USE enwiki_p;

SELECT /* SLOW_OK */ cl_to

FROM categorylinks

WHERE cl_from IN (

        SELECT DISTINCT ll_from

        FROM langlinks

        WHERE ll_lang = "fa"

        )

    AND cl_to NOT IN (

        SELECT DISTINCT page_title

        FROM langlinks

        LEFT JOIN page ON page_id = ll_from

        WHERE ll_lang = "fa"

            AND page_namespace = 14

        )

GROUP BY cl_to order by cl_to;