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  • 多列单个索引和联合索引的区别

    利用spring boot 构建了200w的数据记录

    package com.example.demo.init;

    import com.example.demo.dao.StudentDao;
    import com.example.demo.model.StudentEbo;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.CommandLineRunner;
    import org.springframework.core.annotation.Order;
    import org.springframework.stereotype.Component;

    import java.util.ArrayList;
    import java.util.List;

    /**
    * @author duanxiaoqiu
    * @Date 2019-06-17 20:12
    **/
    @Slf4j
    @Order(value = 0)
    @Component
    public class initData implements CommandLineRunner {

    @Autowired
    private StudentDao studentDao;

    @Override
    public void run(String... args) throws Exception {
    log.info("=======init=======");
    long start = System.currentTimeMillis();
    List<StudentEbo> studentEbos = new ArrayList<>();
    int num = 0;
    for (int i = 0; i < 2000000; i++) {
    StudentEbo studentEbo = new StudentEbo();
    studentEbo.setName("xq" + i);
    studentEbo.setColor("color" + i);
    studentEbo.setSize("size" + i);
    studentEbos.add(studentEbo);
    num++;
    if (num == 10000) {
    log.info("=======");
    long time=System.currentTimeMillis();
    studentDao.insertByBatch(studentEbos);
    log.info("==time:{}===",System.currentTimeMillis()-time);
    studentEbos.clear();
    num = 0;
    }
    }
    if (studentEbos != null && studentEbos.size() > 0) {
    studentDao.insertByBatch(studentEbos);
    }
    log.info("======cost:{}======", System.currentTimeMillis() - start);
    }
    }

    select * from t_student WHERE size='size10001'

    耗时:0.747s

    1.新增索引

    ALTER TABLE `t_student` ADD INDEX `index1` (`size`) USING BTREE ;

    查询耗时:0.248s

    多列索引和联合索引参考:

    https://www.cnblogs.com/musings/p/10890563.html

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  • 原文地址:https://www.cnblogs.com/zgzf/p/11037674.html
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