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mysql――slowquerylog_MySQL

时间:2021-07-01 10:21:17 帮助过:8人阅读

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由于最近自己管理的mysql有出现查询慢的情况,为了能够查询出慢查询的sql语句,故启动了mysql的慢查询日志,具体启动慢查询的方法有以下两种:
1、直接登入mysql, 更改mysql参数.(注:登入账号需有管理员权限)
mysql> set global log_slow_queries=on;
mysql> set global slow_query_log_file=/data/mysql.slow.log;
mysql> set global long_query_time=1;
如果是这种方法的话,重启数据库之后就不生效了。
2、直接更改my.conf
[mysqld]
log-slow-queries = /data/mysql.slow.log
long_query_time = 1
我本次使用的是第2种方法,但是重启mysql之后发现慢查询日志没有生效,查询了一下mysql日志,发现日志报如下错误:
110907 18:28:04 InnoDB: Started; log sequence number 0 4245951191
/usr/libexec/mysqld: File '/data/mysql.slow.log' not found (Errcode: 13)
110907 18:28:04 [ERROR] Could not use /data/mysql.slow.log for logging (error 13). Turning logging off for the whole duration of the MySQL server process. To turn it on again: fix the cause, shutdown the MySQL server and restart it.
出现这个情况,一般通过以下操作就可以解决:
touch /data/mysql.slow.log
chown mysql.mysql /data/mysql.slow.log
chmod o-r /data/mysql.slow.log
可是还是不行,再次认真分析了下log发现主要还是/data/mysql.slow.log文件无法找到引起的,但是实际上/data/mysql.slow.log文件是存在的;没办法一下子没找到原因,先把慢查询文件路径改为/var/log/mysql-slow.log试试,这样就行了。
110907 18:39:57 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
110907 18:39:57 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
110907 18:39:57 [Warning] '--log_slow_queries' is deprecated and will be removed in a future release. Please use ''--slow_query_log'/'--slow_query_log_file'' instead.
110907 18:39:57 InnoDB: Started; log sequence number 0 4245951191
110907 18:39:57 [Note] Event Scheduler: Loaded 0 events
110907 18:39:57 [Note] /usr/libexec/mysqld: ready for connections.
Version: '5.1.52-log' socket: '/var/lib/mysql/mysql.sock' port: 3306 Source distribution
[root@localhost log]# ll |grep mysql
-rw-r-----. 1 mysql mysql 512181 Sep 7 18:39 mysqld.log
-rw-r--r--. 1 mysql mysql 422 Sep 7 18:41 mysql-slow.log
[root@localhost log]# cat mysql-slow.log
/usr/libexec/mysqld, Version: 5.1.52-log (Source distribution). started with:
Tcp port: 0 Unix socket: /var/lib/mysql/mysql.sock
Time Id Command Argument
# Time: 110907 18:41:29
# User@Host: root[root] @ localhost []
# Query_time: 1.512086 Lock_time: 0.000001 Rows_sent: 26 Rows_examined: 2443129
use idmanage;
SET timestamp=1315392089;
select type,count(*) from client where status=1 group by type;
经过自己的分析原因应该是:mysql好像不支持跨硬盘写数据。
我的实际情况是这样的,我以前的空间不够用了,然后我再挂了一块硬盘进去了,且新硬盘mount的路径就是/data。
[root@localhost log]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
7.0G 6.6G 12M 100% /
tmpfs 250M 0 250M 0% /dev/shm
/dev/sda1 485M 29M 432M 7% /boot
/dev/mapper/VolGroup-lv_file
485M 11M 449M 3% /file
/dev/sdb1 9.9G 8.1G 1.3G 87% /data

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