REPAIR TABLE
Posted by admin on January 20 2007 23:30:59

REPAIR TABLE



REPAIR TABLE repairs a possibly corrupted table. By default, it has the same effect as myisamchk --recover tbl_name. REPAIR TABLE works for MyISAM and for ARCHIVE tables. See Section 14.1, “The MyISAM Storage Engine”, and Section 14.8, “The ARCHIVE Storage Engine”.

This statement requires SELECT and INSERT privileges for the table.

Normally, you should never have to run this statement. However, if disaster strikes, REPAIR TABLE is very likely to get back all your data from a MyISAM table. If your tables become corrupted often, you should try to find the reason for it, to eliminate the need to use REPAIR TABLE. See Section B.4.2, “What to Do If MySQL Keeps Crashing”, and Section 14.1.4, “MyISAM Table Problems”.

Warning: If the server dies during a REPAIR TABLE operation, it is essential after restarting it that you immediately execute another REPAIR TABLE statement for the table before performing any other operations on it. (It is always a good idea to start by making a backup.) In the worst case, you might have a new clean index file without information about the data file, and then the next operation you perform could overwrite the data file. This is an unlikely but possible scenario.

REPAIR TABLE returns a result set with the following columns:

ColumnValue
TableThe table name
OpAlways repair
Msg_typeOne of status, error, info, or warning
Msg_textThe message

The REPAIR TABLE statement might produce many rows of information for each repaired table. The last row has a Msg_type value of status and Msg_test normally should be OK. If you do not get OK, you should try repairing the table with myisamchk --safe-recover. (REPAIR TABLE does not yet implement all the options of myisamchk.) With myisamchk --safe-recover, you can also use options that REPAIR TABLE does not support, such as --max-record-length.

If QUICK is given, REPAIR TABLE tries to repair only the index tree. This type of repair is like that done by myisamchk --recover --quick.

If you use EXTENDED, MySQL creates the index row by row instead of creating one index at a time with sorting. This type of repair is like that done by myisamchk --safe-recover.

There is also a USE_FRM mode available for REPAIR TABLE. Use this if the .MYI index file is missing or if its header is corrupted. In this mode, MySQL re-creates the .MYI file using information from the .frm file. This kind of repair cannot be done with myisamchk. Note: Use this mode only if you cannot use regular REPAIR modes. The .MYI header contains important table metadata (in particular, current AUTO_INCREMENT value and Delete link) that are lost in REPAIR ... USE_FRM. Don't use USE_FRM if the table is compressed because this information is also stored in the .MYI file.

REPAIR TABLE statements are written to the binary log unless the optional NO_WRITE_TO_BINLOG keyword (or its alias LOCAL) is used. This is done so that REPAIR TABLE statements used on a MySQL server acting as a replication master will be replicated by default to the replication slave.

MySQL Berkley tables cannot be repaired using
REPAIR TABLE. However, after a BIG hardware
crash, I was able to recover data that I thought
had been lost by;
1) Shutting down all clients
2) Reloading the database (using mysqladmin
reload) then 3) Shutting down and restarting the
mySQL server.

I am truly amazed. :)) Well done guys!