Quotas and constraints for Amazon RDS
Following, you can find a description of the resource quotas and naming constraints for Amazon RDS.
Topics
Quotas in Amazon RDS
Each AWS account has quotas, for each AWS Region, on the number of Amazon RDS resources that can be created. After a quota for a resource has been reached, additional calls to create that resource fail with an exception.
The following table lists the resources and their quotas per AWS Region.
| Name | Default | Adjustable | Description |
|---|---|---|---|
| Authorizations per DB security group | Each supported Region: 20 | No | Number of security group authorizations per DB security group |
| Custom engine versions | Each supported Region: 40 |
Yes |
The maximum number of custom engine versions allowed in this account in the current Region |
| DB cluster parameter groups | Each supported Region: 50 | No | The maximum number of DB cluster parameter groups |
| DB clusters | Each supported Region: 40 |
Yes |
The maximum number of Aurora clusters allowed in this account in the current Region |
| DB instances | Each supported Region: 40 |
Yes |
The maximum number of DB instances allowed in this account in the current Region |
| DB subnet groups | Each supported Region: 50 |
Yes |
The maximum number of DB subnet groups |
| Data API HTTP request body size | Each supported Region: 4 Megabytes | No | The maximum size allowed for the HTTP request body. |
| Data API maximum concurrent cluster-secret pairs | Each supported Region: 30 | No | The maximum number of unique pairs of Aurora Serverless DB clusters and secrets in concurrent Data API requests for the current account and AWS Region. |
| Data API maximum concurrent requests | Each supported Region: 500 | No | The maximum number of Data API requests to an Aurora Serverless DB cluster that use the same secret and can be processed at the same time. Additional requests are queued and processed as in-process requests complete. |
| Data API maximum result set size | Each supported Region: 1 Megabytes | No | The maximum size of the database result set that can be returned by the Data API. |
| Data API maximum size of JSON response string | Each supported Region: 10 Megabytes | No | The maximum size of the simplified JSON response string returned by the RDS Data API. |
| Data API requests per second | Each supported Region: 1,000 per second | No | The maximum number of requests to the Data API per second allowed in this account in the current AWS Region. |
| Event subscriptions | Each supported Region: 20 |
Yes |
The maximum number of event subscriptions |
| IAM roles per DB cluster | Each supported Region: 5 |
Yes |
The maximum number of IAM roles associated with a DB cluster |
| IAM roles per DB instance | Each supported Region: 5 |
Yes |
The maximum number of IAM roles associated with a DB instance |
| Manual DB cluster snapshots | Each supported Region: 100 |
Yes |
The maximum number of manual DB cluster snapshots |
| Manual DB instance snapshots | Each supported Region: 100 |
Yes |
The maximum number of manual DB instance snapshots |
| Option groups | Each supported Region: 20 |
Yes |
The maximum number of option groups |
| Parameter groups | Each supported Region: 50 |
Yes |
The maximum number of parameter groups |
| Proxies | Each supported Region: 20 |
Yes |
The maximum number of proxies allowed in this account in the current AWS Region |
| Read replicas per master | Each supported Region: 15 |
Yes |
The maximum number of read replicas per master |
| Reserved DB instances | Each supported Region: 40 |
Yes |
The maximum number of reserved DB instances allowed in this account in the current AWS Region |
| Rules per security group | Each supported Region: 20 | No | The maximum number of rules per DB security group |
| Security groups | Each supported Region: 25 |
Yes |
The maximum number of DB security groups |
| Security groups (VPC) | Each supported Region: 5 | No | The maximum number of DB security groups per Amazon VPC |
| Subnets per DB subnet group | Each supported Region: 20 | No | The maximum number of subnets per DB subnet group |
| Tags per resource | Each supported Region: 50 | No | The maximum number of tags per Amazon RDS resource |
| Total storage for all DB instances | Each supported Region: 100,000 Gigabytes |
Yes |
The maximum total storage (in GB) for all DB instances added together |
By default, you can have up to a total of 40 DB instances. RDS DB instances, Aurora DB instances, Amazon Neptune instances, and Amazon DocumentDB instances apply to this quota.
