MySQL log query log

28.1　 Query log

MySQL The query log in is saved in a text file , Be able to record MySQL All data operations in . This section briefly introduces how to open 、 View and delete MySQL Query log in .

28.1.1　 Open query log

MySQL Query logs are not enabled by default , If you need to open the query log , You need to in my.cnf Documents or my.ini Of documents [mysqld] Select to configure . for example , Configuration on MySQL Query log ：

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[mysqld]general_log = 1general_log_file = /data/mysql/log/general_log/general_statement.loglog_output = FILE

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Various configurations are described below ：

·general_log： Indicates whether the query log is enabled . This is set to 1 Or without any value , You can open the query log ; Set to 0 Or in my.cnf File or my.ini This item is not configured in the file , The query log will not be opened .

·general_log_file： Query the file directory of the log , The full path of the log is configured here .

·log_output： Indicates how logs are stored , There can be 3 Species value ,TABLE Indicates that the query log is stored in the data table ;FILE Means to save the query log to a file ;NONE It means that the log information is not saved to the data table and file .

Be careful ： When opening the query log , If not specified general_log_file Options and log_output The value of the option , be MySQL The query log will be saved to DATADIR Under the directory specified by the option （ That is, the data directory in the database ）, The default file name is host_name.log, among ,host_name by MySQL The host name .

Configure before starting the query log , First of all to see /data/mysql/log/general_log File information in directory .

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[[email protected] ~]# [[email protected] ~]# ll /data/mysql/log/general_log/total 0

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When not configured MySQL When querying logs for ,/data/mysql/log/general_log/ There are no files in the directory .

After the query log configuration is completed , Need to restart MySQL Service to take effect .

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[[email protected] ~]# service mysqld restartShutting down MySQL..... SUCCESS! Starting MySQL........ SUCCESS!

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It can also be in MySQL Specify on the command line MySQL Query log .

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mysql> SET GLOBAL general_log = 1;Query OK, 0 rows affected (0.01 sec)mysql> SET GLOBAL general_log_file = '/data/mysql/log/general_log/general_statement.log'; Query OK, 0 rows affected (0.00 sec)mysql> SET GLOBAL log_output = 'file';Query OK, 0 rows affected (0.00 sec)

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here , Look again /data/mysql/log/general_log/ A file in a directory .

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[[email protected] ~]# ll /data/mysql/log/general_log/total 4-rw-r----- 1 mysql mysql 547 Jan 17 11:39 general_statement.log

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When the query log configuration is completed ,MySQL Automatically created general_log_file Option to specify the log file .

28.1.2　 View query log

If log_output The option is configured to save the query log to a file , Then the format of the log file is plain text , You can directly view the contents of the log file .

for example , towards goods Database based t_goods_category Insert a piece of data into the data table , Then the query t_goods_category Data in the data table , And check the contents in the query log .

（1） Insert data into a data table .

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mysql> USE goods;Database changedmysql> INSERT INTO t_goods_category    -> (id, t_category)    -> VALUES    -> (6, ' food ');Query OK, 1 row affected (0.01 sec)

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（2） Data table view .

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mysql> SELECT * FROM t_goods_category;+----+---------------------+| id | t_category          |+----+---------------------+|  1 |  Women's wear / Women's Boutique        ||  2 |  Outdoor sports             ||  3 |  men's wear                 ||  4 |  Children's wear                 ||  5 |  motion                 ||  6 |  food                 |+----+---------------------+6 rows in set (0.01 sec)

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（3） View the contents in the query log .

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[[email protected] ~]# cat /data/mysql/log/general_log/general_statement.log/usr/local/mysql/bin/mysqld, Version: 8.0.18 (binghe edition). started with:Tcp port: 3306  Unix socket: /data/mysql/run/mysql.sockTime                 Id Command    Argument2020-01-17T03:39:34.706121Z         8 Query     SET GLOBAL general_log_file = '/data/mysql/log/general_log/general_statement.log'/usr/local/mysql/bin/mysqld, Version: 8.0.18 (binghe edition). started with:Tcp port: 3306  Unix socket: /data/mysql/run/mysql.sockTime                 Id Command    Argument2020-01-17T03:39:49.435725Z         8 Query     SET GLOBAL log_output = 'file'2020-01-17T03:53:06.278557Z         8 Query     SELECT DATABASE()2020-01-17T03:53:06.278867Z         8 Init DB   goods2020-01-17T03:53:49.479114Z         8 Query     INSERT INTO t_goods_category(id, t_category)VALUES(6, ' food ')2020-01-17T03:54:04.014541Z         8 Query     SELECT * FROM t_goods_category

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The query log records all SQL Statement information .

28.1.3　 Delete the query log

The query log is saved on the server disk in the form of a plain text file . You can delete the query log directly . If you need to re-establish the query log , You need to in MySQL Execute... On the command line FLUSH LOGS Command or execute in the server command line mysqladmin flush-logs command .

（1） Delete the query log .

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rm -rf /data/mysql/log/general_log/general_statement.log

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here , see /data/mysql/log/general_log A file in a directory .

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[[email protected] ~]# ll /data/mysql/log/general_logtotal 0

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Results show , The query log file has been deleted .

（2） Refresh the query log .

Can be in MySQL Execute the following command on the command line to refresh the log .

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mysql> FLUSH LOGS;Query OK, 0 rows affected (0.02 sec)

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You can also execute the following command in the server command line to refresh the log .

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[[email protected] ~]# mysqladmin -uroot -p flush-logsEnter password:

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Log refresh succeeded , Look again /data/mysql/log/general_log A file in a directory .

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[[email protected] ~]# ll /data/mysql/log/general_log total 4-rw-r----- 1 mysql mysql 519 Jan 17 12:33 general_statement.log

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You can see , The query log file has been recreated .

28.1.4　 Close query log

It's easier to turn off the query log , Only need my.cnf Documents or my.ini Of documents [mysqld] Under Options , take general_log The options are configured to 0, Or delete general_log Options .

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[mysqld]general_log = 0

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When the configuration is complete , restart MySQL To take effect .

It can also be in MySQL Execute the following command on the command line to close the query log .

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mysql> SET GLOBAL general_log = 0;Query OK, 0 rows affected (0.00 sec)

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Delete the query log after closing the query log , Then refresh the log ,MySQL The query log file will not be recreated .