mysql myisamchk修复数据库常用命令记录

作者：袖梨 2022-11-14

实例

代码如下

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#locate myisamchk

#ln -s /usr/local/mysql/bin/myisamchk /usr/bin/myisamchk

#myisamchk tablename.MYI

#myisamchk -r -q tablename

如果-r不行就采用强制执行命令如下

代码如下	复制代码
#myisamchk -r -o -f

好了根据上面我们来分享一个实例

MyISAM是MySQL的预设storage engine. MyISAM table很容易烂掉(corrupted)。
此文章将教你如何检查/修?驼庑├玫舻?yISAM tables.

每次你在MySQL DB ?造一个 table，将会在档案系统上同时?造出*.frm、*.MYD，跟*.MYI等三种格式的档案。

*.frm = 用来储存资料表格式(file to store table format)
*.MYD(MyData) = 用来储存资料(file to store data)
*.MYI(MyIndex) =用来储存索引(file to store index)

如何检查DB?哪个table 需要修?停?/p>

用root 执行以下指令，假设要检查DB1下的各个table

代码如下	复制代码
#myisamchk /var/lib/mysql/DB1/*.MYI >> /tmp/myisamchk.log

萤幕输出中，如果发现以下字样，该资料表就应修??/p>

代码如下

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myisamchk: error: Keypointers and record positions doesn't match
MyISAM-table '/var/lib/mysql/DB1/news_post_comment.MYI' is corrupted
Fix it using switch "-r" or "-o"
myisamchk: warning: 1 client is using or hasn't closed the table properly
MyISAM-table '/var/lib/mysql/DB1/news_post.MYI' is usable but should be fixed
myisamchk: warning: 1 client is using or hasn't closed the table properly
MyISAM-table '/var/lib/mysql/DB1/news_post_push_log.MYI' is usable but should be fixed

Redirect出来的档案中会显示更多资讯。如下

代码如下	复制代码
Checking MyISAM file: /var/lib/mysql/DB1/yam_bbauth.MYI Data records: 14 Deleted blocks: 0 - check file-size - check record delete-chain - check key delete-chain - check index reference - check data record references index: 1 - check record links

如何利用myisamchk修?屠玫舻?ables：

找出烂掉的table之后，用以下指令修?停?/p>

代码如下	复制代码
#myisamchk –r /var/lib/mysql/DB1/news_post_comment.MYI - recovering (with sort) MyISAM-table '/var/lib/mysql/DB1/news_post_comment.MYI Data records: 1 - Fixing index 1

如果table正被某个application使用，你可能会看到： clients are using or haven't closed the table properly。
所以建议修?颓敖?ysqld关掉或用FLUSH TABLES锁住TABLES，防止修?褪庇?pplication对DB TABLE做更动。

如何让检查跟修?屯?苯?校?/p>

代码如下	复制代码
#myisamchk --silent --force --fast --update-state /var/lib/mysql/DB1/*.MYI myisamchk: MyISAM file /var/lib/mysql/DB1/groups.MYI myisamchk: warning: 1 client is using or hasn't closed the table properly myisamchk: MyISAM file /var/lib/mysql/DB1/profiles.MYI myisamchk: warning: 1 client is using or hasn't closed the table properly

options 的意义如下：
? s, –silent option: Prints only errors. You can use two -s to make myisamchk very silent.
? -f, –force option: Restart myisamchk automatically with repair option -r, if there are any errors in the table.
? -F, –fast option: Check only tables that haven't been closed properly.
? -U –update-state option: Marks tables as crashed, when it finds any error.

修?褪笔侄?峙浼且涮甯?哟蟮?B

庞大的table，修?托枰?艹さ氖奔洹Ｐ?褪笨梢允侄?黾蛹且涮宀问??/p>

代码如下	复制代码
# myisamchk --silent --force --fast --update-state --key_buffer_size=512M --sort_buffer_size=512M --read_buffer_size=4M --write_buffer_size=4M /var/lib/mysql/DB1/*.MYI

用myisamchk 获取table资讯

代码如下

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#myisamchk -dvv profiles.MYI
MyISAM file: profiles.MYI
Record format: Packed
Character set: latin1_swedish_ci (8)
File-version: 1
Creation time: 2007-08-16 18:46:59
Status: open,changed,analyzed,optimized keys,sorted index pages
Auto increment key: 1 Last value: 88
Data records: 88 Deleted blocks: 0
Datafile parts: 118 Deleted data: 0
Datafile pointer (bytes): 4 Keyfile pointer (bytes): 4
Datafile length: 6292 Keyfile length: 6144
Max datafile length: 4294967294 Max keyfile length: 4398046510079
Recordlength: 2124

table description:
Key Start Len Index Type Rec/key Root Blocksize
1 2 3 unique int24 1 1024 1024
2 5 765 unique char packed stripped 1 2048 4096

Field Start Length Nullpos Nullbit Type