1GB = 1,07,37,41,824 字节(1024 x 1024 x1024)

{DBInstanceClassMemory/12582880} = 默认的最大连接数

通过连接数据库，运行

show variables like '%max_connections%';

实际得出的 max_connections < {DBInstanceClassMemory/12582880}

由于为操作系统和 RDS 管理进程预留了内存

Name	API Name	Memory GIB	vCPUs	max_connections
T3 Micro	db.t3.micro	1 GiB	2 vCPUs	85
T2 General Purpose Micro	db.t2.micro	1 GiB	1 vCPUs	85
CV11 Small	db.cv11.small	1 GiB	1 vCPUs	85
M1 General Purpose Small	db.m1.small	1.7 GiB	1 vCPUs	145
T3 Small	db.t3.small	2 GiB	2 vCPUs	170
T2 General Purpose Small	db.t2.small	2 GiB	1 vCPUs	170
CV11 Medium	db.cv11.medium	2 GiB	1 vCPUs	170
M3 General Purpose Medium	db.m3.medium	3.75 GiB	1 vCPUs	320
M1 General Purpose Medium	db.m1.medium	3.75 GiB	1 vCPUs	320
T3 Medium	db.t3.medium	4 GiB	2 vCPUs	341
T2 General Purpose Medium	db.t2.medium	4 GiB	2 vCPUs	341
MV11 Medium	db.mv11.medium	4 GiB	1 vCPUs	341
CV11 Large	db.cv11.large	4 GiB	2 vCPUs	341
M3 General Purpose Large	db.m3.large	7.5 GiB	2 vCPUs	640
M1 General Purpose Large	db.m1.large	7.5 GiB	2 vCPUs	640
T3 Large	db.t3.large	8 GiB	2 vCPUs	682
T2 General Purpose Large	db.t2.large	8 GiB	2 vCPUs	682
MV11 Large	db.mv11.large	8 GiB	2 vCPUs	682
M5 Large	db.m5.large	8 GiB	2 vCPUs	682
M4 General Purpose Large	db.m4.large	8 GiB	2 vCPUs	682
CV11 Extra Large	db.cv11.xlarge	8 GiB	4 vCPUs	682
M3 General Purpose Extra Large	db.m3.xlarge	15 GiB	4 vCPUs	1280
M1 General Purpose Extra Large	db.m1.xlarge	15 GiB	4 vCPUs	1280
R4 Memory Optimized Large	db.r4.large	15.25 GiB	2 vCPUs	1301
R3 Memory Optimized Large	db.r3.large	15.25 GiB	2 vCPUs	1301
Z1D Large	db.z1d.large	16 GiB	2 vCPUs	1365
T3 Extra Large	db.t3.xlarge	16 GiB	4 vCPUs	1365
T2 General Purpose Extra Large	db.t2.xlarge	16 GiB	4 vCPUs	1365
RV11 Large	db.rv11.large	16 GiB	2 vCPUs	1365
R5 Large	db.r5.large	16 GiB	2 vCPUs	1365
MV11 Extra Large	db.mv11.xlarge	16 GiB	4 vCPUs	1365
M5 Extra Large	db.m5.xlarge	16 GiB	4 vCPUs	1365
M4 General Purpose Extra Large	db.m4.xlarge	16 GiB	4 vCPUs	1365
CV11 Double Extra Large	db.cv11.2xlarge	16 GiB	8 vCPUs	1365
M2 High Memory Extra Large	db.m2.xlarge	17.1 GiB	2 vCPUs	1459
M3 General Purpose Double Extra Large	db.m3.2xlarge	30 GiB	8 vCPUs	2560
R4 Memory Optimized Extra Large	db.r4.xlarge	30.5 GiB	4 vCPUs	2602
R3 Memory Optimized Extra Large	db.r3.xlarge	30.5 GiB	4 vCPUs	2602
Z1D Extra Large	db.z1d.xlarge	32 GiB	4 vCPUs	2730
T3 Double Extra Large	db.t3.2xlarge	32 GiB	8 vCPUs	2730
T2 General Purpose Double Extra Large	db.t2.2xlarge	32 GiB	8 vCPUs	2730
RV11 Extra Large	db.rv11.xlarge	32 GiB	4 vCPUs	2730
R5 Extra Large	db.r5.xlarge	32 GiB	4 vCPUs	2730
MV11 Double Extra Large	db.mv11.2xlarge	32 GiB	8 vCPUs	2730
M5 Double Extra Large	db.m5.2xlarge	32 GiB	8 vCPUs	2730
M4 General Purpose Double Extra Large	db.m4.2xlarge	32 GiB	8 vCPUs	2730
