Using Amazon RDS Proxy - Amazon Relational Database Service
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Using Amazon RDS Proxy

By using Amazon RDS Proxy, you can allow your applications to pool and share database connections to improve their ability to scale. RDS Proxy makes applications more resilient to database failures by automatically connecting to a standby DB instance while preserving application connections. By using RDS Proxy, you can also enforce Amazon Identity and Access Management (IAM) authentication for databases, and securely store credentials in Amazon Secrets Manager.

Using RDS Proxy, you can handle unpredictable surges in database traffic. Otherwise, these surges might cause issues due to oversubscribing connections or new connections being created at a fast rate. RDS Proxy establishes a database connection pool and reuses connections in this pool. This approach avoids the memory and CPU overhead of opening a new database connection each time. To protect a database against oversubscription, you can control the number of database connections that are created.

RDS Proxy queues or throttles application connections that can't be served immediately from the connection pool. Although latencies might increase, your application can continue to scale without abruptly failing or overwhelming the database. If connection requests exceed the limits you specify, RDS Proxy rejects application connections (that is, it sheds load). At the same time, it maintains predictable performance for the load that RDS can serve with the available capacity.

You can reduce the overhead to process credentials and establish a secure connection for each new connection. RDS Proxy can handle some of that work on behalf of the database.

RDS Proxy is fully compatible with the engine versions that it supports. You can enable RDS Proxy for most applications with no code changes.

Region and version availability

Feature availability and support varies across specific versions of each database engine, and across Amazon Web Services Regions. For more information on version and Region availability of Amazon RDS with RDS Proxy, see Amazon RDS Proxy.

Quotas and limitations for RDS Proxy

The following quotas and limitations apply to RDS Proxy:

  • You can have up to 20 proxies for each Amazon account ID. If your application requires more proxies, you can request additional proxies by opening a ticket with the Amazon Support organization.

  • Each proxy can have up to 200 associated Secrets Manager secrets. Thus, each proxy can connect to with up to 200 different user accounts at any given time.

  • Each proxy has a default endpoint. You can also add up to 20 proxy endpoints for each proxy. You can create, view, modify, and delete these endpoints.

  • For RDS DB instances in replication configurations, you can associate a proxy only with the writer DB instance, not a read replica.

  • Your RDS Proxy must be in the same virtual private cloud (VPC) as the database. The proxy can't be publicly accessible, although the database can be. For example, if you're prototyping your database on a local host, you can't connect to your proxy unless you set up the necessary network requirements to allow connection to the proxy. This is because your local host is outside of the proxy’s VPC.

  • You can't use RDS Proxy with a VPC that has its tenancy set to dedicated.

  • If you use RDS Proxy with an RDS DB instance that has IAM authentication enabled, check user authentication. Users who connect through a proxy must authenticate through sign-in credentials. For details about Secrets Manager and IAM support in RDS Proxy, see Setting up database credentials in Amazon Secrets Manager and Setting up Amazon Identity and Access Management (IAM) policies.

  • You can't use RDS Proxy with custom DNS when using SSL hostname validation.

  • Each proxy can be associated with a single target DB instance . However, you can associate multiple proxies with the same DB instance .

  • Any statement with a text size greater than 16 KB causes the proxy to pin the session to the current connection.

  • Certain Regions have Availability-Zone (AZ) restrictions to consider while creating your proxy. US East (N. Virginia) Region does not support RDS Proxy in the use1-az3 Availability Zone. US West (N. California) Region does not support RDS Proxy in the usw1-az2 Availability Zone. When selecting subnets while creating your proxy, make sure that you don't select subnets in the Availability Zones mentioned above.

  • Currently, RDS Proxy does't support any global condition context keys.

    For more information about global condition context keys, see Amazon global condition context keys in the IAM User Guide.

For additional limitations for each DB engine, see the following sections:

Additional limitations for RDS for MariaDB

The following additional limitations apply to RDS Proxy with RDS for MariaDB databases:

  • Currently, all proxies listen on port 3306 for MariaDB. The proxies still connect to your database using the port that you specified in the database settings.

  • You can't use RDS Proxy with self-managed MariaDB databases in Amazon EC2 instances.

  • You can't use RDS Proxy with an RDS for MariaDB DB instance that has the read_only parameter in its DB parameter group set to 1.

  • RDS Proxy doesn't support MariaDB compressed mode. For example, it doesn't support the compression used by the --compress or -C options of the mysql command.

  • Some SQL statements and functions can change the connection state without causing pinning. For the most current pinning behavior, see Avoiding pinning.

