MySQL中的通用查詢日志(General Query Log)

1. 以什么形式來記錄？
log_output系統變量來決定的，可選值 TABLE, FILE, 或者 NONE，默認值是FILE，可以同時選擇TABLE和FILE，中間用逗號隔開。

2. 如何開啟？
設置general_log系統變量，設置為ON,OFF

3. 具體寫到哪里？
如果是寫到文件里，由general_log_file指定，如果要看默認值，可以使用show variables like 'general_log_file'。如果寫到表里，則寫到mysql.general_log

4. 何時開啟？
可以在啟動MySQL server的時候開啟，指定--log_output，--general_log和--general_log_file選項；也可以在運行時開啟，設置環境變量log_output，general_log和general_log_file

5. 記錄什么內容？

The server writes information to this log when clients connect or disconnect, and it logs each SQL statement received from clients.

測試：
下面的測試中分別從db2b和db2a上連接了MySQL數據庫，并進行了一些增、刪、改、查的動作，看一下通用查詢日志記錄了哪些內容：
db2a為MySQL server:

mysql> set global general_log=1;
mysql> show variables like 'general_log_file';
+------------------+-------------------------+
| Variable_name | Value |
+------------------+-------------------------+
| general_log_file | /var/lib/mysql/db2a.log |
+------------------+-------------------------+
1 row in set (0.04 sec)

mysql> alter user 'user1'@'db2b' identified by 'user1';

db2b上：
root@db2b:~# mysql -h db2a -u user1 -pwrong sample
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1045 (28000): Access denied for user 'user1'@'db2b' (using password: YES)
root@db2b:~# mysql -h db2a -u user1 -puser1 sample
mysql> drop table test1;
mysql> create table test1(year);
mysql> create table test1(year int);
mysql> insert into test1 values(2007),(2010);
mysql> select * from test1 where year > 2008;
mysql> delete from test1 where year < 2008;
mysql> show variables like 'default_password_lifetime';
mysql> quit

db2a上：
root@db2a:~# mysql -u root -pqingsong sample;
mysql> select * from test2;
mysql> set global general_log=0;

看一下 cat /var/lib/mysql/db2a.log

root@db2a:~# cat /var/lib/mysql/db2a.log mysqld, Version: 5.7.18-log (MySQL Community Server (GPL)). started with: Tcp port: 3306 Unix socket: /var/run/mysqld/mysqld.sock Time Id Command Argument 2017-09-18T12:26:25.428531Z 16 Query show variables like 'general_log_file' 2017-09-18T12:26:32.415259Z 16 Query ALTER USER 'user1'@'db2b' IDENTIFIED WITH 'mysql_native_password' AS '<secret>' 2017-09-18T12:26:41.703283Z 23 Connect user1@db2b on sample using SSL/TLS 2017-09-18T12:26:41.703388Z 23 Connect Access denied for user 'user1'@'db2b' (using password: YES) 2017-09-18T12:26:50.012271Z 24 Connect user1@db2b on sample using SSL/TLS 2017-09-18T12:26:50.049494Z 24 Query show databases 2017-09-18T12:26:50.055891Z 24 Query show tables 2017-09-18T12:26:50.068155Z 24 Field List A 2017-09-18T12:26:50.084237Z 24 Field List B 2017-09-18T12:26:50.084982Z 24 Field List child 2017-09-18T12:26:50.085600Z 24 Field List employee 2017-09-18T12:26:50.086364Z 24 Field List s2 2017-09-18T12:26:50.087536Z 24 Field List t1 2017-09-18T12:26:50.088150Z 24 Field List t2 2017-09-18T12:26:50.088679Z 24 Field List test1 2017-09-18T12:26:50.089221Z 24 Field List test2 2017-09-18T12:26:50.091282Z 24 Query select @@version_comment limit 1 2017-09-18T12:26:56.784946Z 24 Query drop table test1 2017-09-18T12:27:08.058195Z 24 Query create table test1(year int) 2017-09-18T12:27:12.764736Z 24 Query insert into test1 values(2007),(2010) 2017-09-18T12:27:16.740802Z 24 Query select * from test1 where year > 2008 2017-09-18T12:27:22.588631Z 24 Query delete from test1 where year < 2008 2017-09-18T12:27:26.476919Z 24 Query show variables like 'default_password_lifetime' 2017-09-18T12:27:29.008515Z 24 Quit 2017-09-18T12:28:09.577592Z 25 Connect root@localhost on sample using Socket 2017-09-18T12:28:09.638443Z 25 Query show databases 2017-09-18T12:28:09.660399Z 25 Query show tables 2017-09-18T12:28:09.661135Z 25 Field List A 2017-09-18T12:28:09.661638Z 25 Field List B 2017-09-18T12:28:09.662730Z 25 Field List child 2017-09-18T12:28:09.663875Z 25 Field List employee 2017-09-18T12:28:09.665264Z 25 Field List s2 2017-09-18T12:28:09.666117Z 25 Field List t1 2017-09-18T12:28:09.666671Z 25 Field List t2 2017-09-18T12:28:09.667845Z 25 Field List test1 2017-09-18T12:28:09.668325Z 25 Field List test2 2017-09-18T12:28:09.668993Z 25 Query select @@version_comment limit 1 2017-09-18T12:28:23.349771Z 25 Query select * from test2 2017-09-18T12:28:27.891398Z 25 Query set global general_log=0
可以看到，執行的drop/create table， select/insert/update/delete，show variables，set，以及連接動作(成功與否)/退出都被記錄了下來。

參考鏈接：
https://dev.mysql.com/doc/refman/5.7/en/log-destinations.html
https://dev.mysql.com/doc/refman/5.7/en/query-log.html

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