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 程式師世界 >> 數據庫知識 >> MYSQL數據庫 >> 關於MYSQL數據庫 >> MySQL中開啟和使用通用查詢日志的實例教程

MySQL中開啟和使用通用查詢日志的實例教程

編輯:關於MYSQL數據庫

開啟通用查詢日志
因為為了性能考慮,一般通用查詢日志general log不會開啟。slow log可以定位一些有性能問題的sql,而general log會記錄所有的SQL。

mysql5.0版本,如果要開啟slow log、general log,需要重啟,從MySQL5.1.6版開始,general query log和slow query log開始支持寫到文件或者數據庫表兩種方式,並且日志的開啟,輸出方式的修改,都可以在Global級別動態修改。

mysql>select version();
+————+
| version() |
+————+
| 5.1.37-log |
+————+
1 row in set (0.02 sec)

設置日志輸出方式為文件(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,這表的默認引擎都是CSV):

mysql>set global log_output=file;
Query OK, 0 rows affected (0.00 sec)

設置general log的日志文件路徑:

mysql>set global general_log_file='/tmp/general.log';
Query OK, 0 rows affected (0.00 sec)

 開啟general log:

mysql>set global general_log=on;
Query OK, 0 rows affected (0.02 sec)

過一段時間後,關閉general log:

mysql>set global general_log=off;
Query OK, 0 rows affected (0.02 sec)

通用查詢日志的系統變量

log_output=[none|file|table|file,table] #通用查詢日志輸出格式
general_log=[on|off]      #是否啟用通用查詢日志

general_log_file[=filename]    #通用查詢日志位置及名字

通用查詢日志的備份

在Linux或Unix中,你可以通過下面的命令重新命名文件

並創建一個新文件:

shell> mv hostname.log hostname-old.log

shell> mysqladmin flush-logs

shell> cp hostname-old.log to-backup-directory

shell> rm hostname-old.log

在Windows中,服務器打開日志文件期間不能重新命名日志文件。必須先停止服務器然後重新命名日志文件。然後重啟服務器來創建新日志文件。

演示通用查詢日志的使用

a、啟用通用查詢日志

--演示環境
root@localhost[(none)]> show variables like '%version%';
+-------------------------+------------------------------+
| Variable_name  | Value  |
+-------------------------+------------------------------+
| innodb_version | 5.5.39  |
| protocol_version | 10   |
| slave_type_conversions |   |
| version  | 5.5.39-log  |
| version_comment | MySQL Community Server (GPL) |
| version_compile_machine | x86_64  |
| version_compile_os | Linux  |
+-------------------------+------------------------------+

--查看系統變量
root@localhost[(none)]> show variables like '%general%';
+------------------+----------------------------+
| Variable_name | Value  |
+------------------+----------------------------+
| general_log | OFF  |
| general_log_file | /var/lib/mysql/suse11b.log |
+------------------+----------------------------+

--查看當前的通用日志,顯示無日志文件
root@localhost[(none)]> system ls /var/lib/mysql/suse11b.log 
ls: cannot access /var/lib/mysql/suse11b.log: No such file or directory
--設置變量general_log以開啟通用查詢日志
root@localhost[(none)]> set @@global.general_log=1;
Query OK, 0 rows affected (0.00 sec)

--再次查看通用日志文件已存在
root@localhost[(none)]> system ls /var/lib/mysql/suse11b.log 
/var/lib/mysql/suse11b.log
root@localhost[(none)]> select * from tempdb.tb1; --執行查詢
+------+------+
| id | val |
+------+------+
| 1 | jack |
+------+------+

