Track slow queries on MySQL

A threshold of 1 second is a reasonable starting point, tune it down once you've cleared the obvious offenders.

SET GLOBAL slow_query_log = 'ON';
SET GLOBAL long_query_time = 1;
SET GLOBAL log_output = 'TABLE';

GLOBAL variables reset on restart unless they're also set in the config file.

# my.cnf
[mysqld]
slow_query_log = 1
long_query_time = 1
log_output = TABLE

The database's Overview tab lists the slowest queries in the current window, with average duration and call count, so you can prioritize by actual impact rather than guesswork.

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