Changing the default value (3) of log_error_verbosity in MySQL/Percona Server for MySQL 5.7 can have a hidden unintended effect! What does log_error_verbosity do exactly? As per the documentation:
“The log_error_verbosity system variable specifies the verbosity for handling events intended for the error log.“
Basically a value of 1 logs only [Errors]; 2 is 1)+[Warnings]; and 3 is 2)+[Notes].
For example, one might be tempted to change the default of log_error_verbosity since the error.log might be bloated with thousands (or millions) of lines with [Notes], such as:
2020-10-08T17:02:56.736179Z 3 [Note] Access denied for user 'root'@'localhost' (using password: NO) 2020-10-08T17:04:48.149038Z 4 [Note] Aborted connection 4 to db: 'unconnected' user: 'root' host: 'localhost' (Got timeout reading communication packets)
(P.S. you can read more about those Notes on this other Percona blog posts):…[Read more]