Mysql 8.0版本合并了腾讯互娱数据库团队的Patch，可以实现秒级添加字段，这个功能可谓是mysql数据库攻城狮的福音，解决了之前5.6，5.7版本添加字段很高的运维成本。

下面是验证mysql8.0版本秒级添加字段的过程

首先用sysbench模拟一张12G左右的大表出来，数据量在5000W

nohup sysbench /usr/share/sysbench/tests/include/oltp_legacy/oltp.lua --mysql-host=10.10.57.205 --mysql-port=3306 --mysql-user=root --mysql-password='Test1234!' --oltp-test-mode=complex --oltp-tables-count=1 --oltp-table-size=50000000 --threads=10 prepare

登录数据库，查看一下sysbench生成的表

mysql> show databases;

+--------------------+

| Database |

+--------------------+

| information_schema |

| mysql |

| performance_schema |

| sbtest |

| sys |

+--------------------+

5 rows in set (0.00 sec)

mysql> use sbtest;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> show tables;

+------------------+

| Tables_in_sbtest |

+------------------+

| sbtest1 |

+------------------+

1 row in set (0.00 sec)

mysql> select count(*) from sbtest1;

+----------+

| count(*) |

+----------+

| 50000000 |

+----------+

1 row in set (17.84 sec)

查看一下表对应的文件大小

[root@cbov10-205 sbtest]# du -sh *

12G sbtest1.ibd

查看测试的表结构

mysql> show create table sbtest1\G;

*************************** 1. row ***************************

Table: sbtest1

Create Table: CREATE TABLE `sbtest1` (

`id` int(10) unsigned NOT NULL AUTO_INCREMENT,

`k` int(10) unsigned NOT NULL DEFAULT '0',

`c` char(120) NOT NULL DEFAULT '',

`pad` char(60) NOT NULL DEFAULT '',

PRIMARY KEY (`id`),

KEY `k_1` (`k`)

) ENGINE=InnoDB AUTO_INCREMENT=50000001 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci MAX_ROWS=1000000

1 row in set (0.00 sec)

在12G大小的表上添加一列，果然是秒级返回

mysql> alter table sbtest1 add column name char(60) not null default '';

Query OK, 0 rows affected (0.18 sec)

Records: 0 Duplicates: 0 Warnings: 0

mysql> show create table sbtest1\G;

*************************** 1. row ***************************

Table: sbtest1

Create Table: CREATE TABLE `sbtest1` (

`id` int(10) unsigned NOT NULL AUTO_INCREMENT,

`k` int(10) unsigned NOT NULL DEFAULT '0',

`c` char(120) NOT NULL DEFAULT '',

`pad` char(60) NOT NULL DEFAULT '',

`name` char(60) NOT NULL DEFAULT '',

PRIMARY KEY (`id`),

KEY `k_1` (`k`)

) ENGINE=InnoDB AUTO_INCREMENT=50000001 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci MAX_ROWS=1000000

1 row in set (0.00 sec)

这个功能特性非常的好用，如果有条件的同学，可以选择将生产的mysql数据库版本升级到mysql8，能减少很多运维工作。