MySQL Bugs: #68962: Inaccurate description of innodb_undo

Bug #68962	Inaccurate description of innodb_undo_tablespaces in the manual
Submitted:	15 Apr 2013 12:23	Modified:	22 Apr 2013 17:54
Reporter:	Alexey Kopytov	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S3 (Non-critical)
Version:		OS:	Any
Assigned to:	Bugs System	CPU Architecture:	Any

Description:
http://dev.mysql.com/doc/refman/5.6/en/innodb-parameters.html#sysvar_innodb_undo_tablespac... provides the following description for innodb_undo_tablespaces:

"
Version Introduced	5.6.3
Command-Line Format	--innodb_undo_tablespaces=#
Option-File Format	innodb_undo_tablespaces
Option Sets Variable	Yes, innodb_undo_tablespaces
Variable Name	innodb_undo_tablespaces
Variable Scope	Global
Dynamic Variable	Yes
 	Permitted Values
Type	numeric
Default	126
Min Value	0

The number of tablespace files that the undo logs are divided between, when you use a non-zero innodb_undo_logs setting. By default, all the undo logs are part of the system tablespace. Because the undo logs can become large during long-running transactions, splitting the undo logs between multiple tablespaces reduces the maximum size of any one tablespace. The tablespace files are created in the location defined by innodb_undo_directory, with names of the form innodbN, where N is a sequential series of integers, including leading zeros."

Issues:

1. It is not a dynamic variable.
2. The default value is 0 (but the maximum one is indeed 126).
3. The names for undo tablespaces is of the form "undoN", rather than "innodbN".

How to repeat:
Compare innodb_undo_tablespaces declaration in ha_innodb.cc and the initialization code in srv_undo_tablespaces_init() with the manual.

Hello Alexey,

Thank you for the report.
Verified as described.

Thanks,
Umesh

Thank you for your bug report. This issue has been addressed in the documentation. The updated documentation will appear on our website shortly, and will be included in the next release of the relevant products.