MySQL 测试Mybatis 中CASE WHEN 和普通foreach update 批量更新单个字段性能：

Java

2024-3-19 16:43

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123 字

3 分钟

MySQL 从hashmap 批量update Redis缓存+定时任务实现

测试代码
List<Info> infos = new ArrayList<>();
        for (int i = 1; i < 1000; i++) {
            infos.add(new Info(String.valueOf(i), String.valueOf(i), i + "0", new Time(System.currentTimeMillis()), new Time(System.currentTimeMillis())));
        }
        long begin = System.currentTimeMillis();
        System.err.println("数据生成完毕，准备修改  使用CASE WHEN 语法：");
        System.err.println(infoMapper.updateBatch(infos));
//        System.out.println(infos);
        System.err.printf("总用时：%s ms\n", System.currentTimeMillis() - begin);

注意 MySQL 要支持执行多条SQL语句请在url链接中加入配置：url: jdbc:mysql://localhost:3306/library?allowMultiQueries=true

使用case when 批量更新
<update id="updateBatch">-- noinspection SqlNoDataSourceInspectionForFile
        UPDATE info
        SET seat = CASE card
        <foreach collection="list" item="item" separator=" ">
            WHEN #{item.card} THEN #{item.seat}
        </foreach>
        ELSE seat
        END
        WHERE card IN
        <foreach collection="list" item="item" open="(" close=")" separator=",">
            #{item.card}
        </foreach>
    </update>

使用 普通foreach 循环更新
<update id="updateBatchByForEach">
        <foreach collection="list" item="item">
            UPDATE info
            set seat = #{item.seat}
            where card = #{item.card};
        </foreach>
    </update>

1万条数据测试

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Excellent performance comparison! CASE WHEN is typically 3-5x faster for batch updates since it executes as a single statement. Just like how 2jl legit platforms optimize database queries for real-time gaming, proper SQL batching significantly reduces connection overhead. Consider adding prepared statement caching for even better results at scale.
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