本文实例讲述了mysql表优化、分析、检查和修复的方法。分享给大家供大家参考,具体如下:
这里介绍对数据库的管理常规就是进行预防性的维护,以及修复那些出现问题的内容。
进行检查和修复通常具有四个主要的任务:
1. 对表进行优化
2. 对表进行分析(分析并存储MyISAM和BDB表中键的分布)
3. 对表进行检查(检查表的错误,并且为MyISAM更新键的统计内容)
4. 对表进行修复(修复被破坏的MyISAM表)
一、对表进行优化
优化表有很多方式实现: OPTIMIZE TABLE语句、mysqlcheck工具(服务器要运行)或myisamchk(服务器没有运行或表中没有交互)
为什么优化?随着MySQL的使用,包括BLOB和VARCHAR字节的表将变得比较繁冗,因为这些字段长度不同,对记录进行插入、更新或删除时,会占有不同大小的空间,记录就会变成碎片,且留下空闲的空间。像具有碎片的磁盘,会降低性能,需要整理,因此要优化。
1. 利用OPTIMIZE语句对表进行优化
# mysql>OPTIMIZE TABLE 表名
这样就对表名进行了优化。
2. 利用mysqlcheck对表进行优化
mysqlcheck可进行优化外,还可执行大量的检查和修复任务。
# mysqlcheck -o 数据库名 表名 -uroot -p111111 (一张表) # mysqlcheck -o 数据库名 表名1 表名2 -uroot -p111111 (多张表) # mysqlcheck -o 数据库名 -uroot -p111111 (对整个数据库)
3. 利用myisamchk对表进行优化
# myisamchk --quick --check-only-changed --sort-index --analyze 表名 # myisamchk -r 表名 (参数-r表示对表进行修复,同时也删去了浪费的空间) # myisamchk -r /usr/local/mysql/data/testblog/article (指定表所在的路径)
以上操作需在服务器关闭或没有与服务器互操作的时候,可以使用myisamchk命令行工具(如果服务器正在运行,那么在运行这条语句之前利用mysqladmin flush-tables对表进行刷新。需确保服务器没有与表进行互操作,否则会出现故障)。myisamchk是最老的方法。必须在正确位置上运行myisamchk,或者指定表所在的路径。
注意:在优化过程中,表会被锁住,因此不要在忙时进行优化操作。同样,需要有足够的空间才能进行OPTIMIZE TABLE。如果没有磁盘空间,MySQL将不能进行优化,表也无法使用。
优化是对包含MyISAM表的数据库的常规管理事务中一个重要环节,应该定期进行。
二、对表进行分析
对表的定期分析可以改善性能,且应该成为常规维护工作的一部分。因为通过更新表的索引信息对表进行分析,可改善数据库性能。
有三种方法可以对表进行分析:
1. 连接到MySQL时,使用ANALYZE TABLE语句
2. 利用mysqlcheck命令行工具(服务器需要运行,并且只对MyISAM表起作用)
3. 利用myisamchk命令行工具(服务器不应该运行,或无对所操作的表发生互操作)
# ANALYZE TABLE 表名; # mysqlcheck -a 数据库名 表名 -uroot -p111111 # mysqlcheck -a 数据库名 表名1 表名2 -uroot -p111111
如果试图对不支持分析操作的表进行分析(如InnoDB),那操作将无法进行
# myisamchk -a /usr/local/mysql/data/数据库/表名
更多关于MySQL相关内容感兴趣的读者可查看本站专题:《MySQL事务操作技巧汇总》、《MySQL存储过程技巧大全》、《MySQL数据库锁相关技巧汇总》及《MySQL常用函数大汇总》
希望本文所述对大家MySQL数据库计有所帮助。

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