16 mysql物理结构-日志文件-慢查询日志

一下是我的操作过程

1. 在my.cnf 中配置 慢查询命令

  [mysqld]章中
log_slow_queries=/tmp/mysqlslow.log  #将要过时


2. 启动

ywx@ywx:/opt/mysql5151$ cat /dev/null > ./data/ywx.errywx 清楚缓冲
@ywx:/opt/mysql5151$ ./bin/mysqld_safe --defaults-file=./my.cnf --user=ywx &   启动
[1] 13825
ywx@ywx:/opt/mysql5151$ 110804 16:57:02 mysqld_safe Logging to '/opt/mysql5151/data/ywx.err'.
110804 16:57:02 mysqld_safe Starting mysqld daemon with databases from /opt/mysql5151/data
ywx@ywx:/opt/mysql5151$

   然后查看 错误日志 ywx.err

我们看到警告，将要过时了，提示我们用 slow_query_log
vim ./data/ywx.err

110804 16:57:02 [Warning] '--log_slow_queries' is deprecated and will be removed in a
future release. Please use ''--slow_query_log'/'--slow_query_log_file'' instead.

所以我们修改 my.cnf 文件
#log_slow_queries=/tmp/mysqlslow.log  #将要过时
slow_query_log=1
slow_query_log_file=/tmp/mysqlslow.log1

登陆数据库

ywx@ywx:/opt/mysql5151$ sudo ./bin/mysql --defaults-file=./my.cnf

查询有关 slow_query  相关的信息

mysql> show variables like '%slow%';
+---------------------+--------------------+
| Variable_name       | Value              |
+---------------------+--------------------+
| log_slow_queries    | ON                 |
| slow_launch_time    | 2                  |
| slow_query_log      | ON                 |
| slow_query_log_file | /tmp/mysqlslow.log | 目录
+---------------------+--------------------+
4 rows in set (0.00 sec)

时间值 默认是10

mysql> show variables like '%long%';
+-----------------+-----------+
| Variable_name   | Value     |
+-----------------+-----------+
| long_query_time | 10.000000 |
+-----------------+-----------+
1 row in set (0.00 sec)

修改时间

mysql> set long_query_time=1;
Query OK, 0 rows affected (0.00 sec)

mysql> set global long_query_time=1;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%long%';
+-----------------+----------+
| Variable_name   | Value    |
+-----------------+----------+
| long_query_time | 1.000000 |
+-----------------+----------+
1 row in set (0.00 sec)

mysql> show variables like '%indexes%';
+-------------------------------+-------+
| Variable_name                 | Value |
+-------------------------------+-------+
| log_queries_not_using_indexes | OFF   |
+-------------------------------+-------+
1 row in set (0.00 sec)