  • RDS Proxy doesn't support the MariaDB auth_ed25519 plugin.

  • RDS Proxy doesn't support Transport Layer Security (TLS) version 1.3 for MariaDB databases.

  • Database connections processing a GET DIAGNOSTIC command might return inaccurate information when RDS Proxy reuses the same database connection to run another query. This can happen when RDS Proxy multiplexes database connections. For more information, see Overview of RDS Proxy concepts.

Important

For proxies associated with MariaDB databases, don't set the configuration parameter sql_auto_is_null to true or a nonzero value in the initialization query. Doing so might cause incorrect application behavior.

Additional limitations for RDS for Microsoft SQL Server

The following additional limitations apply to RDS Proxy with RDS for Microsoft SQL Server databases:

  • The number of Secrets Manager secrets that you need to create for a proxy depends on the collation that your DB instance uses. For example, suppose that your DB instance uses case-sensitive collation. If your application accepts both "Admin" and "admin," then your proxy needs two separate secrets. For more information about collation in SQL Server, see the Microsoft SQL Server documentation.

  • RDS Proxy doesn't support connections that use Active Directory.

  • You can't use IAM authentication with clients that don't support token properties. For more information, see Considerations for connecting to a proxy with Microsoft SQL Server.

  • The results of @@IDENTITY, @@ROWCOUNT, and SCOPE_IDENTITY aren't always accurate. As a work-around, retrieve their values in the same session statement to ensure that they return the correct information.

  • If the connection uses multiple active result sets (MARS), RDS Proxy doesn't run the initialization queries. For information about MARS, see the Microsoft SQL Server documentation.

  • Currently, RDS Proxy does not support RDS for SQL Server DB instances that run on major version SQL Server 2022.

  • RDS Proxy does not support RDS for SQL Server DB instances that run on major version SQL Server 2014.

  • RDS Proxy does not support client applications that can't handle multiple response messages in one TLS record.

Additional limitations for RDS for MySQL

The following additional limitations apply to RDS Proxy with RDS for MySQL databases:

  • RDS Proxy doesn't support the MySQL sha256_password and caching_sha2_password authentication plugins. These plugins implement SHA-256 hashing for user account passwords.

  • Currently, all proxies listen on port 3306 for MySQL. The proxies still connect to your database using the port that you specified in the database settings.

  • You can't use RDS Proxy with self-managed MySQL databases in EC2 instances.

  • You can't use RDS Proxy with an RDS for MySQL DB instance that has the read_only parameter in its DB parameter group set to 1.

  • RDS Proxy doesn't support MySQL compressed mode. For example, it doesn't support the compression used by the --compress or -C options of the mysql command.

  • Database connections processing a GET DIAGNOSTIC command might return inaccurate information when RDS Proxy reuses the same database connection to run another query. This can happen when RDS Proxy multiplexes database connections.

  • Some SQL statements and functions such as SET LOCAL can change the connection state without causing pinning. For the most current pinning behavior, see Avoiding pinning.

  • Using the ROW_COUNT() function in a multi-statement query is not supported.

Important

For proxies associated with MySQL databases, don't set the configuration parameter sql_auto_is_null to true or a nonzero value in the initialization query. Doing so might cause incorrect application behavior.

Additional limitations for RDS for PostgreSQL

The following additional limitations apply to RDS Proxy with RDS for PostgreSQL databases:

  • RDS Proxy doesn't support session pinning filters for PostgreSQL.

  • Currently, all proxies listen on port 5432 for PostgreSQL.

  • For PostgreSQL, RDS Proxy doesn't currently support canceling a query from a client by issuing a CancelRequest. This is the case, for example, when you cancel a long-running query in an interactive psql session by using Ctrl+C.

  • The results of the PostgreSQL function lastval aren't always accurate. As a work-around, use the INSERT statement with the RETURNING clause.

  • RDS Proxy currently doesn't support streaming replication mode.

  • With RDS for PostgreSQL 16, modifications to the scram_iterations value exclusively impact the authentication process between the proxy and the database. Specifically, if you configure ClientPasswordAuthType to scram-sha-256, any customizations made to the scram_iterations value doesn't influence client-to-proxy password authentication. Instead, the iteration value for client-to-proxy password authentication is fixed at 4096.

Important

For existing proxies with PostgreSQL databases, if you modify the database authentication to use SCRAM only, the proxy becomes unavailable for up to 60 seconds. To avoid the issue, do one of the following:

  • Ensure that the database allows both SCRAM and MD5 authentication.

  • To use only SCRAM authentication, create a new proxy, migrate your application traffic to the new proxy, then delete the proxy previously associated with the database.