Quotas and constraints for Amazon RDS - Amazon Relational Database Service
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Quotas and constraints for Amazon RDS

Following, you can find a description of the resource quotas and naming constraints for Amazon RDS.

Quotas in Amazon RDS

Each Amazon account has quotas, for each Amazon 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 Amazon 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 Amazon 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 Amazon 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 Amazon Region
Read replicas per master

ca-central-1: 15

Each of the other supported Regions: 5

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 Amazon 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
Note

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. In the navigation pane, choose Amazon services. Choose Amazon Relational Database Service (Amazon RDS), choose a quota, and follow the directions to request a quota increase. For more information, see Requesting a quota increase in the Service Quotas User Guide.

For RDS for Oracle and RDS for SQL Server, the read replica limit is 5 per source database for each Region.

Backups managed by Amazon Backup are considered manual DB snapshots, but don't count toward the manual snapshot quota. For information about Amazon Backup, see the Amazon 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 Amazon Web Services Support. Open the Amazon Web Services Support Center page, sign in if necessary, and choose Create case. Choose Service limit increase. Complete and submit the form.

Note

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:

  • Must contain 1–63 alphanumeric characters or hyphens.

  • First character must be a letter.

  • Can't end with a hyphen or contain two consecutive hyphens.

  • Must be unique for all DB instances per Amazon account, per Amazon Region.

Database name

Database name constraints differ for each database engine . For more information, see the available settings when creating each DB instance.

Note

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 /, ', ", @, or a space. The password has the following number of printable ASCII characters depending on the DB engine:

  • MariaDB and MySQL: 8–41

  • Oracle: 8–30

  • SQL Server and PostgreSQL: 8–128

DB parameter group name

These names have these constraints:

  • Must contain 1–255 alphanumeric characters.

  • First character must be a letter.

  • Hyphens are allowed, but the name cannot end with a hyphen or contain two consecutive hyphens.

DB subnet group name

These names have these constraints:

  • Must contain 1–255 characters.

  • Alphanumeric characters, spaces, hyphens, underscores, and periods are allowed.

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.

Note

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)

Note

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.

Note

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: