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)
