MySQL Bugs: #46536: MEM Manual section on "Creating a Custom Data Collection Item" needs updating

Bug #46536	MEM Manual section on "Creating a Custom Data Collection Item" needs updating
Submitted:	3 Aug 2009 23:24	Modified:	11 Aug 2009 14:43
Reporter:	Andy Bang	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Enterprise Monitor: Documentation	Severity:	S3 (Non-critical)
Version:	2.1.0.1080	OS:	Any
Assigned to:	MC Brown	CPU Architecture:	Any

Description:
Section "7.4.8. Creating a Custom Data Collection Item" in the MEM Manual needs to be updated.

In 2.1 we created a new file, custom.xml, as a placeholder for customers to put custom SQL data collection definitions.  During a new agent install, this file will be created and referenced in the "agent-item-files parameter" (incorrectly called "item-files" in the current docs) in the mysql-monitor-agent.ini file.  During an upgrade installation, this file will be preserved as is, whereas other files may be changed or deleted.  Thus customers are urged to use this file for the custom DC definitions.

In addition, note that the custom.xml file is listed last on the "agent-item-files" parameter, which means it will be read last.  Thus if a customer wants to override one of the custom SQL definitions we provide, they can duplicate it in custom.xml and make their changes there, and it will overwrite what we provide because it read last.  See Bug #45755.  This should be mentioned in the manual.

Why change one of ours?  If you change the name of the root account and don't want to trigger other rules that expect the root account to be named "root" (see Bug #46023).  It would be great to mention this in the manual, too.

How to repeat:
See Description.

Martin MC Brown writes: 
I've rewritten this section for 2.1 to note that the custom.xml file should be used. 

I've also separately made a note that parts of this need to be updated, which will be done as part of the custom graphs work