--查看通用日志文件內容
root@localhost[(none)]> system more /var/lib/mysql/suse11b.log
/usr/sbin/mysqld, Version: 5.5.39-log (MySQL Community Server (GPL)). started with:
Tcp port: 3306 Unix socket: /var/lib/mysql/mysql.sock
Time  Id Command Argument
141003 16:18:12 4 Query show variables like '%general%'
141003 16:18:55 4 Query select * from tempdb.tb1


b、更改通用查詢日志位置

root@localhost[(none)]> exit
Bye
suse11b:~ # service mysql stop
Shutting down MySQL...   done
suse11b:~ # mysqld --general_log_file=/tmp/suse11b.log --user=mysql &
[1] 47009
suse11b:~ # ps -ef|grep mysql|grep -v grep
mysql 47009 44514 1 16:22 pts/0 00:00:00 mysqld --general_log_file=/tmp/suse11b.log --user=mysql
root 47053 44514 0 16:22 pts/0 00:00:00 grep mysql
suse11b:~ # mysql
root@localhost[(none)]> system ls /tmp/suse11b.log
ls: cannot access /tmp/suse11b.log: No such file or directory

root@localhost[(none)]> show variables like '%gener%';
+------------------+------------------+
| Variable_name | Value |
+------------------+------------------+
| general_log | OFF  |
| general_log_file | /tmp/suse11b.log |
+------------------+------------------+

root@localhost[(none)]> set global general_log=on;
Query OK, 0 rows affected (0.01 sec)

--此時從系統變量看出,通用日志已經到/tmp目錄下
root@localhost[(none)]> show variables like '%gener%';
+------------------+------------------+
| Variable_name | Value |
+------------------+------------------+
| general_log | ON  |
| general_log_file | /tmp/suse11b.log |
+------------------+------------------+

--發布查詢
root@localhost[(none)]> select count(*) from tempdb.tb1;
+----------+
| count(*) |
+----------+
| 1 |
+----------+

--查看通用日志文件內容
root@localhost[(none)]> system more /tmp/suse11b.log
mysqld, Version: 5.5.39-log (MySQL Community Server (GPL)). started with:
Tcp port: 3306 Unix socket: /var/lib/mysql/mysql.sock
Time  Id Command Argument
141003 16:30:03 1 Query show variables like '%gener%'
141003 16:30:09 1 Query select count(*) from tempdb.tb1


c、通用查詢日志輸出方式

--可以輸出為文件,表以及不輸出,即TABLE,FILE,NONE
--系統變量log_output
root@localhost[(none)]> show variables like 'log_output';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_output | FILE |
+---------------+-------+

--下面修改為輸出為表方式
root@localhost[(none)]> set global log_output='TABLE';
Query OK, 0 rows affected (0.00 sec)

root@localhost[(none)]> show variables like 'log_output';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_output | TABLE |
+---------------+-------+

--發布查詢
root@localhost[(none)]> select * from tempdb.tb1;
+------+------+
| id | val |
+------+------+
| 1 | jack |
+------+------+

root@localhost[(none)]> system more /tmp/suse11b.log
mysqld, Version: 5.5.39-log (MySQL Community Server (GPL)). started with:
Tcp port: 3306 Unix socket: /var/lib/mysql/mysql.sock
Time  Id Command Argument
141003 16:30:03 1 Query show variables like '%gener%'
141003 16:30:09 1 Query select count(*) from tempdb.tb1
141003 16:31:00 1 Query show variables like 'log_output'
141003 17:00:48 1 Query set global log_output='TABLE' #通用查詢日志輸出到文件僅僅記錄到全局變量的修改

--mysql.general_log記錄了通用查詢日志的信息
root@localhost[(none)]> desc mysql.general_log;
+--------------+------------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default  | Extra  |
+--------------+------------------+------+-----+-------------------+-----------------------------+
| event_time | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| user_host | mediumtext | NO | | NULL  |  |
| thread_id | int(11) | NO | | NULL  |  |
| server_id | int(10) unsigned | NO | | NULL  |  |
| command_type | varchar(64) | NO | | NULL  |  |
| argument | mediumtext | NO | | NULL  |  |
+--------------+------------------+------+-----+-------------------+-----------------------------+

