I'd hope one of the first things for DB slow down is the running queries (eg. `show processlist` in flavors of MySQL) and seeing the number of rows examined. Ma

I'd hope one of the first things for DB slow down is the running queries (eg. `show processlist` in flavors of MySQL) and seeing the number of rows examined. Maybe your DB doesn't have that, so you see hopefully see long running queries and they are mostly the same one, or you can see the same queries in your DB's engine status (eg. `show innodb status` in MySQL). If you don't have rows examined from earlier, you can run whatever equivalent you have of `explain` on these long running queries that are happening a lot, and now you should find the number of rows it is examining (and probably that it is running a scan query and not indexed). I mean, you only get these scars from actually working with your DB and hopefully in development / capacity planning stages, so maybe that makes you a rockstar. Not to take anything away from the Stripe engineer(s).