Bug #61539 Warning if innodb_rollback_segments is different from 128 during startup
Submitted: 16 Jun 2011 15:52 Modified: 20 Jun 2011 13:15
Reporter: Arnaud Adant Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: InnoDB storage engine Severity:S4 (Feature request)
Version:5.5 OS:Any
Assigned to: CPU Architecture:Any

[16 Jun 2011 15:52] Arnaud Adant 
Description:
During the binary upgrade from 5.1 to 5.5, if the user did not perform a slow shutdown, it will miss the new multi-rollback segment feature.

How to repeat:
Start MySQL 5.5.13 server, there is no warning if the innodb_rollback_segments <> 128, which means that a slow shutdown was not performed after a binary upgrade.

Suggested fix:
1. Print the variable at startup in the error log.

2. Add a warning at startup in the error log if the slow shutdown was not performed after the binary upgrade.
[20 Jun 2011 13:14] Arnaud Adant 
Other possible fix :

3. show the number of active rollback segments in the information_schema

4. show the number of active rollback segments in show engine innodb status
[20 Jun 2011 15:48] Simon Mudd 
You make 2 suggestions:

3. show the number of active rollback segments in the information_schema

This seems like a good idea, and should probably go in SHOW GLOBAL VARIABLES output, or I_S.GLOBAL_VARIABLES.

4. show the number of active rollback segments in show engine innodb status

I'd prefer the information were not kept here. IIRC the size of the output is limited and if a lot of data is shown may get truncated. Apart from that parsing the output from SQL is next to impossible.
[20 Jun 2011 15:53] Simon Mudd 
Note: as there is a GLOBAL VARIABLES setting already and it seems this might be 
different to the running config use the GLOBAL STATUS values, and I_S.GLOBAL_STATUS.