MySQL DDL--MySQL 5.7版本Online DDL操作

主键索引维护

1、新增主键索引

## 可以使用ALGORITHM=INPLACE+LOCK=NONE方式，操作期间允许读写。
ALTER TABLE tb001
ADD PRIMARY KEY (ID),
ALGORITHM = INPLACE;
Query OK, 0 rows affected (22.13 sec)
Records: 0  Duplicates: 0  Warnings: 0

2、官网称如果创建主键索引时需要隐式转换列为NOT NULL则不能使用INPLACE方式(ALGORITHM=INPLACE is not permitted under certain conditions if columns have to be converted to NOT NULL)。
但在MySQL 5.7.19版本中测试发现在允许为NULL的列上创建主键，采用REBUILD INPLACE方式的Online DDL,操作期间允许表并发读写。

2、删除主键索引

## 只能使用ALGORITHM=COPY+LOCK=SHARED方式，操作期间允许读不允许写。
ALTER TABLE tb001
DROP PRIMARY KEY,
ALGORITHM = INPLACE;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Dropping a primary key is not allowed without also adding a new primary key. Try ALGORITHM=COPY.

ALTER TABLE tb001 
DROP PRIMARY KEY, 
ALGORITHM=COPY;
Query OK, 800001 rows affected (20.01 sec)
Records: 800001  Duplicates: 0  Warnings: 0

3、删除并新增主键索引

## 可以使用ALGORITHM=INPLACE+LOCK=NONE方式，操作期间允许读写。
ALTER TABLE TB001 
DROP PRIMARY KEY, 
ADD PRIMARY KEY(C1), 
ALGORITHM=INPLACE, 
LOCK=NONE;
Query OK, 0 rows affected (22.57 sec)
Records: 0  Duplicates: 0  Warnings: 0

4、修改主键列类型

## 只能使用ALGORITHM=COPY+LOCK=SHARED方式，操作期间允许读不允许写。
ALTER TABLE TB001 
CHANGE C1 C1 BIGINT NOT NULL, 
ALGORITHM=INPLACE, LOCK=NONE;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.

ALTER TABLE TB001 
CHANGE C1 C1 BIGINT NOT NULL, 
ALGORITHM=COPY, LOCK=NONE;
ERROR 1846 (0A000): LOCK=NONE is not supported. Reason: COPY algorithm requires a lock. Try LOCK=SHARED.

ALTER TABLE TB001 
CHANGE C1 C1 BIGINT NOT NULL, 
ALGORITHM=COPY, LOCK=SHARED;
Query OK, 799998 rows affected (20.49 sec)
Records: 799998  Duplicates: 0  Warnings: 0

二级索引维护

1、新增二级索引

## 可以使用ALGORITHM=INPLACE+LOCK=NONE方式，操作期间允许读写。
ALTER TABLE TB001 ADD INDEX IDX_C1(C1);
Query OK, 0 rows affected (10.53 sec)
Records: 0  Duplicates: 0  Warnings: 0

2、删除二级索引

## 仅需元数据修改操作，操作时间极短。
ALTER TABLE TB001 DROP INDEX IDX_C1;
Query OK, 0 rows affected (0.13 sec)
Records: 0  Duplicates: 0  Warnings: 0

3、修改二级索引名

## 仅需元数据修改操作，操作时间极短。
ALTER TABLE TB001 
RENAME INDEX IDX_C1 TO IDX_C1_NEW, 
ALGORITHM=INPLACE, LOCK=NONE;
Query OK, 0 rows affected (0.09 sec)
Records: 0  Duplicates: 0  Warnings: 0

4、修改二级索引列类型

## 只能使用ALGORITHM=COPY+LOCK=SHARED方式，操作期间允许读不允许写。
ALTER TABLE TB001 CHANGE C1 C1 INT;
Query OK, 800000 rows affected (25.03 sec)
Records: 800000  Duplicates: 0  Warnings: 0

ALTER TABLE TB001 
CHANGE C1 C1 BIGINT,
ALGORITHM = INPLACE;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.

