Disable Debug Log Programmatically

I’m trying to disable WP_DEBUG_LOG if and only if debug.log exists. I’d like to hook into wp_footer and test if the file exists and if so disable my debug log. All I’ve found though is that WP_DEBUG_LOG is a constant and can only be changed from the wp-config.php file which is too early for my case. Is there a way to change it from a constant on install and keep it working as normal?

How to monitor server for error establishing a database connection

I know there are tools like pingdom.com and uptimerobot.com that will monitor your site and let you know if they’re down, but I find that my WordPress site is experiencing the dreaded “error establishing a database connection” more often than desired, and I’d like to get some sort of notification when that happens (but not in the form of a user complaint!). Pingdom and Uptimerobot do not consider that an error, and thus do not push any notifications.