Bug #57974 Performance_Schema DB name
Submitted: 4 Nov 2010 11:44 Modified: 4 Nov 2010 15:27
Reporter: Peter Laursen (Basic Quality Contributor) Email Updates:
Status: Not a Bug Impact on me:
None 
Category:MySQL Server: Performance Schema Severity:S3 (Non-critical)
Version:5.5.3+ OS:Any
Assigned to: Marc ALFF CPU Architecture:Any
Tags: qc

[4 Nov 2010 11:44] Peter Laursen
Description:
This reports both the server, mysqldump, docs for both and 3rd party programs as well.  I am setting as a server issue as I believe the most 'elegant' fix would be in the server. Maybe also you will find this report a little 'exotic' too - but I do not think it is completely irrelevant.

The report is also an assumption / a hypothesis only.  I do not have option to build the server with special configure options.

The problem:

'mysqldump' as of 5.5 does not backup Performance_Schema with --all-databases.  This is correct and similar to how Information_Schema was handled from 5.0.

Problem is however that Performance_Schema is an optional database. 
http://dev.mysql.com/doc/refman/5.5/en/configure-options.html
.. lists "--with-perfschema" as a configure parameter

If user builds and configures without "--with-perfschema" will he then be able to create his own Performance_Schema database? If so the problem is that "mysqldump --all-databases" will not include it.

How to repeat:
see above

Suggested fix:
I think best option is to make "Performance-Schema" (all LETERCASE variants) an invalid name for a user database.

My apology if this is already considered and/or documented (as proposed here or some other way), but I was not able to find any information about this possible conflict.
[4 Nov 2010 15:26] Marc ALFF
Thanks for the report.

The following statement from the description:

"
Problem is however that Performance_Schema is an optional database. 
http://dev.mysql.com/doc/refman/5.5/en/configure-options.html
.. lists "--with-perfschema" as a configure parameter
"

is incorrect.

The performance schema *feature* is optional in mysql 5.5 and can be compiled conditionally depending on configure options.

The "performance_schema" *database* is *not* optional in mysql 5.5, and this database is always created by the install / upgrade scripts in 5.5, even when the performance schema feature is not available.

This is done precisely to reserve the name of the "performance_schema" database for the server implementation.

Closing this report as not a bug.
[4 Nov 2010 15:27] Peter Laursen
fine then.  and thanks!