自增属性修改

1、修改普通主键列为自增主键列

## 只能使用ALGORITHM=COPY+LOCK=SHARED方式，操作期间允许读不允许写。
ALTER TABLE TB001 MODIFY ID BIGINT AUTO_INCREMENT;
Query OK, 800000 rows affected (26.15 sec)
Records: 800000  Duplicates: 0  Warnings: 0

2、修改自增主键列为普通主键列

## 只能使用ALGORITHM=COPY+LOCK=SHARED方式，操作期间允许读不允许写。
ALTER TABLE TB001 MODIFY ID BIGINT NOT NULL;
Query OK, 800000 rows affected (28.27 sec)
Records: 800000  Duplicates: 0  Warnings: 0

3、修改表自增开始值

## 仅需要修改元数据信息，操作时间极短。
ALTER TABLE TB001 AUTO_INCREMENT=800020;
Query OK, 0 rows affected (0.07 sec)
Records: 0  Duplicates: 0  Warnings: 0

列属性修改

1、新增列

## 可以使用ALGORITHM=INPLACE+LOCK=NONE方式，操作期间允许读写。
## 无论是新增可为NULL的列还是NOT NULL的列
ALTER TABLE TB001
ADD C2 INT NOT NULL DEFAULT 99999,
ALGORITHM=INPLACE, LOCK=NONE;

Query OK, 0 rows affected (33.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

2、删除列

## 可以使用ALGORITHM=INPLACE+LOCK=NONE方式，操作期间允许读写。
ALTER TABLE TB001
DROP COLUMN C5,
ALGORITHM=INPLACE, LOCK=NONE;
Query OK, 0 rows affected (33.57 sec)
Records: 0  Duplicates: 0  Warnings: 0

3、修改列数据类型(INT至BIGINT)

## 只能使用ALGORITHM=COPY+LOCK=SHARED方式，操作期间允许读不允许写。
ALTER TABLE TB001
CHANGE C5 C5 BIGINT NULL,
ALGORITHM=INPLACE, LOCK=NONE;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.

ALTER TABLE TB001
CHANGE C5 C5 BIGINT NULL,
ALGORITHM=COPY, LOCK=SHARED;

Query OK, 0 rows affected (29.63 sec)
Records: 0  Duplicates: 0  Warnings: 0

4、修改列类型显示长度(INT(10)至INT(8)或INT(8)至INT(10))

## 无论使用CHANGE命令还是MODIFY命令，都是修改元数据，操作时间极短。
ALTER TABLE tb001 
MODIFY C2 INT(8),
ALGORITHM=INPLACE, LOCK=NONE;
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0


ALTER TABLE tb001 
CHANGE C2 C2 INT(8) DEFAULT NULL,
ALGORITHM=INPLACE, LOCK=NONE;
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

5、修改列类型扩展存储长度(VARCHAR(300)至VARCHAR(500))

## 无论使用CHANGE命令还是MODIFY命令，都是修改元数据，操作时间极短。
ALTER TABLE tb001 
CHANGE C3 C3 varchar(500) DEFAULT NULL,
ALGORITHM=INPLACE, LOCK=NONE;
Query OK, 0 rows affected (0.14 sec)
Records: 0  Duplicates: 0  Warnings: 0

ALTER TABLE tb001 
MODIFY COLUMN C3 VARCHAR(500),
ALGORITHM=INPLACE, LOCK=NONE;
Query OK, 0 rows affected (0.14 sec)
Records: 0  Duplicates: 0  Warnings: 0

6、修改列类型扩展存储长度(VARCHAR(10)至VARCHAR(100))

## 只能使用ALGORITHM=COPY+LOCK=SHARED方式，操作期间允许读不允许写。
ALTER TABLE tb001
MODIFY COLUMN C3 VARCHAR(100), 
ALGORITHM=INPLACE, LOCK=NONE;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.


ALTER TABLE tb001
MODIFY COLUMN C3 VARCHAR(100), 
ALGORITHM=COPY, LOCK=SHARED;
Query OK, 0 rows affected (33.57 sec)
Records: 0  Duplicates: 0  Warnings: 0

7、修改列类型收缩存储长度(VARCHAR(500)至VARCHAR(300))

## 只能使用ALGORITHM=COPY+LOCK=SHARED方式，操作期间允许读不允许写。
ALTER TABLE tb001 
CHANGE C3 C3 VARCHAR(300) DEFAULT NULL,
ALGORITHM=INPLACE, LOCK=NONE;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.

ALTER TABLE tb001 
MODIFY COLUMN C3 VARCHAR(300),
ALGORITHM=INPLACE, LOCK=NONE;
ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.


ALTER TABLE tb001 
MODIFY COLUMN C3 VARCHAR(300),
ALGORITHM=COPY, LOCK=SHARED;
Query OK, 800009 rows affected (27.28 sec)
Records: 800009  Duplicates: 0  Warnings: 0

8、修改修改列注释

## 仅需修改元数据，操作时间极短
ALTER TABLE tb001 
MODIFY  COLUMN C3` varchar(300) DEFAULT NULL COMMENT '测试1';
Query OK, 0 rows affected (0.04 sec)
Records: 0  Duplicates: 0  Warnings: 0

ALTER TABLE tb001 
CHANGE C3 C3 varchar(300) DEFAULT NULL COMMENT '测试2';
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

MySQL 5.7版本下DDL操作