mysql查询日志指的是什么意思

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1、查询日志记录了客户端的所有操作语句，二进制不包含查询数据的sql语句。

2、查询日志记录服务器收到的每一个查询或命令。无论这些查询或命令是否正确，甚至是否包含语法错误，查询日志都会记录下来。

记录格式为{Time、Id、Command、Argument}。也正是因为mysql服务器需要不断记录日志，打开查询日志会产生很大的系统费用。因此，Mysql默认关闭查询日志。

实例

a、启用通用查询日志--演示环境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                        |+-------------------------+------------------------------+ --查看系统变量root@localhost[(none)]> show variables like '%general%';+------------------+----------------------------+| Variable_name    | Value                      |+------------------+----------------------------+| general_log      | OFF                        || general_log_file | /var/lib/mysql/suse11b.log |+------------------+----------------------------+ --查看当前的通用日志，显示无日志文件root@localhost[(none)]> system ls /var/lib/mysql/suse11b.logls: cannot access /var/lib/mysql/suse11b.log: No such file or directory--设置变量general_log以开启通用查询日志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.logroot@localhost[(none)]> select * from tempdb.tb1;  --执行查询+------+------+| id   | val  |+------+------+|    1 | jack |+------+------+ --查看通用日志文件内容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.sockTime                 Id Command    Argument141003 16:18:12     4 Query     show variables like '%general%'141003 16:18:55     4 Query     select * from tempdb.tb1  b、更改通用查询日志位置root@localhost[(none)]> exitByesuse11b:~ # service mysql stopShutting down MySQL...                                          donesuse11b:~ # mysqld --general_log_file=/tmp/suse11b.log --user=mysql &[1] 47009suse11b:~ # ps -ef|grep mysql|grep -v grepmysql    47009 44514  1 16:22 pts/0    00:00:00 mysqld --general_log_file=/tmp/suse11b.log --user=mysqlroot     47053 44514  0 16:22 pts/0    00:00:00 grep mysqlsuse11b:~ # mysqlroot@localhost[(none)]> system ls /tmp/suse11b.logls: cannot access /tmp/suse11b.log: No such file or directoryroot@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) --此时从系统变量看出，通用日志已经到/tmp目录下root@localhost[(none)]> show variables like '%gener%';+------------------+------------------+| Variable_name    | Value            |+------------------+------------------+| general_log      | ON               || general_log_file | /tmp/suse11b.log |+------------------+------------------+ --发布查询root@localhost[(none)]> select count(*) from tempdb.tb1;+----------+| count(*) |+----------+|        1 |+----------+ --查看通用日志文件内容root@localhost[(none)]> system more /tmp/suse11b.logmysqld, Version: 5.5.39-log (MySQL Community Server (GPL)). started with:Tcp port: 3306  Unix socket: /var/lib/mysql/mysql.sockTime                 Id Command    Argument141003 16:30:03     1 Query     show variables like '%gener%'141003 16:30:09     1 Query     select count(*) from tempdb.tb1  c、通用查询日志输出方式--可以输出为文件，表以及不输出，即TABLE，FILE，NONE--系统变量log_outputroot@localhost[(none)]> show variables like 'log_output';+---------------+-------+| Variable_name | Value |+---------------+-------+| log_output    | FILE  |+---------------+-------+ --下面修改为输出为表方式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 |+---------------+-------+ --发布查询root@localhost[(none)]> select * from tempdb.tb1;+------+------+| id   | val  |+------+------+|    1 | jack |+------+------+ --Author: Leshami--Blog  : http://blog.csdn.net/leshami root@localhost[(none)]> system more /tmp/suse11b.logmysqld, Version: 5.5.39-log (MySQL Community Server (GPL)). started with:Tcp port: 3306  Unix socket: /var/lib/mysql/mysql.sockTime                 Id Command    Argument141003 16:30:03     1 Query     show variables like '%gener%'141003 16:30:09     1 Query     select count(*) from tempdb.tb1141003 16:31:00     1 Query     show variables like 'log_output'141003 17:00:48     1 Query     set global log_output='TABLE'  #通用查询日志输出到文件仅仅记录到全局变量的修改 --mysql.general_log记录了通用查询日志的信息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              |                             |+--------------+------------------+------+-----+-------------------+-----------------------------+ --从通用查询日志表里查看通用查询日志的内容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者混合输出通用日志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) --验证结果，表和文件里边存在通用的日志记录root@localhost[(none)]> system tail /tmp/suse11b.log|grep robinson141003 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、关闭通用查询日志--可以通过设置系统变量general_log来关闭通用查询日志，此时日志输出设置为FILE,TABLEroot@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.log141003 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) --从上面的演示可知，尽管我们设置了log_output为FILE,TABLE，但general_log为OFF，通用日志无任何记录产生 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.logTime                 Id Command    Argument --通过上面的演示，在log_output=none,general_log=on的清下下无任何通用日志输出。

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