MySQL配置优化(一)――慢查日志 - 数据库编程

(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:~#