7.6.2 How to Check MyISAM Tables for Errors
To check a
MyISAM table, use the following commands:
This finds 99.99% of all errors. What it cannot find is corruption that involves only the data file (which is very unusual). If you want to check a table, you should normally run myisamchk without options or with the
This finds 99.999% of all errors. It first checks all index entries for errors and then reads through all rows. It calculates a checksum for all key values in the rows and verifies that the checksum matches the checksum for the keys in the index tree.
This does a complete and thorough check of all data (
-emeans “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 for a large table that has many indexes. Normally, myisamchk stops after the first error it finds. If you want to obtain more information, you can add the
-v(verbose) option. This causes myisamchk to keep going, up through a maximum of 20 errors.
This is like the previous command, but the
-ioption tells myisamchk to print additional statistical information.
In most cases, a simple myisamchk command with no arguments other than the table name is sufficient to check a table.