Performance Comparison of Auto‑Increment, UUID, and Random Keys in MySQL

MySQL officially recommends using auto_increment primary keys instead of UUIDs or non‑sequential random IDs; this article investigates why.

Three tables— user_auto_key , user_uuid , and user_random_key —are created, each differing only by the primary key generation strategy. Using Spring Boot, JdbcTemplate, JUnit and Hutool, the author inserts identical data sets into each table and measures insertion time.

The test code (shown below) records execution time for each insert operation using StopWatch and prints the results.

package com.wyq.mysqldemo;

import cn.hutool.core.collection.CollectionUtil;
import com.wyq.mysqldemo.databaseobject.UserKeyAuto;
import com.wyq.mysqldemo.databaseobject.UserKeyRandom;
import com.wyq.mysqldemo.databaseobject.UserKeyUUID;
import com.wyq.mysqldemo.diffkeytest.AutoKeyTableService;
import com.wyq.mysqldemo.diffkeytest.RandomKeyTableService;
import com.wyq.mysqldemo.diffkeytest.UUIDKeyTableService;
import com.wyq.mysqldemo.util.JdbcTemplateService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.util.StopWatch;
import java.util.List;

@SpringBootTest
class MysqlDemoApplicationTests {

    @Autowired
    private JdbcTemplateService jdbcTemplateService;

    @Autowired
    private AutoKeyTableService autoKeyTableService;

    @Autowired
    private UUIDKeyTableService uuidKeyTableService;

    @Autowired
    private RandomKeyTableService randomKeyTableService;

    @Test
    void testDBTime() {
        StopWatch stopwatch = new StopWatch("执行sql时间消耗");

        // auto_increment key task
        final String insertSql = "INSERT INTO user_key_auto(user_id,user_name,sex,address,city,email,state) VALUES(?,?,?,?,?,?,?)";
        List
insertData = autoKeyTableService.getInsertData();
        stopwatch.start("自动生成key表任务开始");
        long start1 = System.currentTimeMillis();
        if (CollectionUtil.isNotEmpty(insertData)) {
            boolean insertResult = jdbcTemplateService.insert(insertSql, insertData, false);
            System.out.println(insertResult);
        }
        long end1 = System.currentTimeMillis();
        System.out.println("auto key消耗的时间:" + (end1 - start1));
        stopwatch.stop();

        // UUID key task
        final String insertSql2 = "INSERT INTO user_uuid(id,user_id,user_name,sex,address,city,email,state) VALUES(?,?,?,?,?,?,?,?)";
        List
insertData2 = uuidKeyTableService.getInsertData();
        stopwatch.start("UUID的key表任务开始");
        long begin = System.currentTimeMillis();
        if (CollectionUtil.isNotEmpty(insertData)) {
            boolean insertResult = jdbcTemplateService.insert(insertSql2, insertData2, true);
            System.out.println(insertResult);
        }
        long over = System.currentTimeMillis();
        System.out.println("UUID key消耗的时间:" + (over - begin));
        stopwatch.stop();

        // Random long key task
        final String insertSql3 = "INSERT INTO user_random_key(id,user_id,user_name,sex,address,city,email,state) VALUES(?,?,?,?,?,?,?,?)";
        List
insertData3 = randomKeyTableService.getInsertData();
        stopwatch.start("随机的long值key表任务开始");
        Long start = System.currentTimeMillis();
        if (CollectionUtil.isNotEmpty(insertData)) {
            boolean insertResult = jdbcTemplateService.insert(insertSql3, insertData3, true);
            System.out.println(insertResult);
        }
        Long end = System.currentTimeMillis();
        System.out.println("随机key任务消耗时间:" + (end - start));
        stopwatch.stop();

        String result = stopwatch.prettyPrint();
        System.out.println(result);
    }
}

Results show that with about 1.3 million existing rows, inserting 100 k new rows, the auto_increment key is fastest, the random key is slower, and UUID is the slowest; performance degrades sharply for UUID as data volume grows.

Analysis of InnoDB index structures explains that auto_increment keys are sequential, leading to minimal page splits, high cache locality, and efficient B‑tree inserts, whereas UUIDs are random, causing frequent page splits, random I/O, and fragmentation.

The article also discusses drawbacks of auto_increment keys, such as exposing business growth information and lock contention under high concurrency.

Conclusion: for InnoDB tables, use sequential auto_increment primary keys whenever possible to achieve better insert performance and index efficiency.