我有一个从数据库返回的结果集。如何使用wp\\u缓存来加快速度？

function bb_attachments_cache() {
    global $wp, $bp, $wpdb, $posts, $bb_attachments, $bb_attachments_cache, $bbdb;


    $all_posts_query = "SELECT `post_id` FROM $bbdb->posts";
    $posts = $bbdb->get_results( $all_posts_query );
    foreach ($posts as $post)  {
        $bb_attachments_cache[$post->post_id] = array();
    }

    $sql = "SELECT 
        bba.id,
        bba.time,
        bba.post_id,
        bba.user_id,
        bba.user_ip,
        bba.status,
        bba.downloads,
        bba.size,
        bba.ext,
        bba.mime,
        bba.filename
    FROM bb_posts bbp
    JOIN bb_attachments bba
    ON bba.post_id = bbp.post_id
    ORDER BY id DESC";

    $attachments = $wpdb->get_results($sql);

    if ($attachments){

        foreach ($results as $result){
            $bb_attachments_cache[$result->post_id][$result->id] = $result;
        }
        unset($attachments);

    }

}

如果附件表有任何更新，我想设置缓存对象。我使用wordpress 3.1，并安装了一个缓存插件。