分类目录归档：MySQL

MySQL二进制日志清理

  1. 查看过期天数

show variables like ‘%logs%’;

2. 设置过期天数（最大值为99）

set global expire_logs_days = 99;

MySQL8.0 支持binlog_expire_logs_seconds参数，顾名思义就是日志过期秒数。

自动二进制日志文件删除的天数。 默认值为0，表示“不自动删除”。 可能的删除发生在启动时和二进制日志刷新。

2.1 生效问题

flush logs;

如果你发现设置没有生效，可能需要执行此命令。

3. 查看现有的日志文件

SHOW BINARY LOGS;

4. 手动清理较旧日志

PURGE BINARY LOGS TO ‘mysql-bin.000007’;

将mysql-bin.000007以前的日志清理掉，又或者

PURGE BINARY LOGS BEFORE ‘2018-01-06 12:12:12’;

将2018-01-06 12:12:12以前的日志清理掉

5. 修改MySQL配置文件

expire_logs_days = 99

 

create table和主从复制一坑

正确：
CREATE TABLE `chapter_lock_reason` (
`id` INT(11) NOT NULL AUTO_INCREMENT
PRIMARY KEY (`id`)
);

错误的方式：
CREATE TABLE xxx.`chapter_lock_reason` (
`id` INT(11) NOT NULL AUTO_INCREMENT
PRIMARY KEY (`id`)
);

MySQL ARCHIVE 引擎，从库突然Can’t write; duplicate key in table ‘nopay_record” on query.

这是ARCHIVE引擎的BUG

Error ‘Can’t write; duplicate key in table ‘nopay_record” on query. Default database: ‘doufu’. Query: ‘insert into `nopay_record` (`user_id`, `novel_id`, `chapter_id`, `channel`, `created_at`) values (3927416, 365027, 2499984, NULL, ‘2017-12-29 23:38:01′)’

表结构:

CREATE TABLE `nopay_record` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11) NOT NULL,
`novel_id` int(11) NOT NULL,
`chapter_id` int(11) NOT NULL,
`channel` tinyint(4) DEFAULT NULL,
`created_at` timestamp NOT NULL DEFAULT ‘0000-00-00 00:00:00’,
`updated_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=ARCHIVE AUTO_INCREMENT=440357 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

改成innodb吧

又一个MySQL坑 

SELECT * FROM novel where title='一间客栈（连载）' ;
SELECT * FROM novel where title='一间客栈（连载） ' ;

SELECT * FROM novel where title=binary(‘一间客栈（连载）’ );
不加binary，MySQL会忽略大小写和首尾空格;

xtrabackup 快速增量备份教程

xtrabackup –backup –compress –target-dir=/mysqlbackup/full –user=aaa –host=hostname –password=xxxx –databases=ggggg

xtrabackup –backup –compress –target-dir=/mysqlbackup/incr –incremental-basedir=/mysqlbackup/full –user=aaa –host=hostname –password=xxxx –databases=ggggg

 

–compress 压缩

MySQL UPDATE JOIN

JOIN似乎不太满足这里的需求子查询更好

UPDATE novel 
SET 
    chat_num = (SELECT 
            COUNT(*)
        FROM
            chats
        WHERE
            novel_id = ? AND status = 1)
WHERE
    id = ?

UPDATE JOIN 似乎无法使用limit

UPDATE pay_record
        JOIN
    article_info ON article_info.id = pay_record.object_id 
SET 
    novel_id = special_id
WHERE
    ISNULL(novel_id) AND pay_record.id = 17;

MySQL类型不匹配导致的慢查询

这是个慢查询

SELECT *, `user_id` as uid
FROM (`journals`)
WHERE `user_id` IN ('1456870', 2573141) -- 字符串
AND `status` =  1
ORDER BY `id` desc
LIMIT 20

这个则不是

SELECT *, `user_id` as uid
FROM (`journals`)
WHERE `user_id` IN (1456870, 2573141) -- 数字
AND `status` =  1
ORDER BY `id` desc
LIMIT 20