Hello,
I understand that you would like to know why your MySQL instance was down. I can see that you have configured 4030 max_connections for your instance. Please note that there is a Maximum Concurrent connection limit of 4000[1] for all other machine types of the Cloud SQL 2nd Generation. However you are using a "db-g1-small" type which has 1000 max_connections limit. The documentation clearly shows that the Maximum Concurrent connection limit is a fixed limit. So, there is no possibility to request a Quota increase or change this value.
As a solution, you can choose any Machine Type [2] other than "db-g1-small" or "db-f1-micro" which will allow you 4000 maximum connections limit.
I have also created a feature request in Public Issue Tracker [3] on your behalf to support more than 4000 maximum connections. You can track the Public Issue Tracker for the updates. Please note that there is no timeline or implementation guarantee for feature requests
Also by checking the screenshots provided, I was able to see that you are not reaching to 1000 active connections. So maybe your MySQL instance went down to any other issue, could you please check Cloud Logging for your instance to see errors? Please share the errors with me.
An another possibility could be that you had a maintenance update to which your instance went down for few minutes. Maintenance updates take the Cloud SQL instance down to fix bugs, prevent security exploits, and perform upgrades [4]. You can check if this was your case going to your instance --> Clicking on Operations and check if you had an update operation at the timestamp when your SQL instance was down.
Looking forward to your reply.
Best Regards,
Nibrass
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