SELECT * FROM (
        SELECT id, age, sex, height, weight, attendence_time,
        EXP1.rownum, MOD(INITIAL.rownum-1, CEIL(COUNT(*) OVER () /1000)) AS person_mod
        FROM   (
            SELECT id, age, sex, height, weight, attendence_time,
            ROW_NUMBER() OVER(ORDER  BY attendence_time) AS rownum
            FROM   person p
              WHERE  p.age = :age
        ) INITIAL
    ) MODROW WHERE MODROW.person_mod = 0 OR rownum = (
                                SELECT COUNT(*)
                                FROM   person p
                                WHERE  p.age = :age
                              )