用 force index()指定想要走的索引

一、使用explain工具分析sql

explain select count(id) from person_info_large;

二、修改sql或者尽量让sql走索引

explain select count(id) from person_info_large force index (primary);

用 force index()指定想要走的索引

一、使用explain工具分析sql

explain select count(id) from person_info_large;

二、修改sql或者尽量让sql走索引

explain select count(id) from person_info_large force index (primary);