4.4.6.4 Repair Options for myisamchk

The following options are used if you start myisamchk with -r or -o:

-D # or --data-file-length=#

Max length of datafile (when re-creating datafile when it's 'full').

-e or --extend-check

Try to recover every possible row from the datafile. Normally this will also find a lot of garbage rows. Don't use this option if you are not totally desperate.

-f or --force

Overwrite old temporary files (table_name.TMD) instead of aborting.

-k # or keys-used=#

If you are using ISAM, tells the ISAM storage engine to update only the first # indexes. If you are using MyISAM, tells which keys to use, where each binary bit stands for one key (first key is bit 0). This can be used to get faster inserts! Deactivated indexes can be reactivated by using myisamchk -r. keys.

-l or --no-symlinks

Do not follow symbolic links. Normally myisamchk repairs the table a symlink points at. This option doesn't exist in MySQL 4.0, as MySQL 4.0 will not remove symlinks during repair.

-r or --recover

Can fix almost anything except unique keys that aren't unique (which is an extremely unlikely error with ISAM/MyISAM tables). If you want to recover a table, this is the option to try first. Only if myisamchk reports that the table can't be recovered by -r, you should then try -o. (Note that in the unlikely case that -r fails, the datafile is still intact.) If you have lots of memory, you should increase the size of sort_buffer_size!

-o or --safe-recover

Uses an old recovery method (reads through all rows in order and updates all index trees based on the found rows); this is an order of magnitude slower than -r, but can handle a couple of very unlikely cases that -r cannot handle. This recovery method also uses much less disk space than -r. Normally one should always first repair with -r, and only if this fails use -o. If you have lots of memory, you should increase the size of key_buffer_size!

-n or --sort-recover

Force myisamchk to use sorting to resolve the keys even if the temporary files should be very big.

--character-sets-dir=...

Directory where character sets are stored.

--set-character-set=name

Change the character set used by the index

-t or --tmpdir=path

Path for storing temporary files. If this is not set, myisamchk will use the environment variable TMPDIR for this. Starting from MySQL 4.1, tmpdir can be set to a list of paths separated by colon : (semicolon ; on Windows). They will be used in round-robin fashion.

-q or --quick

Faster repair by not modifying the datafile. One can give a second -q to force myisamchk to modify the original datafile in case of duplicate keys

-u or --unpack

Unpack file packed with myisampack.

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