CV11 Quadruple Extra Large	db.cv11.4xlarge	32 GiB	16 vCPUs	2730
M2 High Memory Double Extra Large	db.m2.2xlarge	34.2 GiB	4 vCPUs	2918
R4 Memory Optimized Double Extra Large	db.r4.2xlarge	61 GiB	8 vCPUs	5205
R3 Memory Optimized Double Extra Large	db.r3.2xlarge	61 GiB	8 vCPUs	5205
Z1D Double Extra Large	db.z1d.2xlarge	64 GiB	8 vCPUs	5461
RV11 Double Extra Large	db.rv11.2xlarge	64 GiB	8 vCPUs	5461
R5 Double Extra Large	db.r5.2xlarge	64 GiB	8 vCPUs	5461
MV11 Quadruple Extra Large	db.mv11.4xlarge	64 GiB	16 vCPUs	5461
M5 Quadruple Extra Large	db.m5.4xlarge	64 GiB	16 vCPUs	5461
M4 General Purpose Quadruple Extra Large	db.m4.4xlarge	64 GiB	16 vCPUs	5461
M2 High Memory Quadruple Extra Large	db.m2.4xlarge	68.4 GiB	8 vCPUs	5836
CV11 9xlarge	db.cv11.9xlarge	72 GiB	36 vCPUs	6144
Z1D 3xlarge	db.z1d.3xlarge	96 GiB	12 vCPUs	8192
X1E Extra Large	db.x1e.xlarge	122 GiB	4 vCPUs	10410
R4 Memory Optimized Quadruple Extra Large	db.r4.4xlarge	122 GiB	16 vCPUs	10410
R3 Memory Optimized Quadruple Extra Large	db.r3.4xlarge	122 GiB	16 vCPUs	10410
RV11 Quadruple Extra Large	db.rv11.4xlarge	128 GiB	16 vCPUs	10922
R5 Quadruple Extra Large	db.r5.4xlarge	128 GiB	16 vCPUs	10922
M5 Eight Extra Large	db.m5.8xlarge	128 GiB	32 vCPUs	10922
CV11 18xlarge	db.cv11.18xlarge	144 GiB	72 vCPUs	12288
M4 General Purpose Deca Extra Large	db.m4.10xlarge	160 GiB	40 vCPUs	13653
Z1D 6xlarge	db.z1d.6xlarge	192 GiB	24 vCPUs	16384
MV11 12xlarge	db.mv11.12xlarge	192 GiB	48 vCPUs	16384
M5 12xlarge	db.m5.12xlarge	192 GiB	48 vCPUs	16384
X1E Double Extra Large	db.x1e.2xlarge	244 GiB	8 vCPUs	20821
R4 Memory Optimized Eight Extra Large	db.r4.8xlarge	244 GiB	32 vCPUs	20821
R3 Memory Optimized Eight Extra Large	db.r3.8xlarge	244 GiB	32 vCPUs	20821
R5 Eight Extra Large	db.r5.8xlarge	256 GiB	32 vCPUs	21845
M5 16xlarge	db.m5.16xlarge	256 GiB	64 vCPUs	21845
M4 General Purpose 16xlarge	db.m4.16xlarge	256 GiB	64 vCPUs	21845
Z1D 12xlarge	db.z1d.12xlarge	384 GiB	48 vCPUs	32768
RV11 12xlarge	db.rv11.12xlarge	384 GiB	48 vCPUs	32768
R5 12xlarge	db.r5.12xlarge	384 GiB	48 vCPUs	32768
MV11 24xlarge	db.mv11.24xlarge	384 GiB	96 vCPUs	32768
M5 24xlarge	db.m5.24xlarge	384 GiB	96 vCPUs	32768
X1E Quadruple Extra Large	db.x1e.4xlarge	488 GiB	16 vCPUs	41642
R4 Memory Optimized 16xlarge	db.r4.16xlarge	488 GiB	64 vCPUs	41642
R5 16xlarge	db.r5.16xlarge	512 GiB	64 vCPUs	43690
RV11 24xlarge	db.rv11.24xlarge	768 GiB	96 vCPUs	65536
R5 24xlarge	db.r5.24xlarge	768 GiB	96 vCPUs	65536
X1E Eight Extra Large	db.x1e.8xlarge	976 GiB	32 vCPUs	83285
X1 16xlarge	db.x1.16xlarge	976 GiB	64 vCPUs	83285
X1E 16xlarge	db.x1e.16xlarge	1952 GiB	64 vCPUs	166571
X1 32xlarge	db.x1.32xlarge	1952 GiB	128 vCPUs	166571
X1E 32xlarge	db.x1e.32xlarge	3904 GiB	128 vCPUs	333142