MySQL日誌文件

時間 2019-12-12

標籤 mysql 日誌文件欄目 MySQL 简体版

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MySQL日誌文件

日誌文件記錄了影響MySQL數據庫的各類類型活動，MySQL數據庫中常見的日誌文件有錯誤日誌、二進制日誌、慢查詢日誌。
這些日誌文件爲DBA對數據庫優化、問題查找帶來了極大的便利。mysql

日誌的輸出格式

參數log_output指定了慢查詢輸出的格式，默認爲FILE,你能夠設置爲TABLE,而後就能夠在mysql架構下查詢相關的表了。sql

"日誌輸出方式"
mysql> show variables like 'log_output%';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_output    | FILE  |
+---------------+-------+
1 row in set (0.00 sec)

"更改成TABLE"
mysql> set global log_output='TABLE';
Query OK, 0 rows affected (0.00 sec)

"輸出內容"
mysql> select event_time,user_host,argument  from general_log;
+---------------------+---------------------------+--------------------------------------------------------+
| event_time          | user_host                 | argument                                               |
+---------------------+---------------------------+--------------------------------------------------------+
| 2016-09-30 14:36:36 | root[root] @ localhost [] | show variables like 'log_output%'                      |
| 2016-09-30 14:37:17 | root[root] @ localhost [] | show tables                                            |
| 2016-09-30 14:37:29 | root[root] @ localhost [] | select * from general_log                              |
| 2016-09-30 14:37:36 | root[root] @ localhost [] | select * from general_log                              |
| 2016-09-30 14:38:03 | root[root] @ localhost [] | select * from general_log                              |
| 2016-09-30 14:38:30 | root[root] @ localhost [] | select event_time,user_host,argument  from general_log |
+---------------------+---------------------------+--------------------------------------------------------+

MySQL啓動/中止/重啓方式

1、啓動數據庫

使用 service 啓動：service mysqld start架構

使用 mysqld 腳本啓動：/etc/inint.d/mysqld startsocket

使用 mysqld_safe 啓動：mysqld_safe&優化

2、中止rest

使用 service 啓動：service mysqld stop日誌

使用 mysqld 腳本啓動：/etc/inint.d/mysqld stopcode

mysqladmin shutdown索引

3、重啓

使用 service 啓動：service mysqld restart

使用 mysqld 腳本啓動：/etc/inint.d/mysqld restart

1.錯誤日誌

錯誤日誌文件對MySQL的啓動、運行、關閉過程進行了記錄。MySQL DBA在遇到問題時應該首先查看該文件。該文件不但記錄了出錯信息，也記錄一些警告信息或者正確的信息。

"經過 show variables like log_error來定位該文件"

mysql> show variables like 'log_error';
+---------------+------------------------+
| Variable_name | Value                  |
+---------------+------------------------+
| log_error     | /var/log/mysql/err.log |
+---------------+------------------------+
1 row in set (0.00 sec)

"文件內容"

160930 14:00:57 [Note] Event Scheduler: Killing the scheduler thread, thread id 1
160930 14:00:57 [Note] Event Scheduler: Waiting for the scheduler thread to reply
160930 14:00:57 [Note] Event Scheduler: Stopped
160930 14:00:57 [Note] Event Scheduler: Purging the queue. 9 events
160930 14:00:57  InnoDB: Starting shutdown...
160930 14:00:58  InnoDB: Shutdown completed; log sequence number 892930378
160930 14:00:58 [Note] /usr/local/mysql/bin/mysqld: Shutdown complete

2.慢查詢日誌

設置一個閾值，將運行時間超過該值的全部SQL語句都記錄到慢查詢日誌文件中。
默認狀況下，MySQL數據庫並不啓動慢查詢日誌，你須要手工將這個參數設爲ON

"記錄慢查詢的時間閾值"
mysql> show variables like '%long%'
    -> ;
+---------------------------------------------------+----------+
| Variable_name                                     | Value    |
+---------------------------------------------------+----------+
| long_query_time                                   | 0.001000 |
+---------------------------------------------------+----------+
3 rows in set (0.05 sec)


2."查詢慢查詢日誌是否開啓"
mysql> show variables like 'log_slow_queries';
+------------------+-------+
| Variable_name    | Value |
+------------------+-------+
| log_slow_queries | OFF   |
+------------------+-------+
1 row in set (0.02 sec)

3."若是運行的SQL沒有索引，慢查詢日誌是否記錄"
mysql> show variables like 'log_queries_not_using_indexes';
+-------------------------------+-------+
| Variable_name                 | Value |
+-------------------------------+-------+
| log_queries_not_using_indexes | OFF   |
+-------------------------------+-------+
1 row in set (0.00 sec)

4."更改設置"
mysql> set global log_slow_queries='ON'
    -> ;
Query OK, 0 rows affected, 1 warning (0.05 sec)

3.查詢日誌

查詢日誌記錄了全部對MySQL數據庫請求的信息，不論這些請求是否獲得了正確的執行。

"打開查詢日誌"
mysql> set global general_log='on';
Query OK, 0 rows affected (0.00 sec)

"日誌所在位置"
mysql> show variables like 'general%';
+------------------+-------------------------------------+
| Variable_name    | Value                               |
+------------------+-------------------------------------+
| general_log      | ON                                  |
| general_log_file | /usr/local/mysql/data/localhost.log |
+------------------+-------------------------------------+

"文件內容"
mysql> system more /usr/local/mysql/data/localhost.log ;

Tcp port: 3306  Unix socket: /tmp/mysql.sock
Time                 Id Command    Argument
160930 14:25:15     3 Query     show variables like 'general%'
160930 14:25:31     3 Query     select * from general_log
160930 14:25:33     3 Query     select * from general_log
160930 14:25:34     3 Query     select * from general_log
160930 14:25:35     3 Query     select * from general_log
160930 14:25:36     3 Query     select * from general_log