RDS cheatsheet

Referenced from : https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_Limits.html#RDS_Limits.MaxConnections

Maximum Concurrent Connections

Aurora

Instance	Max Connections
db.t2.small	45
db.t2.medium	90
db.t3.small	45
db.t3.medium	90
db.r3.large	1000
db.r3.xlarge	2000
db.r3.2xlarge	3000
db.r3.4xlarge	4000
db.r3.8xlarge	5000
db.r4.large	1000
db.r4.xlarge	2000
db.r4.2xlarge	3000
db.r4.4xlarge	4000
db.r4.8xlarge	5000
db.r4.16xlarge	6000

MariaDB and MySQL

RDS MariaDB and MySQL max connections are constrained by the formula:

Instance Memory / 12582880

Instance	vCPUs	Memory (GB)	Max Connections
db.t2.micro	1	1	85
db.t2.small	1	2	171
db.t2.medium	2	4	341
db.t2.large	2	8	683
db.t2.xlarge	4	16	1365
db.t2.2xlarge	8	32	2731
db.t3.micro	2	1	85
db.t3.small	2	2	171
db.t3.medium	2	4	341
db.t3.large	2	8	683
db.t3.xlarge	4	16	1365
db.t3.2xlarge	8	32	2731
db.r4.large	2	15.25	1301
db.r4.xlarge	4	30.5	2603
db.r4.2xlarge	8	61	5205
db.r4.4xlarge	16	122	10411
db.r4.8xlarge	32	244	20821
db.r4.16xlarge	64	488	41643

PostgreSQL

RDS PostgreSQL max connections are constrained by the formula:

LEAST({DBInstanceClassMemory/9531392}, 5000)

Instance	vCPUs	Memory (GB)	Max Connections
db.t2.micro	1	1	112
db.t2.small	1	2	225
db.t2.medium	2	4	450
db.t2.large	2	8	901
db.t2.xlarge	4	16	1802
db.t2.2xlarge	8	32	3604
db.t3.micro	2	1	112
db.t3.small	2	2	225
db.t3.medium	2	4	450
db.t3.large	2	8	901
db.t3.xlarge	4	16	1802
db.t3.2xlarge	8	32	3604
db.r4.large	2	15.25	1717
db.r4.xlarge	4	30.5	3435
db.r4.2xlarge	8	61	5000
db.r4.4xlarge	16	122	5000
db.r4.8xlarge	32	244	5000
db.r4.16xlarge	64	488	5000