[wreath]

You can change the max_connections in RDS though. The default is insanely high and I have no idea what it is that way. 4vCPU instances running with 5k max connections iirc, I have never seen an instance this size handle more than 100-200 concurrent connections on a CPU bound workload.

[darkwater]

There is still a max capped on the instance size [1] (well, RAM available) although now that I'm checking it again I swear it was different last time I read it. Anyway I did totally had issues with big replicated monoliths with their own connection pool (i.e. old Rails) maxing out connections on RDS.

[1] https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_...