MySQL 普通查詢日誌和慢查詢日誌介紹

1. 普通查詢日誌(general query log)介紹

普通查詢日誌記錄客戶端連接信息和執行的sql語句信息

mysql> show variables like 'general_log%';

+------------------+---------------------------+

| Variable_name    | Value                     |

+------------------+---------------------------+

| general_log      | OFF                       |            -> 默認爲關閉狀態

| general_log_file | /data/3306/data/node1.log |

+------------------+---------------------------+

mysql> set global general_log = ON;

mysql> set global general_log_file = "/data/3306/data/general_90root.log";

mysql> show variables like 'general_log%';

+------------------+------------------------------------+

| Variable_name    | Value                              |

+------------------+------------------------------------+

| general_log      | ON                                 |

| general_log_file | /data/3306/data/general_90root.log |

+------------------+------------------------------------+

## 以上配置臨時生效

[root@node1 ~]# cat /data/3306/my.cnf

[mysqld]

character_set_server = utf8

general_log = ON

general_log_file = "/data/3306/data/general_90root.log";  

[root@node1 ~]# /data/3306/mysql restart

[root@node1 ~]#  mysql -uroot -p90root3306 -S /data/3306/mysql.sock

mysql> show variables like 'general_log%';

+------------------+-------------------------------------+

| Variable_name    | Value                               |

+------------------+-------------------------------------+

| general_log      | ON                                  |

| general_log_file | /data/3306/data/general_90root.log  |

+------------------+-------------------------------------+

[root@node1 ~]# tail -f /data/3306/data/general_90root.log

160723  4:54:49     4 Query     show databases

mysql> show databases;

+--------------------+

| Database           |

+--------------------+

| information_schema |

| 90_root            |

| 90root             |

| 90root_gbk         |

| 90root_test        |

| ab                 |

| mysql              |

| performance_schema |

| test               |

| test_sz            |

+--------------------+

企業裏一般是關閉的, 因爲性能的問題

慢查詢日誌只記錄執行時間超出指定值的sql語句

慢查詢的設置對於數據庫sql的優化非常重要

[root@node1 ~]# cat /data/3306/my.cnf

[mysqld]

long_query_time     = 1                 -> sql執行語句超過1秒記錄到慢查詢日誌

slow-query-log-file   = /data/3306/slow.log     -> 慢查詢日誌文件路徑

log_queries_not_using_indexes           -> 沒有走索引的sql語句記錄到慢查詢日誌

[root@node1 ~]# /data/3306/mysql restart