MySQL 日志管理

由于rizhi文件是掌握数据库运行的重要参考。因此日志文件的维护也是十分重要的意义

MySQL的日志类型：错误日志，普通查询日志，二进制日志，慢查询日志

1.错误日志

（1）错误日志主要记录当MySQL启动和停止时，以及在运行过程中发生任何错误时的相关消息。错误日志迷人保存在MySQL的安装路径data文件夹下，后缀名为.err。在配置文件中指定

[root@localhost data] vim /etc/my.cnf #在mysqld里面添加
[mysqld]
log-error=/usr/local/mysql/data/mysql_error.log
[root@localhost ~]# systemctl restart mysqld.service #重启之后会生成这个文件
[root@localhost ~]# cd /usr/local/mysql/data/
[root@localhost data]# ls
mysql_error.log

2：查询通用日志

（1）通用查询日志用来记录MySQL的所有连接的语句，默认状态关闭，。使用SHOW可以查询处日志信息

mysql> show variables like 'general%';
+------------------+-------------------------------------+
| Variable_name    | Value                               |
+------------------+-------------------------------------+
| general_log      | OFF                                 |
| general_log_file | /usr/local/mysql/data/localhost.log |
+------------------+-------------------------------------+
2 rows in set (0.01 sec)

在配置文件中声明开启

[root@localhost data] vim /etc/my.cnf
[mysqld]
general_log=ON
general_log_file=/usr/local/mysql/data/mysql_general.log
[root@localhost data] systemctl restart mysqld.service
mysql_general.log
mysql> show variables like 'general%'; #状态开启
+------------------+-----------------------------------------+
| Variable_name    | Value                                   |
+------------------+-----------------------------------------+
| general_log      | ON                                      |
| general_log_file | /usr/local/mysql/data/mysql_general.log |
+------------------+-----------------------------------------+
2 rows in set (0.01 sec)

3：二进制日志

二进制日志用来记录所有更新或者已经潜在更新了数据的语句，记录了数据的更改主要目的是能够最大程度的恢复数据

mysql> show variables like 'log_bin%'; #默认是关闭状态
+---------------------------------+-------+
| Variable_name                   | Value |
+---------------------------------+-------+
| log_bin                         | OFF   |
| log_bin_basename                |       |
| log_bin_index                   |       |
| log_bin_trust_function_creators | OFF   |
| log_bin_use_v1_row_events       | OFF   |
+---------------------------------+-------+
5 rows in set (0.00 sec)

在配置文件中加入一句话

[root@localhost data] vim /etc/my.cnf
[mysqld]
log_bin=mysql-bin
[root@localhost data] systemctl restart mysqld.service
[root@localhost data] ls
mysql-bin.000001
mysql-bin.index
[root@localhost data]# mysql -u root -p
mysql> show variables like 'log_bin%';
+---------------------------------+---------------------------------------+
| Variable_name                   | Value                                 |
+---------------------------------+---------------------------------------+
| log_bin                         | ON                                    |
| log_bin_basename                | /usr/local/mysql/data/mysql-bin       |
| log_bin_index                   | /usr/local/mysql/data/mysql-bin.index |
| log_bin_trust_function_creators | OFF                                   |
| log_bin_use_v1_row_events       | OFF                                   |
+---------------------------------+---------------------------------------+
5 rows in set (0.01 sec)

查询二进制命令

[root@localhost data] mysqlbinlog --no-defaults mysql-bin.000001  #关闭默认的utf8字符集
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
DELIMITER /*!*/;
# at 4
#180628 16:56:21 server id 1  end_log_pos 123 CRC32 0x4ecddb44  Start: binlog v 4, server v 5.7.17-log created 180628 16:56:21 at startup
# Warning: this binlog is either in use or was not closed properly.
ROLLBACK/*!*/;
BINLOG '
taI0Ww8BAAAAdwAAAHsAAAABAAQANS43LjE3LWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAC1ojRbEzgNAAgAEgAEBAQEEgAAXwAEGggAAAAICAgCAAAACgoKKioAEjQA
AUTbzU4=
'/*!*/;
# at 123
#180628 16:56:21 server id 1  end_log_pos 154 CRC32 0x0b6126ac  Previous-GTIDs
# [empty]
SET @@SESSION.GTID_NEXT= 'AUTOMATIC' /* added by mysqlbinlog */ /*!*/;
DELIMITER ;
# End of log file
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;

4:慢查询日志

慢查询日志是记录所有命令执行时间查过long_query_time的设置时间用于查询那些超过系统设置的时间与其对其进行优化

mysql> show variables like '%slow%'; #默认是关闭的
+---------------------------+------------------------------------------+
| Variable_name             | Value                                    |
+---------------------------+------------------------------------------+
| log_slow_admin_statements | OFF                                      |
| log_slow_slave_statements | OFF                                      |
| slow_launch_time          | 2                                        |
| slow_query_log            | OFF                                      |
| slow_query_log_file       | /usr/local/mysql/data/localhost-slow.log |
+---------------------------+------------------------------------------+
5 rows in set (0.00 sec)

对其进行开启

第一种方法

mysql> set global slow_query_log=ON;
Query OK, 0 rows affected (0.01 sec)mysql> show variables like '%slow%';
+---------------------------+------------------------------------------+
| Variable_name             | Value                                    |
+---------------------------+------------------------------------------+
| log_slow_admin_statements | OFF                                      |
| log_slow_slave_statements | OFF                                      |
| slow_launch_time          | 2                                        |
| slow_query_log            | ON     #开启                                  |
| slow_query_log_file       | /usr/local/mysql/data/localhost-slow.log |
+---------------------------+------------------------------------------+
5 rows in set (0.00 sec)

第二种方法直接在配置文件里面设定

[root@localhost data] vim /etc/my.cnf
slow_query_log=ON           #开启慢日志
slow_query_log_file=mysql_slow_query.log
long_query_time=5 #时间为5秒

查看慢查询时间

mysql> show variables like 'long_query_time';
+-----------------+----------+
| Variable_name   | Value    |
+-----------------+----------+
| long_query_time | 5.000000 |
+-----------------+----------+
1 row in set (0.00 sec)

MySQL里面的乱码是设定它的字符集两种方法

1：临时修改

mysql> set names utf8; #开启重启后失效

2：永久性修改(安装MySQL的时候在配置文件里面就指定字符集utf-8格式)

[root@localhost data] vim /etc/my.cnf
[client]
default-character-set=utf8
[mysql]
default-char[mysqld]
[mysqld]
character_set_server=utf8