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MySQL配置优化(一)慢查日志_MySQL

时间:2021-07-01 10:21:17 帮助过:29人阅读

(1) ERRLOG

包含了当mysqd启动和停止时,以及服务器在运行过程中发生任何严重错误时的相 关信息;

可以用–log-error[=file_name]选项来指定mysqld保存错误日志文件的位置。如果没有给定file_name值,mysqld使用错误日志名host_name.err 并在数据目录中写入日志文件;

# * Logging and Replication
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
# general_log_file        = /var/log/mysql/mysql.log fg
# general_log             = 1
# Error log - should be very few entries.
log_error = /var/log/mysql/error.log

(2)BINLOG

二进制日志包含了所有更新了数据或者已经潜在更新了数据(例如,没有匹配任何
行的一个DELETE)的所有语句。语句以“事件”的形式保存,它描述数据更改;

root@kallen:/# mysqlbinlog log-file 
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/; 
/*!40019 SET @@session.max_insert_delayed_threads=0*/; 
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/; 
DELIMITER /*!*/; 
mysqlbinlog: File 'log-file' not found (Errcode: 2) 
DELIMITER ; 
# End of log file 
ROLLBACK /* added by mysqlbinlog */; 
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/; ddkosooodfdsfsfs
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/; 
root@kallen:/#

(3) 慢查询日志

记录包含所有执行时间超过long_query_time秒的SQL语句的日志文件。获得初使表 锁定的时间不算作执行时间。

用–log-slow-queries[=file_name]选项启动它。如果没有给出file_name值, 默认为主机名,后缀为-slow.log。如果给出了文件名,但不是绝对路径名,文件则写 入数据目录。

root@kallen:/var/log/mysql# mysqldumpslow log-file
root@kallen:~# mysqldumpslow /var/log/mysql/mysql-slow.log 
Reading mysql slow query log from /var/log/mysql/mysql-slow.log 
Count: 1 Time=0.88s (0s) Lock=0.00s (0s) Rows=0.0 (0), debian-sys-maint[debian-sys-maint]@localhost 
select count(*) into @discard from `information_schema`.`COLUMNS` 

Count: 1 Time=0.16s (0s) Lock=0.00s (0s) Rows=35.0 (35), debian-sys-maint[debian-sys-maint]@localhost 
select concat('S', 
TABLE_SCHEMA, 'S', TABLE_NAME, 'S') 
from information_schema.TABLES where ENGINE='S' 
root@kallen:~#

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