引言：MariaDB在MySQL被Oracle收归旗下之后，开始作为Linux默认的数据库系统，这里主要描述在Ubuntu 16.04下如何来安装MariaDB的步骤。
1. 安装指令
sudo apt install software-properties-common
sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xF1656F24C74CD1D8
执行结果：
Executing: /tmp/tmp.p9r0OfEIH2/gpg.1.sh --recv-keys
--keyserver
hkp://keyserver.ubuntu.com:80
0xF1656F24C74CD1D8
gpg: requesting key C74CD1D8 from hkp server keyserver.ubuntu.com
gpg: key C74CD1D8: public key "MariaDB Signing Key <signing-key@mariadb.org>" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
sudo add-apt-repository 'deb [arch=amd64,i386,ppc64el] xenial main'
这里选中清华的数据服务
sudo apt update
执行结果如下：
linuxidc@linuxidc:~$ sudo apt update
Hit:1 xenial InRelease
Hit:2 xenial-updates InRelease
Get:3 xenial-backports InRelease [92.2 kB]
Get:4 xenial-security InRelease [94.5 kB]
Hit:5 xenial InRelease
Get:6 xenial InRelease [3,874 B]
Get:7 xenial/main amd64 Packages [5,865 B]
Get:8 xenial/main i386 Packages [5,864 B]
Fetched 202 kB in 7s (26.7 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
3 packages can be upgraded. Run 'apt list --upgradable' to see them.
>> sudo apt install mariadb-server
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
linux-headers-4.4.0-28 linux-headers-4.4.0-28-generic linux-image-4.4.0-28-generic linux-image-extra-4.4.0-28-generic
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
galera-3 gawk iproute libjemalloc1 libmariadbclient18 libmysqlclient18 mariadb-client-10.2 mariadb-client-core-10.2 mariadb-common
mariadb-server-10.2 mariadb-server-core-10.2 socat
Suggested packages:
gawk-doc mailx mariadb-test tinyca
The following packages will be REMOVED:
mariadb-client-10.0 mariadb-client-core-10.0 mariadb-server-10.0 mariadb-server-core-10.0
The following NEW packages will be installed:
galera-3 gawk iproute libjemalloc1 libmariadbclient18 libmysqlclient18 mariadb-client-10.2 mariadb-client-core-10.2 mariadb-server-10.2
mariadb-server-core-10.2 socat
The following packages will be upgraded:
mariadb-common mariadb-server
2 upgraded, 11 newly installed, 4 to remove and 1 not upgraded.
Need to get 21.8 MB of archives.
After this operation, 48.4 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 xenial/main amd64 galera-3 amd64 25.3.15-xenial [7,741 kB]
Get:2 xenial/main amd64 gawk amd64 1:4.1.3+dfsg-0.1 [398 kB]
Get:3 xenial/main amd64 iproute all 1:4.3.0-1ubuntu3 [2,428 B]
Get:4 xenial/universe amd64 libjemalloc1 amd64 3.6.0-9ubuntu1 [78.9 kB]
Get:5 xenial/universe amd64 socat amd64 1.7.3.1-1 [321 kB]
Get:6 xenial/main amd64 mariadb-server all 10.2.1+maria-1~xenial [2,960 B]
Get:7 xenial/main amd64 libmysqlclient18 amd64 10.2.1+maria-1~xenial [2,932 B]
Get:8 xenial/main amd64 mariadb-common all 10.2.1+maria-1~xenial [3,234 B]
Get:9 xenial/main amd64 libmariadbclient18 amd64 10.2.1+maria-1~xenial [583 kB]
Get:10 xenial/main amd64 mariadb-client-core-10.2 amd64 10.2.1+maria-1~xenial [689 kB]
Get:11 xenial/main amd64 mariadb-client-10.2 amd64 10.2.1+maria-1~xenial [1,095 kB]
Get:12 xenial/main amd64 mariadb-server-core-10.2 amd64 10.2.1+maria-1~xenial [4,456 kB]
2. 查看sourcelist.
>> sudo vi /etc/apt/sources.list
# MariaDB 10.2 repository list - created 2016-08-14 12:39 UTC
#
deb [arch=amd64,i386] xenial main
deb-src xenial main
３. 无法连接Mariadb的问题
安装完成Mariadb之后，基于mysql workbench无法连接mariadb, 提示"Plugin 'unix_socket' is not loaded"的错误细心：
什么是unix_socket plugin?
是一种安全机制，允许使用操作系统的安全机制连接数据库，通过unix_socket组件，通常使用用在Ubuntu 15.04+以上的系统中。
解决的方法：
1. 尝试登陆mysql的命令, mysql -u root -p, 如果看到如下错误，则需要进入步骤２，否则直接进入步骤６．
linuxidc@linuxidc:~$ sudo mysql -u root -p
Enter password:
ERROR 1524 (HY000): Plugin 'unix_socket' is not loaded
这个原因是由于当前使用的unix_socket来进行连接，但是缺省的用户也无法进行访问。
2. 停止服务，使用设置native方式来访问，重置缺省密码
>> sudo systemctl stop mariadb # 停止服务
>> sudo mysqld_safe --skip-grant-tables & # 进入安全模式，并设置为后台进程
>> mysql -u root # 登陆mysql
>> select Host,User,plugin from mysql.user where User='root'; # 查询用户
>> update mysql.user set plugin='mysql_native_password'; #重置加密模式
>> update mysql.user set password=PASSWORD("newpassword") where User='root'; #重置密码
>> flush privileges; #刷新权限信息
>> exit
杀掉进程，重新启动服务
>> sudo kill -9 $(pgrep mysql) # 杀掉进程
>> sudo service mariadb start # 重新启动服务
３. 登陆mysql, 安装unix_soket
>> mysql -u root -p
>> install plugin unix_socket soname 'auth_socket';
然后就可以正常访问了。
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