We have recently upgraded from MySQL 5.7 to 8.0 on AWS RDS. Due to lack of knowledge we have gone for the default parameter group.
Two main results so far:
Firstly, the read replica seems to lose FreeStorageSpace. Under 5.7, both the master and the replica used to have identical graphs on CloudWatch. Now the read replica line drops quickly away from the master. In our instance the read replica is of smaller size than the master, but this has never been an issue.
Secondly (and less importantly), Performance Insights doesnt seem to work. When clicking on it, it just shows "No Active sessions in selected time range". Have removed and readded it, but makes no difference.
Does anyone have a few recommended changes to the default parameter group and/or any ideas what might be causing the two issues above?
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_PerfInsights.html
"Amazon RDS Performance Insights is not supported for MariaDB version 10.0, 10.1, or 10.3, or for MySQL version 5.5 or 8.0."