AWS RDS Max Connections Limit As Per Instance Type

In this article, we’ll explain AWS RDS Max Connections Limit as per Instance Type. Amazon Web Services (AWS) offers a range of cloud-based services, including the Amazon Relational Database Service (RDS), which provides a fully-managed database service for applications. One of the critical considerations when using RDS is the maximum number of connections allowed for a database instance. In this article, we will explore the concept of maximum connections, the factors that affect it, and how to manage it in AWS RDS.

What is the maximum connections limit in AWS RDS?

The maximum connections limit refers to the maximum number of concurrent database connections that can be established to an RDS instance. It is a fundamental parameter that affects the performance, availability, and scalability of the database. The maximum connection limit varies depending on the RDS instance class and the database engine used.

However, reaching the maximum connection limit does not necessarily mean that the database will perform well. Too many active connections can lead to contention and poor performance. It is essential to monitor the database performance and tune the settings accordingly.

How to manage the maximum connections limit in AWS RDS

Managing the maximum connections limit is critical to ensure the performance and availability of the database. AWS RDS provides several options to manage the maximum connections limit.

Monitoring

It is essential to monitor the maximum connections limit regularly to ensure that the database is not reaching its limit. Amazon CloudWatch provides metrics to monitor the maximum connections limit. You can create an alarm that triggers when the maximum connections limit is close to being reached.

Modifying the maximum connections limit

If you need to increase or decrease the maximum connections limit, you can modify the database parameter group associated with the RDS instance. The database parameter group contains database engine configuration options, including the maximum connections limit. You can modify the maximum connections limit parameter and apply the changes to the database instance.

Connection pooling

Connection pooling can help manage the maximum connections limit by reducing the number of connections required by the application. Connection pooling allows the application to reuse existing connections instead of creating new connections for every request.

Load balancing

Load balancing can help manage the maximum connections limit by distributing the incoming connections across multiple database instances. AWS RDS supports load balancing through Amazon RDS Proxy, which provides a highly available and scalable database proxy for applications to connect to RDS instances. Amazon RDS Proxy can help manage the maximum connections limit by distributing the incoming connections across multiple database instances.

Query optimization

Query optimization can help manage the maximum connections limit by reducing the time required for each query. Optimized queries can reduce the number of active connections required by the application, allowing the database to handle more concurrent connections.

Scaling the RDS instance

If you reach the maximum connections limit frequently, it may be time to consider scaling up the RDS instance. Scaling up the instance class can increase the maximum connections limit and provide more resources to the database. AWS RDS also supports scaling out through read replicas, which can help manage the maximum connections limit by distributing the read workload across multiple database instances.

RDS Max-DB Connection Limits as per DB Instance Type

Do and don’t and along with common mistakes:

Here are some do’s and don’ts, along with common mistakes, when working with AWS RDS Max Connections Limit:

Do’s:

1. Monitor Regularly: Monitor the maximum connections limit regularly to ensure it is not reaching its maximum capacity. Use Amazon CloudWatch to set up alarms when the limit is close to being reached.

2. Plan for Scalability: Consider the future scalability of your application and choose an appropriate RDS instance type with enough maximum connections to handle your expected growth.

3. Use Connection Pooling: Implement connection pooling in your application to reuse existing connections instead of creating new connections for each request. This can help manage the number of connections required and improve performance.

4. Optimize Queries: Optimize your database queries to reduce the time required for each query. Efficient queries can lead to fewer active connections, allowing the database to handle more concurrent connections.

5. Consider Load Balancing: If your application requires a high number of connections, consider using load balancing to distribute incoming connections across multiple RDS instances. Amazon RDS Proxy can be helpful in this regard.

6. Scale Up or Out: If you frequently reach the maximum connections limit, consider scaling up your RDS instance to a larger instance class or scaling out by using read replicas to distribute the workload.

Don’ts:

1. Ignore Monitoring: Ignoring monitoring of the maximum connection limit can lead to unexpected bottlenecks and performance issues.

2. Modify Default Parameter Groups: Avoid modifying values in the default DB parameter group, as you can’t change parameter values in it. Instead, create a custom DB parameter group for modifications.

3. Rely on Unlimited Connections: For SQL Server, be cautious when setting the maximum number of concurrent connections to 0 (unlimited). It may lead to excessive resource usage and performance degradation if not managed properly.

Common Mistakes:

1. Not Setting Appropriate Max Connections: Not setting an appropriate maximum connection limit for your RDS instance can lead to connection errors or poor performance when the application reaches the limit.

