This post explains on the usage of mysql_repair_threads for repairing myisam table & the processlist status Repair with N threads
The post corrupted / crashed MyISAM + mysql_repair_threads = stuck “Repair with N threads” first appeared on Change Is Inevitable.
MySQL is the most popular open-source database in the world. It
has the distinction of being the only database that is used in
every continent. Yes, even Antartica!!! The reasons for such
popularity is its availability, performance, robustness, etc. It
provides three types of database engines, MyISAM, InnoDB, and
MySQL Archive. Out of these, the MyISAM table is the default
table type. It is fast, simple, and allows full-text searching.
Although it is reliable, it can become corrupt and, thus,
inaccessible following a system crash. You should use appropriate
corrective measures to repair MySQL database. However, if you are
not able to do so then you should use a third-party MySQL
recovery software to do so.
Consider a scenario wherein you have MySQL 5.0.22 database
running in your system. You use it for MediaWiki installation
that is reported as corrupt. When you try to repair the table,
the following error message is displayed:
…
Any corruption in MyISAM table is a terrible situation for
Database Administrator. These MyISAM tables are the most
important components in the MySQL Database to store personal as
well as professional data, and the corruption in these tables may
inaccessibility to the database. In this situation, a database
backup allows you to restore the database and access the records
in the table. Duplicate file (Backup) of the database is mostly
stored on a different storage media, the changes of database
corruption still exist. In that situation, you will need to
perform MySQL database repair by the using of third party
software.
Some error messages that enable you to identify that your MyISAM
table (student) is corrupt:
“Student.frm is locked against change”
Or
“Got error message student from table handler”
Or
“Can't find file student.MYI (Errcode: nnn)”
The record …
It felt like the right time for us to look back at some useful commands for table maintenance that some of us may not have mastered as much as we might like to think.
In my post about gathering index statistics, I referred to
OPTIMIZE TABLE, ANALYZE TABLE, and
REPAIR TABLE — but I never explained in depth what
the different commands do, and what the differences between them
are. That is what I thought I would do with this post, focusing
on InnoDB and MyISAM, and the differences in how they treat those
commands. I will also look at different cases and see which one
is right for in each case.