REPAIR [NO_WRITE_TO_BINLOG | LOCAL]
TABLE tbl_name [, tbl_name] ...
[QUICK] [EXTENDED] [USE_FRM]
REPAIR TABLE
repairs a possibly
corrupted table, for certain storage engines only.
This statement requires SELECT
and INSERT
privileges for the
table.
Although normally you should never have to run
REPAIR TABLE
, if disaster
strikes, this statement is very likely to get back all your data
from a MyISAM
table. If your tables become
corrupted often, try to find the reason for it, to eliminate the
need to use REPAIR TABLE
. See
Section B.3.3.3, “What to Do If MySQL Keeps Crashing”, and
Section 18.2.4, “MyISAM Table Problems”.
REPAIR TABLE
checks the table to
see whether an upgrade is required. If so, it performs the
upgrade, following the same rules as
CHECK TABLE ... FOR
UPGRADE
. See Section 15.7.3.2, “CHECK TABLE Statement”, for more
information.
Make a backup of a table before performing a table repair operation; under some circumstances the operation might cause data loss. Possible causes include but are not limited to file system errors. See Chapter 9, Backup and Recovery.
If the server exits during a
REPAIR TABLE
operation, it is essential after restarting it that you immediately execute anotherREPAIR TABLE
statement for the table before performing any other operations on it. 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 that underscores the value of making a backup first.In the event that a table on the source becomes corrupted and you run
REPAIR TABLE
on it, any resulting changes to the original table are not propagated to replicas.
REPAIR TABLE
works for
MyISAM
,
ARCHIVE
, and
CSV
tables. For
MyISAM
tables, it has the same
effect as myisamchk --recover
tbl_name
by default. This
statement does not work with views.
REPAIR TABLE
is supported for
partitioned tables. However, the USE_FRM
option cannot be used with this statement on a partitioned
table.
You can use ALTER TABLE ... REPAIR
PARTITION
to repair one or more partitions; for more
information, see Section 15.1.9, “ALTER TABLE Statement”, and
Section 26.3.4, “Maintenance of Partitions”.
NO_WRITE_TO_BINLOG
orLOCAL
By default, the server writes
REPAIR TABLE
statements to the binary log so that they replicate to replicas. To suppress logging, specify the optionalNO_WRITE_TO_BINLOG
keyword or its aliasLOCAL
.QUICK
If you use the
QUICK
option,REPAIR TABLE
tries to repair only the index file, and not the data file. This type of repair is like that done by myisamchk --recover --quick.EXTENDED
If you use the
EXTENDED
option, 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.USE_FRM
The
USE_FRM
option is available for use if the.MYI
index file is missing or if its header is corrupted. This option tells MySQL not to trust the information in the.MYI
file header and to re-create it using information from the data dictionary. This kind of repair cannot be done with myisamchk.CautionUse the
USE_FRM
option only if you cannot use regularREPAIR
modes. Telling the server to ignore the.MYI
file makes important table metadata stored in the.MYI
unavailable to the repair process, which can have deleterious consequences:The current
AUTO_INCREMENT
value is lost.The link to deleted records in the table is lost, which means that free space for deleted records remains unoccupied thereafter.
The
.MYI
header indicates whether the table is compressed. If the server ignores this information, it cannot tell that a table is compressed and repair can cause change or loss of table contents. This means thatUSE_FRM
should not be used with compressed tables. That should not be necessary, anyway: Compressed tables are read only, so they should not become corrupt.
If you use
USE_FRM
for a table that was created by a different version of the MySQL server than the one you are currently running,REPAIR TABLE
does not attempt to repair the table. In this case, the result set returned byREPAIR TABLE
contains a line with aMsg_type
value oferror
and aMsg_text
value ofFailed repairing incompatible .FRM file
.If
USE_FRM
is used,REPAIR TABLE
does not check the table to see whether an upgrade is required.
REPAIR TABLE
returns a result
set with the columns shown in the following table.
Column | Value |
---|---|
Table |
The table name |
Op |
Always repair |
Msg_type |
status , error ,
info , note , or
warning |
Msg_text |
An informational 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
. For a
MyISAM
table, if you do not get
OK
, you should try repairing it with
myisamchk --safe-recover.
(REPAIR TABLE
does not
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
.)
REPAIR TABLE
table catches and
throws any errors that occur while copying table statistics
from the old corrupted file to the newly created file. For
example. if the user ID of the owner of the
.MYD
or .MYI
file is
different from the user ID of the mysqld
process, REPAIR TABLE
generates
a "cannot change ownership of the file" error unless
mysqld is started by the
root
user.
You may be able to increase REPAIR
TABLE
performance by setting certain system
variables. See Section 10.6.3, “Optimizing REPAIR TABLE Statements”.
REPAIR TABLE
upgrades a table
if it contains old temporal columns in pre-5.6.4 format;
namely, the TIME
,
DATETIME
, and
TIMESTAMP
columns that lacked
support for fractional seconds precision.