2. Using Default Parameter Groups: Modifying values in the default parameter group can result in errors and make it difficult to manage RDS instances effectively.

3. Overlooking Connection Pooling: Not implementing connection pooling can lead to an excessive number of connections being opened and closed, impacting the overall database performance.

4. Not Scaling as Needed: Failing to scale up or out when needed can cause performance bottlenecks and limit your application’s ability to handle increased traffic.

5. Neglecting Query Optimization: Ignoring query optimization can lead to poorly performing queries and increased resource usage, potentially reaching the maximum connections limit faster.

By following these do’s and avoiding the don’ts and common mistakes, you can effectively manage the AWS RDS Max Connections Limit and ensure optimal performance and availability of your database instance.

What is Max DB Connection?

Determines the maximum number of concurrent connections to the database server. This chart shows the max_connections limit, set by AWS, at various MySQL RDS instance sizes.

AWS sets the MySQL max connections system varies according to the size of the RDS instance. max connections are the maximum permitted number of simultaneous or concurrent client connections.  A “Too many connections” error message may be displayed if this is reached.

If an application implements long-running queries or creates several concurrent connections from the web or app side, the number of connections is just as important as vCPU cores, memory level, or storage IO.

for more info, see the MySQL max_connections sys variable, or AWS’s post regarding DB parameter groups.

AWS RDS Max Connections Limit

In this article, we’re going to explain MySQL RDS Max DB Connection Limits as per DB Instance Type. The current RDS MySQL max_connections setting is default by {DBInstanceClassMemory/12582880}, if you use t2.micro with 1GB RAM the max_connections could be (1024*1024*1024)/12582880 ~= 85.

A solution to “ERROR 1040 (08004): Too many connections”

How AWS RDS Max Connections calculated?

You need to convert memory from GB to bytes. So, you will get the DBInstanceClassMemory value and then you divide it by 12582880.

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

Maximum Database Connections Chart

DB Engine	Parameter	Allowed Values	Default Value
MariaDB and MySQL	max_connections	1–100000	{DBInstanceClassMemory/12582880}
Oracle	processes	80–20000	LEAST({DBInstanceClassMemory/9868951}, 20000)
	sessions	100–65535	–
PostgreSQL	max_connections	6–8388607	LEAST({DBInstanceClassMemory/9531392}, 5000)
SQL Server	Maximum number of concurrent connections	0–32767	0 (unlimited)

This chart shows the AWS RDS Max Connections Limit set by AWS at various RDS instance sizes.

