第 15、16章 MySQL日志和性能优化

日志分类：
错误日志
查询日志
二进制日志
慢查询日志

二进制日志

启动和设置二进制日志
首先找到mysql目录下的my.ini，打开它，找到[mysqld]组，添加以下几个参数：

添加完毕后，重启MySQL服务器，便可查询日志设置：

mysql> SHOW VARIABLES LIKE 'log_%';
+----------------------------------------+---------------------------------------+
| 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                                   |
| log_builtin_as_identified_by_password  | OFF                                   |
| log_error                              | E:\wamp64\bin\mysql\mysql5.7.14\data\ |
| log_error_verbosity                    | 3                                     |
| log_output                             | FILE                                  |
| log_queries_not_using_indexes          | OFF                                   |
| log_slave_updates                      | OFF                                   |
| log_slow_admin_statements              | OFF                                   |
| log_slow_slave_statements              | OFF                                   |
| log_statements_unsafe_for_binlog       | ON                                    |
| log_syslog                             | ON                                    |
| log_syslog_tag                         |                                       |
| log_throttle_queries_not_using_indexes | 0                                     |
| log_timestamps                         | UTC                                   |
| log_warnings                           | 2                                     |
+----------------------------------------+---------------------------------------+
19 rows in set, 6 warnings (0.05 sec)

如果想修改日志文件的目录和名称，可以对my.ini中的log_bin参数修改如下：

[mysqld]
log_bin=“E:/MYSQL/log/binlog”

关闭和重新启动后，新的二进制日志文件将出现在E:/MYSQL/log/binlog文件夹下面，名称为binlog.000001和binlog.index。

查看二进制文件

mysql> SHOW BINARY LOGS;
ERROR 1381 (HY000): You are not using binary logging

使用mysqlbinlog查看：

C:\Users\lenovo>mysqlbinlog D:\MySQL\log\binlog.000001
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
DELIMITER /*!*/;
mysqlbinlog: File 'D:\MySQL\log\binlog.000001' not found (Errcode: 2 - No such file or directory)
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*/;

删除二进制日志
a. RESET MASTER;
b. PURGE MASTER LOGS
使用二进制日志还原数据库
mybinlog恢复数据语法如下:

mysqlbinlog [option] filename |mysql -uuser -p pass

暂时停止二进制日志功能
SET SQL_LOG_BIN语法如下：

SET sql_log_bin={0|1}

0代表暂停，1代表恢复记录。

16章性能优化

使用索引查询：

使用LIKE关键字

mysql> USE index_test;
Database changed
mysql> EXPLAIN SELECT * FROM fruits WHERE f_name LIKE '_%x';
+----+-------------+--------+------------+------+---------------+------+---------+------+------+----------+-------------+
| id | select_type | table  | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+--------+------------+------+---------------+------+---------+------+------+----------+-------------+
|  1 | SIMPLE      | fruits | NULL       | ALL  | NULL          | NULL | NULL    | NULL |   16 |    11.11 | Using where |
+----+-------------+--------+------------+------+---------------+------+---------+------+------+----------+-------------+
1 row in set, 1 warning (0.15 sec)

mysql> EXPLAIN SELECT * FROM fruits WHERE f_name LIKE 'x%';
+----+-------------+--------+------------+------+---------------+------+---------+------+------+----------+-------------+
| id | select_type | table  | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+--------+------------+------+---------------+------+---------+------+------+----------+-------------+
|  1 | SIMPLE      | fruits | NULL       | ALL  | NULL          | NULL | NULL    | NULL |   16 |    11.11 | Using where |
+----+-------------+--------+------------+------+---------------+------+---------+------+------+----------+-------------+
1 row in set, 1 warning (0.00 sec)

使用多列索引

mysql> CREATE INDEX index_id_price ON fruits(f_id,f_price);
Query OK, 0 rows affected (0.89 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> EXPLAIN SELECT * FROM fruits WHERE f_id=5.2;
+----+-------------+--------+------------+------+------------------------+------+---------+------+------+----------+-------------+
| id | select_type | table  | partitions | type | possible_keys          | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+--------+------------+------+------------------------+------+---------+------+------+----------+-------------+
|  1 | SIMPLE      | fruits | NULL       | ALL  | PRIMARY,index_id_price | NULL | NULL    | NULL |   16 |    10.00 | Using where |
+----+-------------+--------+------------+------+------------------------+------+---------+------+------+----------+-------------+
1 row in set, 5 warnings (0.08 sec)

从第一条查询语句可以看出，f_id='12’的记录有一条。

使用OR关键字

mysql> EXPLAIN SELECT * FROM fruits WHERE f_name='apple' OR s_id=101\G;
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: fruits
   partitions: NULL
         type: ALL
possible_keys: NULL
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 16
     filtered: 19.00
        Extra: Using where
1 row in set, 1 warning (0.00 sec)

ERROR:
No query specified

优化插入记录速度：

禁用索引
禁用索引语句如下：

ALTER TABLE 	table_name DISABLE KEYS;

重新开启索引的语句如下：

ALTER TABLE table_name ENABLE KEYS;

禁用唯一性查询
禁用语句：

SET UNIQUE_CHECKS=0;

开启语句：

SET UNIQUE_CHECKS=1;

第 15、16章 MySQL日志和性能优化

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