SELECT bl_resp.id AS "bl_resp.id",bl_resp.autor AS "bl_resp.autor",bl_resp.idAutor AS "bl_resp.idAutor",bl_resp.text AS "bl_resp.text",bl_resp.fecha AS "bl_resp.fecha",bl_resp.web AS "bl_resp.web",yosum85_foro.foro_users.username AS "yosum85_foro.foro_users.username" FROM bl_resp LEFT JOIN yosum85_foro.foro_users ON bl_resp.idAutor=yosum85_foro.foro_users.user_id WHERE bl_resp.postid=1970 ORDER BY bl_resp.fecha ASC LIMIT 0,50 no es una consulta correcta(Out of sort memory, consider increasing server sort buffer size)