AWS RDS Max Connections Limit as per Instance Type

RDS MySQL max_connections chart

Name	API Name	Memory GIB	vCPUs	max_connections
T1 Micro	db.t1.micro	0.613 GiB	1 vCPUs	52
T2 General Purpose Micro	db.t2.micro	1 GiB	1 vCPUs	85
T3 Micro	db.t3.micro	1 GiB	2 vCPUs	85
T4G Micro	db.t4g.micro	1 GiB	2 vCPUs	85
M1 General Purpose Small	db.m1.small	1.7 GiB	1 vCPUs	145
T2 General Purpose Small	db.t2.small	2 GiB	1 vCPUs	171
T3 Small	db.t3.small	2 GiB	2 vCPUs	171
T4G Small	db.t4g.small	2 GiB	2 vCPUs	171
M1 General Purpose Medium	db.m1.medium	3.75 GiB	1 vCPUs	320
M3 General Purpose Medium	db.m3.medium	3.75 GiB	1 vCPUs	320
T2 General Purpose Medium	db.t2.medium	4 GiB	2 vCPUs	341
T3 Medium	db.t3.medium	4 GiB	2 vCPUs	341
T4G Medium	db.t4g.medium	4 GiB	2 vCPUs	341
M1 General Purpose Large	db.m1.large	7.5 GiB	2 vCPUs	640
M3 General Purpose Large	db.m3.large	7.5 GiB	2 vCPUs	640
M4 General Purpose Large	db.m4.large	8 GiB	2 vCPUs	683
M5 Large	db.m5.large	8 GiB	2 vCPUs	683
M5D Large	db.m5d.large	8 GiB	2 vCPUs	683
M6G Large	db.m6g.large	8 GiB	2 vCPUs	683
M6GD Large	db.m6gd.large	8 GiB	2 vCPUs	683
M6I Large	db.m6i.large	8 GiB	2 vCPUs	683
T2 General Purpose Large	db.t2.large	8 GiB	2 vCPUs	683
T3 Large	db.t3.large	8 GiB	2 vCPUs	683
T4G Large	db.t4g.large	8 GiB	2 vCPUs	683
M1 General Purpose Extra Large	db.m1.xlarge	15 GiB	4 vCPUs	1280
M3 General Purpose Extra Large	db.m3.xlarge	15 GiB	4 vCPUs	1280
R3 Memory Optimized Large	db.r3.large	15.25 GiB	2 vCPUs	1301
R4 Memory Optimized Large	db.r4.large	15.25 GiB	2 vCPUs	1301
R5 Large	db.r5.large	16 GiB	2 vCPUs	1365
R5B Large	db.r5b.large	16 GiB	2 vCPUs	1365
R5D Large	db.r5d.large	16 GiB	2 vCPUs	1365
R6G Large	db.r6g.large	16 GiB	2 vCPUs	1365
R6GD Large	db.r6gd.large	16 GiB	2 vCPUs	1365
R6I Large	db.r6i.large	16 GiB	2 vCPUs	1365
Z1D Large	db.z1d.large	16 GiB	2 vCPUs	1365
M4 General Purpose Extra Large	db.m4.xlarge	16 GiB	4 vCPUs	1365
M5 Extra Large	db.m5.xlarge	16 GiB	4 vCPUs	1365
M5D Extra Large	db.m5d.xlarge	16 GiB	4 vCPUs	1365
M6G Extra Large	db.m6g.xlarge	16 GiB	4 vCPUs	1365
M6GD Extra Large	db.m6gd.xlarge	16 GiB	4 vCPUs	1365
M6I Extra Large	db.m6i.xlarge	16 GiB	4 vCPUs	1365
T2 General Purpose Extra Large	db.t2.xlarge	16 GiB	4 vCPUs	1365
T3 Extra Large	db.t3.xlarge	16 GiB	4 vCPUs	1365
T4G Extra Large	db.t4g.xlarge	16 GiB	4 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
R3 Memory Optimized Extra Large	db.r3.xlarge	30.5 GiB	4 vCPUs	2603
R4 Memory Optimized Extra Large	db.r4.xlarge	30.5 GiB	4 vCPUs	2603
R5 Large	db.r5.large.tpc1.mem2x	32 GiB	2 vCPUs	2731
R5B Large	db.r5b.large.tpc1.mem2x	32 GiB	2 vCPUs	2731
X2G Large	db.x2g.large	32 GiB	2 vCPUs	2731
R5 Extra Large	db.r5.xlarge	32 GiB	4 vCPUs	2731
R5B Extra Large	db.r5b.xlarge	32 GiB	4 vCPUs	2731
R5D Extra Large	db.r5d.xlarge	32 GiB	4 vCPUs	2731
R6G Extra Large	db.r6g.xlarge	32 GiB	4 vCPUs	2731
R6GD Extra Large	db.r6gd.xlarge	32 GiB	4 vCPUs	2731
R6I Extra Large	db.r6i.xlarge	32 GiB	4 vCPUs	2731
