攻城狮PHP,JAVA,LNAMPMenuSkip to content首页技术关于Linux 添加新硬盘Posted on 2016 年 12 月 01 日 by admin#查看在线的磁盘列表fdisk -l#编辑新添加的硬盘分区fdisk /dev/sdb#输入 m 列出命令列表（根据提示添加分区）#查看所有磁盘分区（列表中应该有类似 sdb1 ... 的新分区）ll /dev/sd*#格式化分区（分区类型根据不同需要选择）mkfs.xfs /dev/sdb1#挂载分区mkdir /datamount /dev/sdb1 /data/#编辑 /etc/fstab 文件，末尾添加下行，实现开机自动挂载分区/dev/sdb1 /data        xfs        defaults        0 0Posted in 服务器运维Leave a commentMySQL JSON数据类型 使用虚拟列创建索引Posted on 2016 年 11 月 07 日 by admin创建表及索引：CREATE TABLE `cartoon_data` (`id` bigint(20) UNSIGNED NOT NULL,`category` char(4) GENERATED ALWAYS AS (json_extract(`xml2json`,'$.category')) VIRTUAL,`xml2json` json NOT NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;ALTER TABLE `cartoon_data`ADD UNIQUE KEY `id` (`id`),ADD KEY `category` (`category`);查询 JSON 格式字段 不使用索引 与 使用虚拟列索引 对比：mysql> SELECT COUNT(*) FROM `cartoon_data` WHERE xml2json->'$.category' = 'cj';+----------+| COUNT(*) |+----------+|  1000000 |+----------+1 row in set (1.63 sec)mysql> EXPLAIN SELECT COUNT(*) FROM `cartoon_data` WHERE xml2json->'$.category' = 'cj';+----+-------------+--------------+------------+------+---------------+------+---------+------+--------+----------+-------------+| id | select_type | table        | partitions | type | possible_keys | key  | key_len | ref  | rows   | filtered | Extra       |+----+-------------+--------------+------------+------+---------------+------+---------+------+--------+----------+-------------+|  1 | SIMPLE      | cartoon_data | NULL       | ALL  | NULL          | NULL | NULL    | NULL | 953622 |   100.00 | Using where |+----+-------------+--------------+------------+------+---------------+------+---------+------+--------+----------+-------------+1 row in set, 1 warning (0.00 sec)mysql> SELECT COUNT(*) FROM `cartoon_data` WHERE category = '"cj"';+----------+| COUNT(*) |+----------+|  1000000 |+----------+1 row in set (0.31 sec)mysql> EXPLAIN SELECT COUNT(*) FROM `cartoon_data` WHERE category = '"cj"';+----+-------------+--------------+------------+------+---------------+----------+---------+-------+--------+----------+-------------+| id | select_type | table        | partitions | type | possible_keys | key      | key_len | ref   | rows   | filtered | Extra       |+----+-------------+--------------+------------+------+---------------+----------+---------+-------+--------+----------+-------------+|  1 | SIMPLE      | cartoon_data | NULL       | ref  | category      | category | 17      | const | 476811 |   100.00 | Using index |+----+-------------+--------------+------------+------+---------------+----------+---------+-------+--------+----------+-------------+1 row in set, 1 warning (0.00 sec)Posted in 数据库Leave a commentMySQL-5.7 双主互备+keepalivedPosted on 2016 年 09 月 12 日2016 年 09 月 12 日 by adminVIP : 192.168.56.100Server 1 : 192.168.56.101Server 2 : 192.168.56.102Step 1 : 安装 MySQL(192.168.56.101)//需删除 linux 系统自带的数据库配置文件/etc/my.cnf，否则安装过程中会默认加载此配置文件groupadd mysqluseradd -r -g mysql -s /bin/false mysqlchown -R mysql:mysql .bi