--從通用查詢日志表裡查看通用查詢日志的內容
root@localhost[(none)]> select thread_id,command_type,argument from mysql.general_log; 
+-----------+--------------+---------------------------------------------------------------+
| thread_id | command_type | argument    |
+-----------+--------------+---------------------------------------------------------------+
| 1 | Query | show variables like 'log_output'   |
| 1 | Query | select * from tempdb.tb1   |
| 1 | Query | desc mysql.general_log   |
| 1 | Query | select thread_id,command_type,argument from mysql.general_log |
+-----------+--------------+---------------------------------------------------------------+

root@localhost[(none)]> show variables like 'log_output';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_output | TABLE |
+---------------+-------+

--使用FILE,TABLE 2者混合輸出通用日志
root@localhost[(none)]> set global log_output='file,table';
Query OK, 0 rows affected (0.00 sec)

root@localhost[(none)]> select @@global.log_output;
+---------------------+
| @@global.log_output |
+---------------------+
| FILE,TABLE |
+---------------------+

root@localhost[(none)]> insert into tempdb.tb1 values(2,'robinson');
Query OK, 1 row affected (0.06 sec)

root@localhost[(none)]> commit;
Query OK, 0 rows affected (0.01 sec)

--驗證結果,表和文件裡邊存在通用的日志記錄
root@localhost[(none)]> system tail /tmp/suse11b.log|grep robinson
141003 17:41:54 2 Query insert into tempdb.tb1 values(2,'robinson')
root@localhost[(none)]> select thread_id,command_type,argument from mysql.general_log
 -> where argument like '%robinson%';
+-----------+--------------+------------------------------------------------------------------------+
| thread_id | command_type | argument     |
+-----------+--------------+------------------------------------------------------------------------+
| 2 | Query | insert into tempdb.tb1 values(2,'robinson')  |
| 2 | Query | select thread_id,command_type,argument from mysql.general_log |
|  |  | where argument like ''robinson''   | 
+-----------+--------------+------------------------------------------------------------------------+


d、關閉通用查詢日志

--可以通過設置系統變量general_log來關閉通用查詢日志,此時日志輸出設置為FILE,TABLE
root@localhost[(none)]> show variables like 'log_output';
+---------------+------------+
| Variable_name | Value |
+---------------+------------+
| log_output | FILE,TABLE |
+---------------+------------+

root@localhost[(none)]> set global general_log=off;
Query OK, 0 rows affected (0.01 sec)

root@localhost[(none)]> show variables like '%gener%';
+------------------+------------------+
| Variable_name | Value |
+------------------+------------------+
| general_log | OFF  |
| general_log_file | /tmp/suse11b.log |
+------------------+------------------+

root@localhost[(none)]> delete from tempdb.tb1 where id=2;
Query OK, 1 row affected (0.12 sec)

root@localhost[(none)]> commit;
Query OK, 0 rows affected (0.00 sec)

root@localhost[(none)]> system tail -n 1 /tmp/suse11b.log
141003 17:45:13 2 Query set global general_log=off

root@localhost[(none)]> select thread_id,command_type,argument from mysql.general_log
 -> where argument like '%delete%';
Empty set (0.00 sec)

--從上面的演示可知,盡管我們設置了log_output為FILE,TABLE,但general_log為OFF,通用日志無任何記錄產生

root@localhost[(none)]> set global log_output=none;
Query OK, 0 rows affected (0.00 sec)

root@localhost[(none)]> set global general_log=1;
Query OK, 0 rows affected (0.00 sec)

root@localhost[(none)]> truncate table tempdb.tb1;
Query OK, 0 rows affected (0.01 sec)

root@localhost[(none)]> system tail -n 1 /tmp/suse11b.log
Time  Id Command Argument

--通過上面的演示,在log_output=none,general_log=on的清下下無任何通用日志輸出。

 

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