Z1D Extra Large	db.z1d.xlarge	32 GiB	4 vCPUs	2731
M4 General Purpose Double Extra Large	db.m4.2xlarge	32 GiB	8 vCPUs	2731
M5 Double Extra Large	db.m5.2xlarge	32 GiB	8 vCPUs	2731
M5D Double Extra Large	db.m5d.2xlarge	32 GiB	8 vCPUs	2731
M6G Double Extra Large	db.m6g.2xlarge	32 GiB	8 vCPUs	2731
M6GD Double Extra Large	db.m6gd.2xlarge	32 GiB	8 vCPUs	2731
M6I Double Extra Large	db.m6i.2xlarge	32 GiB	8 vCPUs	2731
T2 General Purpose Double Extra Large	db.t2.2xlarge	32 GiB	8 vCPUs	2731
T3 Double Extra Large	db.t3.2xlarge	32 GiB	8 vCPUs	2731
T4G Double Extra Large	db.t4g.2xlarge	32 GiB	8 vCPUs	2731
M2 High Memory Double Extra Large	db.m2.2xlarge	34.2 GiB	4 vCPUs	2918
R3 Memory Optimized Double Extra Large	db.r3.2xlarge	61 GiB	8 vCPUs	5205
R4 Memory Optimized Double Extra Large	db.r4.2xlarge	61 GiB	8 vCPUs	5205
R5 Extra Large	db.r5.xlarge.tpc2.mem2x	64 GiB	4 vCPUs	5461
R5B Extra Large	db.r5b.xlarge.tpc2.mem2x	64 GiB	4 vCPUs	5461
X2G Extra Large	db.x2g.xlarge	64 GiB	4 vCPUs	5461
R5 Double Extra Large	db.r5.2xlarge	64 GiB	8 vCPUs	5461
R5B Double Extra Large	db.r5b.2xlarge	64 GiB	8 vCPUs	5461
R5D Double Extra Large	db.r5d.2xlarge	64 GiB	8 vCPUs	5461
R6G Double Extra Large	db.r6g.2xlarge	64 GiB	8 vCPUs	5461
R6GD Double Extra Large	db.r6gd.2xlarge	64 GiB	8 vCPUs	5461
R6I Double Extra Large	db.r6i.2xlarge	64 GiB	8 vCPUs	5461
Z1D Double Extra Large	db.z1d.2xlarge	64 GiB	8 vCPUs	5461
M4 General Purpose Quadruple Extra Large	db.m4.4xlarge	64 GiB	16 vCPUs	5461
M5 Quadruple Extra Large	db.m5.4xlarge	64 GiB	16 vCPUs	5461
M5D Quadruple Extra Large	db.m5d.4xlarge	64 GiB	16 vCPUs	5461
M6G Quadruple Extra Large	db.m6g.4xlarge	64 GiB	16 vCPUs	5461
M6GD Quadruple Extra Large	db.m6gd.4xlarge	64 GiB	16 vCPUs	5461
M6I Quadruple Extra Large	db.m6i.4xlarge	64 GiB	16 vCPUs	5461
M2 High Memory Quadruple Extra Large	db.m2.4xlarge	68.4 GiB	8 vCPUs	5837
Z1D 3xlarge	db.z1d.3xlarge	96 GiB	12 vCPUs	8192
X1E Extra Large	db.x1e.xlarge	122 GiB	4 vCPUs	10411
R3 Memory Optimized Quadruple Extra Large	db.r3.4xlarge	122 GiB	16 vCPUs	10411
R4 Memory Optimized Quadruple Extra Large	db.r4.4xlarge	122 GiB	16 vCPUs	10411
R5 Extra Large	db.r5.xlarge.tpc2.mem4x	128 GiB	4 vCPUs	10923
R5B Extra Large	db.r5b.xlarge.tpc2.mem4x	128 GiB	4 vCPUs	10923
X2IEDN Extra Large	db.x2iedn.xlarge	128 GiB	4 vCPUs	10923
R5 Double Extra Large	db.r5.2xlarge.tpc1.mem2x	128 GiB	8 vCPUs	10923
R5B Double Extra Large	db.r5b.2xlarge.tpc1.mem2x	128 GiB	8 vCPUs	10923
X2G Double Extra Large	db.x2g.2xlarge	128 GiB	8 vCPUs	10923
R5 Quadruple Extra Large	db.r5.4xlarge	128 GiB	16 vCPUs	10923
R5B Quadruple Extra Large	db.r5b.4xlarge	128 GiB	16 vCPUs	10923
R5D Quadruple Extra Large	db.r5d.4xlarge	128 GiB	16 vCPUs	10923
R6G Quadruple Extra Large	db.r6g.4xlarge	128 GiB	16 vCPUs	10923
R6GD Quadruple Extra Large	db.r6gd.4xlarge	128 GiB	16 vCPUs	10923
R6I Quadruple Extra Large	db.r6i.4xlarge	128 GiB	16 vCPUs	10923
