MySQL的查詢日志記錄了所有MySQL數據庫請求的信息。無論這些請求是否得到了正確的執行。默認文件名為hostname.log。默認情況下MySQL查詢日志是關閉的。生產環境,如果開啟MySQL查詢日志,對性能還是有蠻大的影響的。另外很多時候,MySQL慢查詢日志基本可以定位那些出現性能問題的SQL,所以MySQL查詢日志應用的場景其實不多,有點雞肋的感覺,它跟SQL Server中的profiler有點類似,但是這個不能跟蹤某個會話、用戶、客戶端。它只能對整個數據庫進行跟蹤。
window 環境下
- 找到my.ini,在下面添加:
log=存放日志的路徑/my.log - 保存文件,重啟mysql服務,之后就可以在對應目錄的下找到my.log文件。
linux環境下
- MySQL中的參數general_log用來控制開啟、關閉MySQL查詢日志,參數general_log_file用來控制查詢日志的位置。所以如果你要判斷MySQL數據庫是否開啟了查詢日志,可以使用下面命令。general_log為ON表示開啟查詢日志,OFF表示關閉查詢日志。
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mysql> show variables like '%general_log%'; +------------------+------------------------------+ | Variable_name | Value | +------------------+------------------------------+ | general_log | OFF | | general_log_file | /var/lib/mysql/DB-Server.log | +------------------+------------------------------+ 2 rows in set (0.00 sec) mysql>
- 另外,MySQL的查詢日志支持寫入文件或寫入數據表兩種形式,這個由參數log_output控制,如下所示:
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mysql> show variables like 'log_output'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_output | FILE | +---------------+-------+ 1 row in set (0.00 sec) mysql>
- 1、開啟MySQL查詢日志
mysql> set global general_log = on; Query OK, 0 rows affected (0.11 sec) mysql> show variables like 'general_log'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | general_log | ON | +---------------+-------+ 1 row in set (0.02 sec) mysql>
- 2:關閉MySQL查詢日志
mysql> show variables like 'general_log'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | general_log | ON | +---------------+-------+ 1 row in set (0.01 sec) mysql> set global general_log=off; Query OK, 0 rows affected (0.01 sec) mysql> show variables like 'general_log'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | general_log | OFF | +---------------+-------+ 1 row in set (0.00 sec) mysql>
- 3:設置日志輸出方式為表(如果設置log_output=table的話,則日志結果會記錄到名為gengera_log的表中,這表的默認引擎是CSV):
mysql> show variables like 'log_output'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_output | FILE | +---------------+-------+ 1 row in set (0.00 sec) mysql> set global log_output='table'; Query OK, 0 rows affected (0.00 sec) mysql> show variables like 'log_output'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_output | TABLE | +---------------+-------+ 1 row in set (0.01 sec) mysql>
- 4.查看查詢日志信息。
mysql> select * from mysql.general_log; +---------------------+---------------------------+-----------+-----------+--------------+----------------------------------+ | event_time | user_host | thread_id | server_id | command_type | argument | +---------------------+---------------------------+-----------+-----------+--------------+----------------------------------+ | 2017-07-06 12:32:05 | root[root] @ localhost [] | 1 | 1 | Query | show variables like 'general%' | | 2017-07-06 12:32:28 | root[root] @ localhost [] | 1 | 1 | Query | show variables like 'log_output' | | 2017-07-06 12:32:41 | root[root] @ localhost [] | 1 | 1 | Query | select * from MyDB.test | | 2017-07-06 12:34:36 | [root] @ localhost [] | 3 | 1 | Connect | root@localhost on | | 2017-07-06 12:34:36 | root[root] @ localhost [] | 3 | 1 | Query | KILL QUERY 1 | | 2017-07-06 12:34:36 | root[root] @ localhost [] | 3 | 1 | Quit | | | 2017-07-06 12:34:51 | root[root] @ localhost [] | 1 | 1 | Query | select * from mysql.general_log | +---------------------+---------------------------+-----------+-----------+--------------+----------------------------------+ 7 rows in set (0.02 sec) mysql>