Below you will find pages that utilize the taxonomy term “聚簇索引”
October 8, 2016
一张图让你彻底理解聚簇索引与普通索引的区别[经典]
"\u003cp\u003e[\u003cimg src=\"https://blogstatic.haohtml.com//uploads/2023/09/mysq_index.png\" alt=\"mysq_index\"\u003e][1]\u003c/p\u003e\n\u003cp\u003e下面分析下索引和锁的关系。\n1)delete from msg where id=2;\u003c/p\u003e\n\u003cp\u003e由于id是主键,因此直接锁住整行记录即可。\n\u003cimg src=\"https://blogstatic.haohtml.com//uploads/2023/09/2f67547e0caa0d1ea9bc7cb53966eedf70d49db3.png\" alt=\"\"\u003e 图5\n2)delete from msg where token=’ cvs’;\u003c/p\u003e\n\u003cp\u003e由于token是二级索引,因此首先锁住二级索引(两行),接着会锁住相应主键所对应的记录;\n\u003cimg src=\"https://blogstatic.haohtml.com//uploads/2023/09/e0ac34fd99404ccdee4ab1ec4889f47754ffcd82.png\" alt=\"\"\u003e 图6\n3)delete from msg where message=订单号是多少’;\u003c/p\u003e\n\u003cp\u003emessage没有索引,所以走的是全表扫描过滤。这时表上的各个记录都将添加上X锁。\n\u003cimg src=\"https://blogstatic.haohtml.com//uploads/2023/09/aa9a94c735ec35cfe92cd5eca1015893aad8de58.png\" alt=\"\"\u003e 图7\u003c/p\u003e\n\u003cp\u003e强烈推荐阅读: …\u003c/p\u003e"