1、redis,什么是分布式锁
https://www.jianshu.com/p/a1ebab8ce78a
2、mysql高效插入数据
https://www.cnblogs.com/dailidong/p/7571074.html
3、时间复杂度和空间复杂度
https://blog.csdn.net/haha223545/article/details/93619874
4、sql优化的几种方式
https://blog.csdn.net/qq_38789941/article/details/83744271