[throwdbaaway]

https://status.slack.com/2022-02-22 has been updated with this:

> A configuration change inadvertently lead to a sudden increase in activity on our database infrastructure. Due to this increased activity, the affected databases failed to serve incoming requests to connect to Slack. We introduced tighter rate limits on connection requests to reduce the load on the system. This meant that some people could not access Slack at all, but also that Slack would continue working for those who were already connected.

> Once the system had stabilized, we began lifting these rate limits to enable more connections to Slack. However, we moved too quickly and the increased activity affected the system again. We reinstated the rate limits and redirected some traffic to the database replicas to relieve the demand on our primary databases.

I wonder if their bottleneck is at vitess vttablet or at mysql.