Bug #24934 Log archiving in InnoDB unclear in Manual
Submitted: 9 Dec 2006 12:49 Modified: 14 Dec 2006 16:29
Reporter: Mikael Ronström Email Updates:
Status: Closed Impact on me:
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:5.0 OS:
Assigned to: MC Brown CPU Architecture:Any

[9 Dec 2006 12:49] Mikael Ronström
/* Start cut from section 14.2.3 */
A simple my.cnf  example. Suppose that you have a computer with 128MB RAM and one hard disk. The following example shows possible configuration parameters in my.cnf or my.ini for InnoDB, including the autoextend attribute. The example suits most users, both on Unix and Windows, who do not want to distribute InnoDB data files and log files onto several disks. It creates an auto-extending data file ibdata1 and two InnoDB log files ib_logfile0 and ib_logfile1 in the MySQL data directory. Also, the small archived InnoDB log file ib_arch_log_0000000000 that InnoDB creates automatically ends up in the data directory.
/* End cut */

/* Start cut from section 14.2.4 */

The directory where fully written log files would be archived if we used log archiving. If used, the value of this variable should be set the same as innodb_log_group_home_dir. However, it is not required.


Whether to log InnoDB archive files. This variable is present for historical reasons, but is unused. Recovery from a backup is done by MySQL using its own log files, so there is no need to archive InnoDB log files. The default for this variable is 0.

/* End cut */

From section 14.2.4 it appears that the archiving feature is not needed
anymore and also not active by default. Still it's mentioned in the chapter
14.2.3 which should state only the most important things. Looks very
suspicious to me.

Also the comment on innodb_log_arch_dir where it is stated "However, it is
not required" is unclear what it means. It says that if set it should be
set to the same as innodb_log_group_home_dir. But the question which is
unclear to me is whether it can be set to an arbitrary value. If it cannot
be set to this one wonders why it would not simply be set to true or false
dependent on whether it is datadir or log_group_home_dir

How to repeat:
See description
[9 Dec 2006 13:09] Valeriy Kravchuk
Thank you for a reasonable documentation request.
[11 Dec 2006 12:56] Heikki Tuuri

Please remove the mention of ib_arch_log_0000000000, because InnoDB has not created those files in the past 4 years.

Please also remove the mention of innodb_log_arch_dir altogether. That parameter has not been relevant in the past 4 years.


[14 Dec 2006 16:29] MC Brown
Thanks for the update. The documentation has been updated accordingly.