MySQL数据库下损坏数据的恢复操作

% myisamchk /usr/local/mysql/var/dbName/tblName % myisamchk /usr/local/mysql/var/dbName/tblName.MYI

% myisamchk /usr/local/mysql/var/dbName/*.MYI

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

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

D:\Documents and Settings\Administrator>c: C:\>cd mysql C:\mysql>cd data C:\mysql\data>cd hw_enterprice C:\mysql\data\hw_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:\mysql\data\hw_enterprice>cd\ C:\>cd mysql C:\mysql>cd bin 注：查看myisamchk的帮助信息 C:\mysql\bin>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:\mysql\bin>myisamchk c:\mysql\data\hw_enterprice\function_products.frm myisamchk: error: 'c:\mysql\data\hw_enterprice\function_products.frm' is not a M yISAM-table C:\mysql\bin>myisamchk c:\mysql\data\hw_enterprice\function_products.myi Checking MyISAM file: c:\mysql\data\hw_enterprice\function_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:\mysql\data\hw_enterprice\function_products.myi' is corrupted Fix it using switch "-r" or "-o"

C:\mysql\bin>myisamchk --recover --quick c:\mysql\data\hw_enterprice\function_p roducts.myi - check key delete-chain - check record delete-chain myisamchk: error: record delete-link-chain corrupted myisamchk: error: Quick-recover aborted; Run recovery without switch 'q' Updating MyISAM file: c:\mysql\data\hw_enterprice\function_products.myi MyISAM-table 'c:\mysql\data\hw_enterprice\function_products.myi' is not fixed be cause of errors Try fixing it by using the --safe-recover (-o) or the --force (-f) option

C:\mysql\bin>myisamchk --safe-recover c:\mysql\data\hw_enterprice\function_prod ucts.myi - recovering (with keycache) MyISAM-table 'c:\mysql\data\hw_enterprice\function_ products.myi' Data records: 85207 Wrong bytesec: 0-195-171 at 841908; Skipped Data records: 85215

% myisamchk --recover --quick /path/to/tblName % myisamchk --recover /path/to/tblName % myisamchk --safe-recover /path/to/tblName

mysql> DELETE FROM tblName;