The following limitations apply to the Amazon RDS DB instances:
-
10 for each SQL Server edition (Enterprise, Standard, Web, and Express) under the "license-included" model
-
10 for Oracle under the "license-included" model
-
40 for MySQL, MariaDB, or PostgreSQL
-
40 for Oracle under the "bring-your-own-license" (BYOL) licensing model
If your application requires more DB instances, you can request additional DB instances by opening the Service Quotas console
For RDS for Oracle and RDS for SQL Server, the read replica limit is 5 per source database for each Region.
Backups managed by AWS Backup are considered manual DB snapshots, but don't count toward the manual snapshot quota. For information about AWS Backup, see the AWS Backup Developer Guide.
If you use any RDS API operations and exceed the default quota for the number of calls per second, the Amazon RDS API issues an error like the following one.
ClientError: An error occurred (ThrottlingException) when calling the
API_name operation: Rate exceeded.
Here, reduce the number of calls per second. The quota is meant to cover most use
cases. If higher limits are needed, request a quota increase by contacting AWS Support. Open
the AWS Support Center
This quota can't be changed in the Amazon RDS Service Quotas console.
Naming constraints in Amazon RDS
The following table describes naming constraints in Amazon RDS.
| Resource or item | Constraints |
|---|---|
DB instance identifier |
Identifiers have these naming constraints:
|
|
Database name |
Database name constraints differ for each database engine . For more information, see the available settings when creating each DB instance. This approach doesn't apply to SQL Server. For SQL Server, you create your databases after you create your DB instance. |
|
Master user name |
Master user name constraints differ for each database engine. For more information, see the available settings when creating each DB instance. |
|
Master password |
The password for the database master user can include any
printable ASCII character except
|
DB parameter group name |
These names have these constraints:
|
|
DB subnet group name |
These names have these constraints:
|
Maximum number of database connections
The maximum number of simultaneous database connections varies by the DB engine type and the memory allocation for the DB instance class. The maximum number of connections is generally set in the parameter group associated with the DB instance. The exception is Microsoft SQL Server, where it is set in the server properties for the DB instance in SQL Server Management Studio (SSMS).
DBInstanceClassMemory is in bytes. For details about how this value is
calculated, see Specifying DB parameters. Because of memory reserved for the operating system and RDS management processes,
this memory size is smaller than the value in gibibytes (GiB) shown in Hardware specifications for DB instance classes.
If your applications frequently open and close connections, or keep a large number of long-lived connections open, we recommend that you use Amazon RDS Proxy. RDS Proxy is a fully managed, highly available database proxy that uses connection pooling to share database connections securely and efficiently. To learn more about RDS Proxy, see Using Amazon RDS Proxy.
For Oracle, you set the maximum number of user processes and user and system sessions.
Maximum database connections | ||||
|---|---|---|---|---|
| DB engine | Parameter | Allowed values | Default value | Description |
| MariaDB and MySQL | max_connections |
1–100000 | Default for all MariaDB and MySQL versions except MariaDB version 10.6: {DBInstanceClassMemory/12582880} Default for MariaDB version 10.6: LEAST({DBInstanceClassMemory/25165760},12000) If the default value calculation results in a value greater than 16,000, Amazon RDS sets the limit to 16,000 for MariaDB and MySQL DB instances. |
Number of simultaneous client connections allowed |
| Oracle | processes |
80–20000 | LEAST({DBInstanceClassMemory/9868951}, 20000) | User processes |
sessions |
100–65535 | – | User and system sessions | |
| PostgreSQL | max_connections |
6–8388607 | LEAST({DBInstanceClassMemory/9531392}, 5000) | Maximum number of concurrent connections |
| SQL Server | Maximum number of concurrent connections | 0–32767 | 0 (unlimited) | Maximum number of concurrent connections |
In some instances, the total RAM is 16 GiB, or 17,179,869,184 bytes. In these
instances, the variable DBInstanceClassMemory automatically subtracts the
amounts reserved to the operating system and the RDS processes that manage the instance.
The remainder of the subtraction is then divided by 12,582,880. This results in the
maximum connections number being around 1,300, depending on instance type, instance
size, and DB engine.
Database connections consume memory. Setting one of these parameters too high can cause a low memory condition that might cause a DB instance to be placed in the incompatible-parameters status. For more information, see Diagnosing and resolving incompatible parameters status for a memory limit.
You might see fewer than the maximum number of DB connections. This is to avoid potential out-of-memory issues.
File size limits in Amazon RDS
File size limits apply to certain Amazon RDS DB instances. For more information, see the following engine-specific limits:
