MySQL数据库中部分数据损坏恢复过程

核心提示： MySQL数据目录不是太难理解的，每一个数据库对应一个子目录，MySQL数据库中部分数据损坏恢复过程(2)，每个子目录中包含了对应于这个数据库中的数据表的文件，每一个数据表对应三个文件，我在Win2003下通过命令提示符，输入：注：此为记录我当时操作的全部过程d:documents and

MySQL数据目录不是太难理解的。每一个数据库对应一个子目录，每个子目录中包含了对应于这个数据库中的数据表的文件。每一个数据表对应三个文件，它们和表名相同，但是具有不同的扩展名。tblname.frm文件是表的定义，它保存了表中包含的数据列的内容和类型。tblname.myd文件包含了表中的数据。tblname.myi文件包含了表的索引(例如，它可能包含lookup表以帮助提高对表的主键列的查询)。 要检查一个表的错误，只需要运行myisamchk(在MySQL的bin目录下)并提供文件的位置和表名，或者是表的索引文件名：

% myisamchk /usr/local/mysql/var/dbname/tblname

% myisamchk /usr/local/mysql/var/dbname/tblname.myi

上面的两个命令都可以执行对指定表的检查。要检查数据库中所有的表，可以使用通配符：

% myisamchk /usr/local/mysql/var/dbname/*.myi

要检查所有数据库中的所有表，可以使用两个通配符：

% myisamchk /usr/local/mysql/var/*/*.myi

如果不带任何选项，myisamchk将对表文件执行普通的检查。如果你对一个表有怀疑，但是普通的检查不能发现任何错误，你可以执行更彻底的检查(但是也更慢！)，这需要使用--extend-check选项：

% myisamchk --extend-check /path/to/tblname

对错误的检查是没有破坏性的，这意味着你不必担心执行对你的数据文件的检查会使已经存在的问题变得更糟。另一方面，修复选项，虽然通常也是安全的，但是它对你的数据文件的更改是无法撤消的。因为这个原因，我们强烈推荐你试图修复一个被破坏的表文件时首先做个备份，并确保在制作这个备份之前你的MySQL服务是关闭的。

我在Win2003下通过命令提示符，输入：

注：此为记录我当时操作的全部过程
d:documents and settingsadministrator>c:
c:>cd MySQL
c:mysql>cd data
c:mysqldata>cd hw_enterprice
c:mysqldatahw_enterprice>myisamchk function_products.frm
'myisamchk' 不是内部或外部命令，也不是可运行的程序或批处理文件。
c:mysqldatahw_enterprice>cd
c:>cd mysql
c:mysql>cd bin
注：查看myisamchk的帮助信息
c:mysqlin>myisamchk
myisamchk　ver 2.6 for win95/win98 at i32
by monty, for your professional use
this software comes with no warranty: see the public for details.
description, check and repair of isam tables.
used without options all tables on the command will be checked for errors
usage: myisamchk [options] tables[.myi]
global options:
-#, --debug=...　　 output debug log. often this is 'd:t:o,filename'
-?, --help　　　　　display this help and exit.
-o, --set-variable var=option
change the value of a variable. please note that
this option is deprecated; you can set variables
directly with '--variable-name=value'.
-t, --tmpdir=path　 path for temporary files
-s, --silent　　　　only print errors.　one can use two -s to make
myisamchk very silent
-v, --verbose　　　 print more information. this can be used with
--description and --check. use many -v for more verbosity!
-v, --version　　　 print version and exit.
-w, --wait　　　　　wait if table is locked.
check options (check is the default action for myisamchk):
-c, --check　　　　 check table for errors
-e, --extend-check　check the table very throughly.　only use this in
extreme cases as myisamchk should normally be able to
find out if the table is ok even without this switch
-f, --fast　　　　　check only tables that haven't been closed properly
-c, --check-only-changed
check only tables that have changed since last check
-f, --force　　　　 restart with '-r' if there are any errors in the table.
states will be updated as with '--update-state'
-i, --information　 print statistics information about table that is checked
-m, --medium-check　faster than extend-check, but only finds 99.99% of
all errors.　should be good enough for most cases
-u　--update-state　mark tables as crashed if you find any errors
-t, --read-only　　 don't mark table as checked
repair options (when using '-r' or '-o')
-b, --backup　　　　make a backup of the .myd file as 'filename-time.bak'
--correct-checksum　correct checksum information for table.
-d, --data-file-length=#　max length of data file (when recreating data
file when it's full)
-e, --extend-check　try to recover every possible row from the data file
normally this will also find a lot of garbage rows;
don't use this option if you are not totally desperate.
-f, --force　　　　 overwrite old temporary files.
-k, --keys-used=#　 tell myisam to update only some specific keys. # is a
bit mask of which keys to use. this can be used to
get faster inserts!
-r, --recover　　　 can fix almost anything except unique keys that aren't
unique.
-n, --sort-recover　forces recovering with sorting even if the temporary
file would be very big.
-p, --parallel-recover
uses the same technique as '-r' and '-n', but creates
all the keys in parallel, in different threads.
this is alpha code. use at your own risk!
-o, --safe-recover　uses old recovery method; slower than '-r' but can
handle a couple of cases where '-r' reports that it
can't fix the data file.
--character-sets-dir=...
directory where character sets are
--set-character-set=name
change the character set used by the index
-q, --quick　　　　 faster repair by not modifying the data file.
one can give a second '-q' to force myisamchk to
modify the original datafile in case of duplicate keys
-u, --unpack　　　　unpack file packed with myisampack.
other actions:
-a, --analyze　　　 analyze distribution of keys. will make some joins in
MySQL faster.　you can check the calculated distribution
by using '--description --verbose table_name'.
-d, --description　 prints some information about table.
-a, --set-auto-increment[=value]
force auto_increment to start at this or higher value
if no value is given, then sets the next auto_increment
value to the highest used value for the auto key + 1.
-s, --sort-index　　sort index blocks.　this speeds up 'read-next' in
applications
-r, --sort-records=#
sort records according to an index.　this makes your
data much more localized and may speed up things
c:mysqlin>myisamchk c:mysqldatahw_enterpricefunction_products.frm
myisamchk: error: 'c:mysqldatahw_enterpricefunction_products.frm' is not a m
yisam-table
c:mysqlin>myisamchk c:mysqldatahw_enterpricefunction_products.myi
checking myisam file: c:mysqldatahw_enterpricefunction_products.myi
data records:　 85207　 deleted blocks:　　　39
myisamchk: warning: table is marked as crashed
myisamchk: warning: 1 clients is using or hasn't closed the table properly
- check file-size
- check key delete-chain
- check record delete-chain
myisamchk: error: record delete-link-chain corrupted
- check index reference
- check data record references index: 1
- check data record references index: 2
- check data record references index: 3
- check record links
myisamchk: error: wrong bytesec: 0-195-171 at linkstart: 841908
myisam-table 'c:MySQLdatahw_enterpricefunction_products.myi' is corrupted
fix it using switch "-r" or "-o"