Redis 缓存同步至数据库时的 N+1 问题

foreach ($dates as $user_id => $actived_at) {
    // 会将 `user_1` 转换为 1
    $user_id = str_replace($this->field_prefix, '', $user_id);

    // 只有当用户存在时才更新到数据库中
    if ($user = $this->find($user_id)) {
        $user->last_actived_at = $actived_at;
        $user->save();
    }
}Copy

...
use DB;
...
public function syncUserActivedAt() {
    ...
    $data = Redis::hGetAll($hash);  //从 Redis 中获取所有哈希表里的数据
    $this->batchUpdate($data);
    ...
}

private function batchUpdate($data) {
    $sql = 'UPDATE `users` SET last_active_at=CASE id';
    foreach ($data as $key => $activeTime) {
        $user_id = str_replace($this->fieldPrefix, '', $key);   //将user_1转为1
        $sql .= ' WHEN '.$user_id.' THEN "'.$activeTime.'"';
    }
    $sql .= ' ELSE last_active_at END';
    DB::update($sql);
}Copy