mysql数据库索引 基础：图论 https://blog.csdn.net/qq_30796379/article/details/80152350 B-Tree和B+Tree https://www.cnblogs.com/coder2012/p/3330311.html https://www.cnblogs.com/dongguacai/p/7239599.html 参考：https://blog.csdn.net/waeceo/article/details/78702584