M5 Eight Extra Large	db.m5.8xlarge	128 GiB	32 vCPUs	10923
M5D Eight Extra Large	db.m5d.8xlarge	128 GiB	32 vCPUs	10923
M6G Eight Extra Large	db.m6g.8xlarge	128 GiB	32 vCPUs	10923
M6GD Eight Extra Large	db.m6gd.8xlarge	128 GiB	32 vCPUs	10923
M6I Eight Extra Large	db.m6i.8xlarge	128 GiB	32 vCPUs	10923
M4 General Purpose Deca Extra Large	db.m4.10xlarge	160 GiB	40 vCPUs	13653
Z1D 6xlarge	db.z1d.6xlarge	192 GiB	24 vCPUs	16384
M5 12xlarge	db.m5.12xlarge	192 GiB	48 vCPUs	16384
M5D 12xlarge	db.m5d.12xlarge	192 GiB	48 vCPUs	16384
M6G 12xlarge	db.m6g.12xlarge	192 GiB	48 vCPUs	16384
M6GD 12xlarge	db.m6gd.12xlarge	192 GiB	48 vCPUs	16384
M6I 12xlarge	db.m6i.12xlarge	192 GiB	48 vCPUs	16384
X1E Double Extra Large	db.x1e.2xlarge	244 GiB	8 vCPUs	20821
R3 Memory Optimized Eight Extra Large	db.r3.8xlarge	244 GiB	32 vCPUs	20821
R4 Memory Optimized Eight Extra Large	db.r4.8xlarge	244 GiB	32 vCPUs	20821
R5 Double Extra Large	db.r5.2xlarge.tpc2.mem4x	256 GiB	8 vCPUs	21845
R5B Double Extra Large	db.r5b.2xlarge.tpc2.mem4x	256 GiB	8 vCPUs	21845
X2IEDN Double Extra Large	db.x2iedn.2xlarge	256 GiB	8 vCPUs	21845
X2IEZN Double Extra Large	db.x2iezn.2xlarge	256 GiB	8 vCPUs	21845
R5 Quadruple Extra Large	db.r5.4xlarge.tpc2.mem2x	256 GiB	16 vCPUs	21845
R5B Quadruple Extra Large	db.r5b.4xlarge.tpc2.mem2x	256 GiB	16 vCPUs	21845
X2G Quadruple Extra Large	db.x2g.4xlarge	256 GiB	16 vCPUs	21845
R5 Eight Extra Large	db.r5.8xlarge	256 GiB	32 vCPUs	21845
R5B Eight Extra Large	db.r5b.8xlarge	256 GiB	32 vCPUs	21845
R5D Eight Extra Large	db.r5d.8xlarge	256 GiB	32 vCPUs	21845
R6G Eight Extra Large	db.r6g.8xlarge	256 GiB	32 vCPUs	21845
R6GD Eight Extra Large	db.r6gd.8xlarge	256 GiB	32 vCPUs	21845
R6I Eight Extra Large	db.r6i.8xlarge	256 GiB	32 vCPUs	21845
M4 General Purpose 16xlarge	db.m4.16xlarge	256 GiB	64 vCPUs	21845
M5 16xlarge	db.m5.16xlarge	256 GiB	64 vCPUs	21845
M5D 16xlarge	db.m5d.16xlarge	256 GiB	64 vCPUs	21845
M6G 16xlarge	db.m6g.16xlarge	256 GiB	64 vCPUs	21845
M6GD 16xlarge	db.m6gd.16xlarge	256 GiB	64 vCPUs	21845
M6I 16xlarge	db.m6i.16xlarge	256 GiB	64 vCPUs	21845
R5 Quadruple Extra Large	db.r5.4xlarge.tpc2.mem3x	384 GiB	16 vCPUs	32768
R5B Quadruple Extra Large	db.r5b.4xlarge.tpc2.mem3x	384 GiB	16 vCPUs	32768
R5 12xlarge	db.r5.12xlarge	384 GiB	48 vCPUs	32768
R5B 12xlarge	db.r5b.12xlarge	384 GiB	48 vCPUs	32768
R5D 12xlarge	db.r5d.12xlarge	384 GiB	48 vCPUs	32768
R6G 12xlarge	db.r6g.12xlarge	384 GiB	48 vCPUs	32768
R6GD 12xlarge	db.r6gd.12xlarge	384 GiB	48 vCPUs	32768
R6I 12xlarge	db.r6i.12xlarge	384 GiB	48 vCPUs	32768
Z1D 12xlarge	db.z1d.12xlarge	384 GiB	48 vCPUs	32768
M5 24xlarge	db.m5.24xlarge	384 GiB	96 vCPUs	32768
M5D 24xlarge	db.m5d.24xlarge	384 GiB	96 vCPUs	32768
M6I 24xlarge	db.m6i.24xlarge	384 GiB	96 vCPUs	32768
X1E Quadruple Extra Large	db.x1e.4xlarge	488 GiB	16 vCPUs	41643
R4 Memory Optimized 16xlarge	db.r4.16xlarge	488 GiB	64 vCPUs	41643
