4.4.6.8 How to Check Tables for Errors

To check a MyISAM table, use the following commands:

myisamchk tbl_name

This finds 99.99% of all errors. What it can't find is corruption that involves only the datafile (which is very unusual). If you want to check a table, you should normally run myisamchk without options or with either the -s or --silent option.

myisamchk -m tbl_name

This finds 99.999% of all errors. It checks first all index entries for errors and then it reads through all rows. It calculates a checksum for all keys in the rows and verifies that they checksum matches the checksum for the keys in the index tree.

myisamchk -e tbl_name

This does a complete and thorough check of all data (-e means ``extended check''). It does a check-read of every key for each row to verify that they indeed point to the correct row. This may take a long time on a big table with many keys. myisamchk will normally stop after the first error it finds. If you want to obtain more information, you can add the --verbose (-v) option. This causes myisamchk to keep going, up through a maximum of 20 errors. In normal usage, a simple myisamchk (with no arguments other than the table name) is sufficient.

myisamchk -e -i tbl_name

Like the previous command, but the -i option tells myisamchk to print some informational statistics, too.

User Comments

Add your own comment.