MySQL使用REPAIR TABLE 在MyISAM 表中报告”Table ‘X’ is Read Only” 错误

适用于:

MySQL 服务器版本4.0及以上

本文信息适用于所有平台。

 

症状

在修复一个MyISAM表时,”Table ‘x’ is read only”错误是什么意思,如何修复它?

 

mysql> repair table t;
+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐ ‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| Table | Op | Msg_type | Msg_text |
+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| test.t | repair | Error | Table 't' is read only |
| test.t | repair | status | Operation failed |
+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+

 

原因

这个错误有两个可能的起因:

  1. MyISAM文件MYD或MYI有错误权限且mysqld进程不能写它们
  2. MyISAM表被压缩

 

 

查看MyISAM表是否被压缩,运行

 

show table status like 't';

 

如果表被压缩,Row_format 显示 “Compressed”:

 

 

mysql> show table status like 't'\G


*************************** 1. row ***************************
Name: t
Engine: MyISAM
Version: 10
Row_format: Compressed <‐‐‐‐‐‐‐‐
Rows: 0
Avg_row_length: 0
Data_length: 41
Max_data_length: 281474976710655
Index_length: 1024
Data_free: 0
Auto_increment: NULL
Create_time: 2013‐0 6‐27 19:29:49
Update_time: 2013‐06‐27 19:29:49
Check_time: NULL
Collation: latin 1_swedish_ci
Checksum: 0
Create_options:
Comment:
1 row in s et (0.02 sec)

 

 

解决方案

对于每个可能的原因,(各个)解决方案有:

  1. MyISAM文件MYD或MYI有错误权限且mysqld进程不能写它们,要修复它,在shell上运行:

 

chgrp ‐R mysql <dataDir>
chown ‐R mysql <dataDir>
chmod ‐R 660 <dataDir>

 

  1. MyISAM表被压缩,要修复这个问题在shell运行:

 

myisamchk.exe ‐‐unpack <dataDir>\<db_name>\<table_name>

Then the table can be repaired:

mysql> flush tables;
Query OK, 0 rows affected (0.01 sec)

mysql> repair table t;

+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐ ‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐+
| Table | Op | Msg_type | Msg_text |
+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐ ‐‐‐‐+
| test.t | repair | status | OK |
+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐+
1 row in set (0.05 sec)

 

参考

https://dev.mysql.com/doc/en/repairtable.html

http://dev.mysql.com/doc/en/myisamchkrepairoptions.html#option_myisamchk_unpack

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