php，mysql_query(）语句，提示内存溢出

php后台接口，将两个表进行联合查询，使用union语句，在phpmyadmin中执行没有问题，
但是用postman进行测试时，提示内存溢出，有没有不使用ini_set的方法，解决这个问题，我试着unset了
几个变量，还是不行
$recommend = 1;

 $check_status = 2;
    $art_act_reslut = mysql_query(
    "SELECT * FROM (
    SELECT 
    publish_time,
    article_id as id,
    user_id as user_brand_id,
    article_text as text, 
    article_thumbs as thumds_person_num,
    sort_weight,
    '' as title,
    article_comment_number as article_comment_number FROM article 
    WHERE recommend = '$recommend' and check_status = '$check_status' and publish_time > '$timestamp'
    UNION
    SELECT 
    publish_time,
    activity_id as id,
    brand_id as user_beand_id,
    activity_content as text,
    join_persons as thumds_person_num,
    sort_weight,
    activity_title as title,
    '' as article_comment_number FROM activity
    WHERE recommend = '$recommend' and check_status = '$check_status' and publish_time > '$timestamp') stain 
    ORDER BY stain.publish_time DESC, stain.sort_weight DESC");

    unset($recommend);
    unset($check_status);
    //赋值到cards
    for($i=0;$i<20;$i++) {
        $cards_arr = array();
        $art_act_reslut_value =  mysql_fetch_assoc($art_act_reslut);    

        //给相应的参数赋值
        $id = $art_act_reslut_value["id"];
        $user_brand_id = $art_act_reslut_value["user_brand_id"];
        $text = $art_act_reslut_value["text"];
        $thumds_person_num = $art_act_reslut_value["thumds_person_num"];
        $article_comment_nummber = $art_act_reslut_value["article_comment_number"];
        $publish_time = $art_act_reslut_value["publish_time"];
        $title = $art_act_reslut_value["title"];
        $sort_weight = $art_act_reslut_value["sort_weight"];

        unset($art_act_reslut_value);

这是错误信息
Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 20 bytes) in /home/fgang/local/apache/htdocs/bimu/interface/get_home_recommand.php on line 102

一般情况下就是条件写错了。跑下explain一目了然