1, support for DROP COLUMN adopt remove fields ALGORITHM = INSTANT algorithm
例：alter table t1 drop column name,ALGORITHM=INSTANT;
MySQL 8.0.17 version does not support the algorithm
2, support change the character set utf8-> utf8mb4 conversion using ALGORITHM = INSTANT algorithm
例：alter table t1 change name name varchar(100) CHARSET utf8mb4,ALGORITHM=INSTANT;
MySQL 8.0.17 version does not support the algorithm
3, increase the authentication plug - Unix Socket
U nix_socket authentication plug-in allows users to local Unix socket file to connect to MariaDB when using the operating system's credentials .
usage:
1 , create a database account hechunyang
MariaDB [(none)]> GRANT ALL ON *.* TO 'hechunyang' IDENTIFIED VIA
unix_socket;
Query OK, 0 rows affected (0.001 sec)
2、创建操作系统账号hechunyang
# useradd hechunyang
# passwd hechunyang
以hechunyang用户登录操作系统
3、登录MariaDB
[root@localhost ~]# su - hechunyang
Last login: Wed Jul 31 14:18:17 CST 2019 on pts/2
[hechunyang@localhost ~]$
[hechunyang@localhost ~]$ mysql -S /tmp/mysql3306.sock -uhechunyang
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 45
Server version: 10.4.6-MariaDB-log MariaDB Server
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| test |
+--------------------+
2 rows in set (0.001 sec)
在此示例中，用户hechunyang已登录操作系统并具有完全shell访问权限。他已经使用操作系统进行了身份验证，并且他的MariaDB帐户已配置为使用unix_socket身份验证插件，因此他无需再次对数据库进行身份验证。MariaDB接受他的操作系统凭证并允许他连接。
4、mysqladmin shutdown命令增加--wait-for-all-slaves参数，意思为在关闭mysqld进程之前等待最后一个binlog事件发送到所有连接的Slave从库.
例：MariaDB [(none)]> SHUTDOWN WAIT FOR ALL SLAVES;
Query OK, 0 rows affected (0.000 sec)