MySQL 5.7Error log parameter log_error_verbosity

When checking the error log, it is found that there is a large amount of [Note] Multi-threaded slave statistics for channel output, and the error log is already very large. Although it is note, it still looks uncomfortable, so just turn it off. The current version is 5.7.17, so the corresponding parameter is found to be log-error-verbosity, which is a dynamic parameter from the official documentation, so it can be modified online. Set GLOBAL log_error_verbosity=2; directly and after modification, the Note will not continue to appear in the error log. Now let's learn why it should be changed to 2. In MySQL, where log_error defines whether the error log is enabled and where the error log is stored, and log_warnings defines whether the alarm information (warning messages) is also written to the error log. There are different options in different versions, as described in MySQL 5.6.This option is enabled by default as follows: if log_warnings is 0, alarm information is not recorded. Log_warnings is 1, which means that the alarm information is written to the error log. Log_warnings is greater than 1, indicating that all kinds of alarm information, such as information about network failure and reconnection, are written to the error log. Starting with MySQL 5.7.2, the log_error_verbosity system variable is used instead of the-log-warnings option or the log_warnings system variable, but this parameter is removed from MySQL 8.0.3. In MySQL 5.7, some defaults are 2, some are 1, and my 5.7.17 is 3. In MySQL 5.7, this is a new parameter, and log_error_verbosity is simpler. It has three optional values: 1: error message; 2: error message and alarm message; 3: error message, alarm message, and notification message.