MySQL Bugs: #88382: Persisted configuration in mysqld-auto.cnf is not reflected in mysqld output

Bug #88382	Persisted configuration in mysqld-auto.cnf is not reflected in mysqld output
Submitted:	7 Nov 2017 9:13	Modified:	7 Nov 2017 13:08
Reporter:	Oli Sennhauser	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: Options	Severity:	S3 (Non-critical)
Version:	8.0.3	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
Persisted configuration in mysqld-auto.cnf is not reflected in mysqld --help --verbose output

How to repeat:
SET PERSIST slow_query_log = ON;
--> Writes mysqld-auto.cnf

mysqld --help --verbose
Default options are read from the following files in the given order:
/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf /home/mysql/database/mysql-8.0/data/my.cnf ~/.my.cnf 

Does not show, that mysqld-auto is read during start. Which SHOULD IMHO.

Suggested fix:
add $datadir/mysqld-auto.cnf to mysqld --help --verbose output!

Hello Oli,

Thank you for the report and feedback!

Thanks,
Umesh

Posted by developer:
 
It can't really source mysqld-auto.cnf at --help time. Unlike the other config files, this one can contain values for variables that are to be set at runtime. And processing it is much more complicated compared to the other config files. Please use https://dev.mysql.com/doc/refman/9.4/en/performance-schema-persisted-variables-table.html table to read these values. 

Converting to a docs bug so this is properly documented.