R5 Double Extra Large	db.r5.2xlarge.tpc2.mem8x	512 GiB	8 vCPUs	43691
R5B Double Extra Large	db.r5b.2xlarge.tpc2.mem8x	512 GiB	8 vCPUs	43691
R5 Quadruple Extra Large	db.r5.4xlarge.tpc2.mem4x	512 GiB	16 vCPUs	43691
R5B Quadruple Extra Large	db.r5b.4xlarge.tpc2.mem4x	512 GiB	16 vCPUs	43691
X2IEDN Quadruple Extra Large	db.x2iedn.4xlarge	512 GiB	16 vCPUs	43691
X2IEZN Quadruple Extra Large	db.x2iezn.4xlarge	512 GiB	16 vCPUs	43691
X2G Eight Extra Large	db.x2g.8xlarge	512 GiB	32 vCPUs	43691
R5 16xlarge	db.r5.16xlarge	512 GiB	64 vCPUs	43691
R5B 16xlarge	db.r5b.16xlarge	512 GiB	64 vCPUs	43691
R5D 16xlarge	db.r5d.16xlarge	512 GiB	64 vCPUs	43691
R6G 16xlarge	db.r6g.16xlarge	512 GiB	64 vCPUs	43691
R6GD 16xlarge	db.r6gd.16xlarge	512 GiB	64 vCPUs	43691
R6I 16xlarge	db.r6i.16xlarge	512 GiB	64 vCPUs	43691
M6I 32xlarge	db.m6i.32xlarge	512 GiB	128 vCPUs	43691
R5 6xlarge	db.r5.6xlarge.tpc2.mem4x	768 GiB	24 vCPUs	65536
R5B 6xlarge	db.r5b.6xlarge.tpc2.mem4x	768 GiB	24 vCPUs	65536
X2IEZN 6xlarge	db.x2iezn.6xlarge	768 GiB	24 vCPUs	65536
R5 Eight Extra Large	db.r5.8xlarge.tpc2.mem3x	768 GiB	32 vCPUs	65536
R5B Eight Extra Large	db.r5b.8xlarge.tpc2.mem3x	768 GiB	32 vCPUs	65536
R5 12xlarge	db.r5.12xlarge.tpc2.mem2x	768 GiB	48 vCPUs	65536
R5B 12xlarge	db.r5b.12xlarge.tpc2.mem2x	768 GiB	48 vCPUs	65536
X2G 12xlarge	db.x2g.12xlarge	768 GiB	48 vCPUs	65536
R5 24xlarge	db.r5.24xlarge	768 GiB	96 vCPUs	65536
R5B 24xlarge	db.r5b.24xlarge	768 GiB	96 vCPUs	65536
R5D 24xlarge	db.r5d.24xlarge	768 GiB	96 vCPUs	65536
R6I 24xlarge	db.r6i.24xlarge	768 GiB	96 vCPUs	65536
X1E Eight Extra Large	db.x1e.8xlarge	976 GiB	32 vCPUs	83286
X1 16xlarge	db.x1.16xlarge	976 GiB	64 vCPUs	83286
X2IEDN Eight Extra Large	db.x2iedn.8xlarge	1024 GiB	32 vCPUs	87382
X2IEZN Eight Extra Large	db.x2iezn.8xlarge	1024 GiB	32 vCPUs	87382
X2G 16xlarge	db.x2g.16xlarge	1024 GiB	64 vCPUs	87382
X2IDN 16xlarge	db.x2idn.16xlarge	1024 GiB	64 vCPUs	87382
R6I 32xlarge	db.r6i.32xlarge	1024 GiB	128 vCPUs	87382
X2IEZN 12xlarge	db.x2iezn.12xlarge	1536 GiB	48 vCPUs	131072
X2IDN 24xlarge	db.x2idn.24xlarge	1536 GiB	96 vCPUs	131072
X1E 16xlarge	db.x1e.16xlarge	1952 GiB	64 vCPUs	166571
X1 32xlarge	db.x1.32xlarge	1952 GiB	128 vCPUs	166571
X2IEDN 16xlarge	db.x2iedn.16xlarge	2048 GiB	64 vCPUs	174763
X2IDN 32xlarge	db.x2idn.32xlarge	2048 GiB	128 vCPUs	174763
X2IEDN 24xlarge	db.x2iedn.24xlarge	3072 GiB	96 vCPUs	262145
X1E 32xlarge	db.x1e.32xlarge	3904 GiB	128 vCPUs	333142
X2IEDN 32xlarge	db.x2iedn.32xlarge	4096 GiB	128 vCPUs	349526

When running a standby server, you must set this parameter to the same or higher value than on the master server. Otherwise, queries will not be allowed on the standby server.

# mysql>show max_connections;

You can only modify parameter values in a custom DB parameter group, which means the DB parameter group which you have created not the one which is provided by AWS. Because you can’t change the parameter values in a default DB parameter group.