# 利用sysbench生成一張1000W的大表
mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.19  |
+-----------+
1 row in set (0.00 sec)

mysql> select count(*) from sbtest1;
+----------+
| count(*) |
+----------+
| 10000000 |
+----------+

# 增加無默認(rèn)值的列
mysql> alter table sbtest1 add column col1 varchar(20), algorithm=instant;
Query OK, 0 rows affected (0.63 sec)
Records: 0 Duplicates: 0 Warnings: 0

# 增加有默認(rèn)值的列
mysql> alter table sbtest1 add column create_time timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創(chuàng)建時(shí)間', algorithm=instant;
Query OK, 0 rows affected (0.58 sec)
Records: 0 Duplicates: 0 Warnings: 0

# 不顯式指定instant算法
mysql> alter table sbtest1 add column col2 varchar(20);
Query OK, 0 rows affected (0.55 sec)
Records: 0 Duplicates: 0 Warnings: 0

# 設(shè)置列的默認(rèn)值
mysql> alter table sbtest1 alter column col1 set default 'sql',algorithm=instant;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0

# 指定In Place算法添加列，(5.7版本添加列使用該算法)
mysql> alter table sbtest1 add column col_inplace varchar(20),algorithm=inplace;
Query OK, 0 rows affected (1 min 23.30 sec)
Records: 0 Duplicates: 0 Warnings: 0