shell_mysql.md/mysql-MD/第四章：数据库日志管理.md

<h1><center>数据库日志管理</center></h1>

**作者：行癫（盗版必究）**

------

## 一：日志管理

<img src="https://xingdian-image.oss-cn-beijing.aliyuncs.com/xingdian-image/image-20220925214046253.png" alt="image-20220925214046253" style="zoom:50%;" />

#### 1.日志分类

​		错误日志 ：启动，停止，关闭失败报错。rpm安装日志位置 /var/log/mysqld.log

​		通用查询日志：所有的查询都记下来

​		二进制日志：实现备份，增量备份。只记录改变数据，除了select都记

​		中继日志：读取主服务器的binlog，在本地回放。保持一致

​		slow log：慢查询日志，指导调优，定义某一个查询语句，定义超时时间，通过日志提供调优建议给开发人员

​		DDL log： 定义语句的日志

#### 2.Error Log

```shell
log-error=/var/log/mysqld.log
```

#### 3.Binary Log

```
log-bin=/var/log/mysql-bin/slave2
server-id=2

[root@slave2 ~]# mkdir /var/log/mysql-bin
[root@slave2 ~]# chown mysql.mysql /var/log/mysql-bin/
[root@slave2 ~]# systemctl restart mysqld
```

注意：

​		需要提前开启

查看binlog日志：

```shel
[root@slave2 ~]# mysqlbinlog slave2-bin.000001     -v --base64-output=decode-rows
        时间点  ：  141126 14:04:49
        位置点  :     at  106
注：
1. 重启mysqld 会截断
2. flush logs 会截断
3. reset master 删除所有binlog    rm -rf /var/lib/mysql/*.000001
4. 删除部分
PURGE BINARY LOGS TO 'mysql-bin.010';
PURGE BINARY LOGS BEFORE '2019-04-02 22:46:26';

截取binlog
all：
# mysqlbinlog mysql.000002

datetime：
# mysqlbinlog mysql.000002 --start-datetime="2018-12-05 10:02:56"
# mysqlbinlog mysql.000002 --stop-datetime="2018-12-05 11:02:54"
# mysqlbinlog mysql.000002 --start-datetime="2018-12-05 10:02:56" --stop-datetime="2018-12-05 11:02:54" 
 
position：
# mysqlbinlog mysql.000002 --start-position=260
# mysqlbinlog mysql.000002 --stop-position=260
# mysqlbinlog mysql.000002 --start-position=260 --stop-position=930
```

#### 4.Slow Query Log

开启慢查询日志：

```shell
[root@xingdian ~]# vim /etc/my.cnf
slow_query_log=1
slow_query_log_file=/var/log/mysql-slow/slow.log
long_query_time=3   设置慢查询超时时间  单位是：秒
```

创建对应目录：

```shell
[root@xingdian ~]# mkdir /var/log/mysql-slow
[root@xingdian ~]# chown mysql.mysql mysql-slow
```

重启服务：

```shell
[root@xingdian ~]# systemctl restart mysqld
```

验证：

```shell
[root@xingdian ~]# mysql -uroot -pQianFeng@123
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.39-log MySQL Community Server (GPL)

Copyright (c) 2000, 2022, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select sleep(6); 
+----------+
| sleep(6) |
+----------+
|        0 |
+----------+
1 row in set (6.00 sec)

mysql> exit
Bye
[root@xingdian ~]# cat /var/log/mysql-slow/slow.log 
/usr/sbin/mysqld, Version: 5.7.39-log (MySQL Community Server (GPL)). started with:
Tcp port: 0  Unix socket: /var/lib/mysql/mysql.sock
Time                 Id Command    Argument
# Time: 2022-09-25T06:58:05.496205Z
# User@Host: root[root] @ localhost []  Id:     2
# Query_time: 6.007094  Lock_time: 0.000000 Rows_sent: 1  Rows_examined: 0
SET timestamp=1664089085;
select sleep(6);
```