COALESCE(NULLIF(l1.first_name, ''), NULLIF(l2.first_name, ''), NULLIF(l3.first_name, ''))    AS first_name,
       COALESCE(NULLIF(l1.last_name, ''), NULLIF(l2.last_name, ''), NULLIF(l3.last_name, ''))       AS last_name,
       COALESCE(NULLIF(l1.middle_name, ''), NULLIF(l2.middle_name, ''), NULLIF(l3.middle_name, '')) AS middle_name
FROM user u
         LEFT JOIN (SELECT user_id, array_agg(tag) AS tags
                    FROM user_tag
                    WHERE user_id = 6
                    GROUP BY user_id) ut
                   ON u.id = ut.user_id
         LEFT JOIN user_i18n l1 ON u.id = l1.id AND l1.lang = 'RU'
         LEFT JOIN user_i18n l2 ON u.id = l2.id AND l2.lang = 'RU_AUTO'
         LEFT JOIN user_i18n l3 ON u.id = l3.id AND l3.lang = 'EN'
WHERE u.id = 6