MariaDB 10.4.11 (GA) changes and improvements

1, account lockout

Allows administrators to lock / unlock the user account, the statement:

1 Lock

ALTER USER 'hechunyang'@'%' ACCOUNT LOCK;

When locked, when the user logs on again, the following message appears:

# mysql -h127.0.0.1 -uhechunyang -p -P3312

Enter password:

ERROR 4151 (HY000): Access denied, this account is locked

2 Unlock

ALTER USER 'hechunyang'@'%' ACCOUNT UNLOCK;

Note: The account is locked out , existing connections are not affected, the new client does not allow connections.

3 View account lockout information

> show create user hechunyang@'%'\G;

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

CREATE USER for hechunyang@%: CREATE USER 'hechunyang'@'%'

IDENTIFIED BY PASSWORD

'*1DA3AF2348DE66F7554E816DEDC1F1340814842E' ACCOUNT LOCK

> select * from mysql.global_priv where user='hechunyang'\G;

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

Host: %

User: hechunyang

Priv:

{"access":1073740799,"plugin":"mysql_native_password","authentication_string":"*

1DA3AF2348DE66F7554E816DEDC1F1340814842E","password_last_changed":15

76823835,"account_locked":true}

2, the user's password expires

1 Set expiration time user

>CREATE USER 'hechunyang'@'%' PASSWORD EXPIRE INTERVAL 1 DAY;

>ALTER USER 'hechunyang'@'%' PASSWORD EXPIRE INTERVAL 1 DAY;

Note: Only the default unit DAY (day), a minimum of 1 day.

When the user right expires prompted to change password at next logon, as follows:

[email protected][(none)]>show processlist;

ERROR 1820 (HY000): You must SET PASSWORD before executing this statement

2 解除限制

>ALTER USER 'hechunyang'@'%' PASSWORD EXPIRE NEVER;

3、支持更改字符集utf8->utf8mb4采用ALGORITHM=INSTANT算法

MariaDB支持表的某一字段，或者整张表，字符集utf8转换为utf8mb4采用ALGORITHM=INSTANT算法（只修改字典信息）

例表结构：

CREATE TABLE t1 (

id int(11) DEFAULT NULL,

cid int(11) DEFAULT NULL,

name varchar(60) DEFAULT NULL,

KEY IX_cid (cid)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DDL变更语句（秒级更改）

alter table t1 modify name varchar(60) charset utf8mb4, ALGORITHM=INSTANT;

需要注意的地方：

1）反过来utf8mb4->utf8是不支持INSTANT算法的。

2）如果你的字段是latin1拉丁文，转utf8/utf8mb4是不支持INSTANT算法的。

注：在MySQL 8.0.18版本中，修改字符集utf8->utf8mb4是无法使用到INSTANT算法的，需要重建表（ALGORITHM=COPY算法），且会锁表，update/delete/insert/replace into语句会被MDL锁住（Waiting for table metadata lock）

4、字段长度不大于varchar(256)，支持采用ALGORITHM=INSTANT算法

例表结构：

CREATE TABLE t1 (

id int(11) DEFAULT NULL,

cid int(11) DEFAULT NULL,

name varchar(60) DEFAULT NULL,

KEY IX_cid (cid)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DDL变更语句（秒级更改）

alter table t1 modify name varchar(80) DEFAULT NULL, ALGORITHM=INSTANT;

需要注意的地方：

1）varchar(60)减少到varchar(40)是不支持INSTANT算法的。

2）大于并等于varchar(256)，这里的256是指字节（UTF8占用3字节），是不支持INSTANT算法的。

注：只对varchar类型采用INSTANT算法，char和int是无效的，仍旧是需要拷贝数据且锁表。